EDUCATION

Learning Income Tax Return Preparation | Patriot Tax Solutions

2011-01-27T20:09:00.000-08:00

Learning Income Tax Return Preparation | Patriot Tax Solutions

What Are The Responsibilities Of A Tax Preparer? | Patriot Tax Solutions

2011-01-08T00:09:00.000-08:00

What Are The Responsibilities Of A Tax Preparer? | Patriot Tax Solutions

How To Recognize Tax Preparer Fraud | Patriot Tax Solutions

2011-01-07T17:59:00.000-08:00

How To Recognize Tax Preparer Fraud | Patriot Tax Solutions

The Tax Preparer, Revealed | Patriot Tax Solutions

2010-12-23T15:54:00.000-08:00

The Tax Preparer, Revealed | Patriot Tax Solutions

Depreciation Problems engineering economy

2010-03-18T01:12:00.001-07:00

enginnering economy

ME BOARD APRIL 1998

A machine has an initial cost f P50000 and a salvage value of P10000 after 10 years. What is the book value after five years using straight line depreciation?Ans. P30000

ME Board April 1998

An asset is purchased for P500000. The salvage value in 25 years is 100000. What are the the depreciations in the first three years using straight line method?Ans. P48000

CE Board Nov 1997

The cost of equipment is P500000 and the cost of installation is P30000.If the salvage value is 10% of the cost of equipment at the end of 5 years, determine the book value at the end of the fourth year.use straight line method.Ans. P146000

ECE Board Nov 1999

A machine costs P8000 and an estimated life of 10 years with a salvage value of 500. What is the book value after 8 years using straight line method?Ans. P2000

An engineer bought an equipment for P500000. He spent an additional amount of P30000 for installation and other expenses. The salvage value is 10% of the first cost. If the book value at the end of 5 years will be 291500 using straight line method of depreciation, compute the useful life of the equipment in years? Ans 10 years

ME Board April 1992

A unit of welding machine cost P45000 with an estimated life of 5 years.Its salvage value is P2500 find its depreciation rate of sinking fund method. Assuming that will deposit the money to a bank giving 8.5%. Solve for the depreciation.Ans. 7172.54

EE board April 1980

A equipment cost p10000 with a salvage value of P500 at the end of 10 years. Calculate the annual depreciation by sinking fund method at 40% interest.

CHE Board Oct 1980

A 110000 chemical plant had an estimated life of 6 years and a projected scrap value of P10000. After 3 years made it a total loss . How much money would have to be raised to put up a new plant costing P150000, if a depreciation reserved has been maintained during its 3 years of operation by sinking fund method 6%.104359

ME board Sept 1971

A dump truck was bought for 30000 six years ago. It will have a salvage value of P3000 four years from now. It is sold now for P8000. What is the sunk cost if the depreciation method used is sinking fund method at 6%. 7712

CE Board 1999

The corporation purchased a machine for P1 million. Freight and installation charges amounted to 3% of the purchased price. If the machine shall be depreciated over a period of 8 years with a salvage value of 12% of the first cost. Determine the depreciation charged during the 5^th year using the SYD method.100711

ME Board April 1998

An Asset is purchased for P9000. Its estimated life is 10 years, after which it will be sold for P1000. Find the book value during the third year if SYD depreciation is used.5072

ECE Board 1998

ABC corporation makes its policy that for every new equipment purchased the annual depreciation cost should not exceed 20% of the first cost at anytime without salvage value. Determine the length of service if the depreciation used is the SYD method.9 years

ME board April 1996

An asset is purchased for 120000. Its estimated life is 10 years after which it will be sold for 12000. Find the depreciation for the second year using the SYD method.17673

Infrared Sensors

2010-03-01T22:18:00.000-08:00

Infrared proximity sensorsInfrared proximity sensors work by sending out a beam of IR light, and then computing the distance to any nearby objects from characteristics of the returned (reflected) signal. There are a number of ways to do this, each with its own advantages and disadvantages:
Reflected IR strengthYou could build a simple IR proximity sensor out of essentially just an IR LED and IR photodiode. This simple sensor, though, would be prey to background light (i.e., your IR "receiver" would be responding to naturally present IR as well as reflected IR).
Modulated IR signalA better solution would be to modulate your transmitted IR (i.e., to send out a rapidly-varying IR signal), and then have the receive circuitry only respond to the level of the received, matching, modulated IR signal (i.e., to ignore the DC component of the received signal, and only trigger off the AC component). This method, though, is still at the mercy of the characteristics (in particular, IR reflectance) of the obstacle you're trying to sense.
Steve Bolt has a nice circuit to do this here.
TriangulationThe best way to use IR to sense an obstacle is to sense the angle at which the reflected IR is returned to your sensor. By use of a bit of trigonometry, you can then compute distance, knowing the location of your transmit and receive elements. Needless to say, this isn't a simple sensor to build yourself.
You're probably money ahead by just buying an IR proximity sensor with this logic built in. One I particularly like is the Sharp GP2D15 IR Ranger. It has a built-in detection range of 24 cm (this keeps its cost, and the complexity of your interface circuitry down), is reasonably priced, and is available from Acroname. Acroname also has an interesting article covering the operation and utilization of all the impressive Sharp IR sensors here.
The GP2D15 interface is 3-wire with power, ground and the output voltage (the sensor outputs Vcc when it sees something at 24 cm distance); it requires 4.5 - 5.5 V power for operation, and eats about 50 mA of current as long as it is powered. So its advantages are (1) its simple interface, and (2) easy, reliable sensing of obstacles at a distance. Its disadvantages are (1) its requirement for 5 V power, and (2) its requirement for 50 mA of current regardless of whether anything is being sensed (neither of these recommend this sensor for solar-powered 'bots).
If your BEAMbot's circuitry has provision for a "touch-switch" contact sensor, the GP2D15 can easily be used instead, with the addition of an NPN transistor:
Acoustic proximity sensorsOne oft-used method (at least on larger, pricier 'bots) of avoiding hazards is via sonar ranging. Here, acoustic signals ("ping"s) are sent out, with the time of echo return being a measure of distance to an obstacle. This does, unfortunately, require fairly accurate timing circuitry -- so acoustic sensors really require a processor of some sort to drive them. Also note that acoustic sensing essentially requires the use of commercial sensors, there's no real way to "homebrew" something from scratch.
The most common acoustic proximity sensor is the kind used in polaroid cameras. For details on these, I'll refer you to the Acroname site's "Polaroid Sonar Ranging Primer."
There's now also a "new kid on the block" -- the Devantech SRF04 UltraSonic Ranger. Acroname sells it (see their page on it here), and "Tech Geek" has a review on it here. This guy costs about twice what the Sharp IR sensors cost, but has a much wider range of sensing; it costs far less than the Polaroid acoustic rangers, is easier to interface, and draws less power.

Capacitive proximity sensorsYour 'bot can also sense its distance to objects by detecting changes in capacitance around it. When power is applied to the sensor, an electrostatic field is generated and reacts to changes in capacitance cause by the presence of a target. The main disadvantage to this sensor (often called a capaciflector) is that its usefulness is dependent on properties of the obstacles it is sensing (namely, their dialectric constant). The higher the dielectric constant (say, water), the more sensitive a capacitive sensor is to that target. The sensing distance depends on the dielectric constant of the target and the surface areas of the probe and the target.
I go into more depth on this interesting sensor elsewhere.

Inductive proximity sensorsAnother method for sensing distance to objects is through the use of induced magnetic fields. The primary problem with this method is that it is largely confined to sensing metallic objects.

Based on a simple basic Idea, this proximity sensor, is easy to build, easy to calibrate and still, it provides a detection range of 35 cm (range can change depending on the ambient light intensity).This sensor can be used for most indoor applications where no important ambient light is present. For simplicity, this sensor doesn't provide ambient light immunity, but a more complicated, ambient light ignoring sensor should be discussed in a coming article. However, this sensor can be used to measure the speed of object moving at a very high speed, like in industry or in tachometers. In such applications, ambient light ignoring sensor, which rely on sending 40 Khz pulsed signals cannot be used because there are time gaps between the pulses where the sensor is 'blind'...
The solution proposed doesn't contain any special components, like photo-diodes, photo-transistors, or IR receiver ICs, only a couple if IR leds, an Op amp, a transistor and a couple of resistors. In need, as the title says, a standard IR led is used for the purpose of detection. Due to that fact, the circuit is extremely simple, and any novice electronics hobbyist can easily understand and build it.
Object Detection using IR light
It is the same principle in ALL Infra-Red proximity sensors. The basic idea is to send infra red light through IR-LEDs, which is then reflected by any object in front of the sensor.
Then all you have to do is to pick-up the reflected IR light. For detecting the reflected IR light, we are going to use a very original technique: we are going to use another IR-LED, to detect the IR light that was emitted from another led of the exact same type!This is an electrical property of Light Emitting Diodes (LEDs) which is the fact that a led Produce a voltage difference across its leads when it is subjected to light. As if it was a photo-cell, but with much lower output current. In other words, the voltage generated by the leds can't be - in any way - used to generate electrical power from light, It can barely be detected. that's why as you will notice in the
schematic, we are going to use a Op-Amp (operational Amplifier) to accurately detect very small voltage changes.

Block diagram and signal flow graph

2010-02-28T14:04:00.001-08:00

UJT- Unijuction transistor

2009-12-13T08:06:00.000-08:00

UJT Characteristics

The static emitter charÂacteristic (a curve showing the relation between emitter voltage VE and emitter current IE) of a UJT at a given inter base voltage VBB is shown in figure. Â From figure it is noted that for emitter potentials to the left of peak point, emitter current IE never exceeds IEo . The current IEo corresponds very closely to the reverse leakage current ICo of the conventional BJT. This region, as shown in the figure, is called the cut-off region. Once conÂduction is established at VE = VP the emitter poÂtential VE starts decreasing with the increase in emitter current IE. This Corresponds exactly with the decrease in resistance RB for increasing curÂrent IE. This device, therefore, has a negative resistance region which is stable enough to be used with a great deal of reliability in the areas of applications listed earlier. Eventually, the valley point reaches, and any further increase in emitter current IE places the device in the saturation region, as shown in the figure. Three other important parameters for the UJT are IP, VV and IV and are defined below:
Peak-Point Emitter Current. Ip. It is the emitter current at the peak point. It repreÂsents the rnimrnum current that is required to trigger the device (UJT). It is inversely proportional to the interbase voltage VBB.
Valley Point Voltage VV The valley point voltage is the emitter voltage at the valley point. The valley voltage increases with the increase in interbase voltage VBB.
Valley Point Current IV The valley point current is the emitter current at the valley point. It increases with the increase in inter-base voltage VBB.
Special Features of UJT. The special features of a UJT are :
1. A stable triggering voltage (VP)â€” a fixed fraction of applied inter base voltage VBB.
2. A very low value of triggering current.
3. A high pulse current capability.
4. A negative resistance characteristic.
5. Low cost.

Types of graphs

2009-11-30T06:30:00.000-08:00

A chart is a visual representation of data, in which the data are represented by symbols such as bars in a bar chart or lines in a line chart.[1] A chart can represent tabular numeric data, functions or some kinds of qualitative structures.
Four of the most common charts are:
A histogram typically shows the quantity of points that fall within various numeric ranges (or bins).
A bar chart uses bars to show frequencies or values for different categories.

A pie chart shows percentage values as a slice of a pie.

A line chart is a two-dimensional scatterplot of ordered observations where the observations are connected following their order.

A pie chart (or a circle graph) is a circular chart divided into sectors, illustrating relative magnitudes or frequencies. In a pie chart, the arc length of each sector (and consequently its central angle and area), is proportional to the quantity it represents. Together, the sectors create a full disk. It is named for its resemblance to a pie which has been sliced.

The pie chart is perhaps the most ubiquitous statistical chart in the business world and the mass media.[1] However, it has been criticized,[2] and some recommend avoiding it[3][4], pointing out in particular that it is difficult to compare different sections of a given pie chart, or to compare data across different pie charts. Pie charts can be an effective way of displaying information in some cases, in particular if the intent is to compare the size of a slice with the whole pie, rather than comparing the slices among them.[5] Pie charts work particularly well when the slices represent 25 to 50% of the data,[6] but in general, other plots such as the bar chart or the dot plot, or non-graphical methods such as tables, may be more adapted for representing certain information.
Statisticians tend to regard pie charts as a poor method of displaying information. While pie charts are common in business and journalism, they are uncommon in scientific literature. One reason for this is that it is more difficult for comparisons to be made between the size of items in a chart when area is used instead of length

In statistics, a histogram is a graphical display of tabulated frequencies, shown as bars. It shows what proportion of cases fall into each of several categories: it is a form of data binning. The categories are usually specified as non-overlapping intervals of some variable. The categories (bars) must be adjacent. The intervals (or bands, or bins) are generally of the same size.[1]
Histograms are used to plot density of data, and often for density estimation: estimating the probability density function of the underlying variable. The total area of a histogram used for probability density is always normalized to 1. If the length of the intervals on the x-axis are all 1, then a histogram is identical to a relative frequency plot. bar chart or bar graph is a chart with rectangular bars with lengths proportional to the values that they represent. Bar charts are used for comparing two or more values that were taken over time or on different conditions, usually on small data sets. The bars can be horizontally lines or it can also be used to mass a point of view. A bar graph shows you the frequency of each element in a set of data. The height of each bar represents how many of that data element there are. Here's an example. Suppose we bought a small box of Smarties and counted how many of each colour was in the box. We might get results as shown in the table below left. We could then record the frequency of each colour in a bar graph, as shown below right.

You'll notice that we drew this graph with the bars separated by spaces. We didn't have to do this ... we could have had the bars touching, and this still would have been a bar graph.Here's another example of a bar graph, counting numerical values instead of colours. Suppose we surveyed ten elementary students and asked them to tell us their weekly allowance. We might get data like in the table at the right. Below we've organized the data into a frequency table, and then displayed it in a bar graph.
This time we made the bars touch. We still have a bar graph. Bar graphs are used to represent the frequency of discrete items. They can be things, like colours, for which there is no particular order. Or they can be numbers, like allowance amounts, where they can be put into order if you choose to.But (this is the important part) the items are not grouped, and they are not continuous. We'll show you what we meant by that last sentence, in the example below, where we show you a set of data that we will group, and display in a continuous manner on a histogram. Suppose we were surveying the masses of fish in a lake, and we caught and weighed twenty-nine fish. We recorded their masses (in kilograms). Below is the data we might have collected.

If you examine the data above closely, you'll see that there are a lot of mostly different numbers. It wouldn't make much sense to make a bar graph showing the frequency of each individual mass, since most of the bars would just be one ot two units high, and there would be a lot of bars. Instead we're going to group the data.Grouping means to count how many masses there are in different weight categories, or classes. For example, how many fish had a mass between 10 and 12 kilograms? The answer is three. They were 10, 11.4 and 11.8 kg.Note that we don't count 12 in this class of fish. 'Between 10 & 12 kilograms' means 'everything from 10 up to 12, but don't count 12' Below is our grouped frequency table. We've shown (on the left) which masses went into the count for each class. We also indicated the upper bound of each class in red, to remind you that this value isn't counted in that class.

BIKE CELLPHONE CHARGER

2009-11-16T07:08:00.001-08:00

Types of Statistics

2009-11-16T06:52:00.001-08:00

Definition

Statistics – a field of mathematics that provides us with the techniques that enable us to classify, summarize and draw valid inferences according to basic rules of evidence

Types of Statistics

A. Descriptive – is used to say something about a set of information that has been collected only.

the goal of descriptive statistics is to organize and to summarize data so that they are more readily understood

B. Inferential –

Inferential statistics is used to make predictions or comparisons about a larger group (a population) using information gathered about a small part of that population. Thus, inferential statistics involves generalizing beyond the data, something that descriptive statistics oes not do.

the goal of inferential statistics is to take into account the chance factors associated with sampling and subsequently draw valid conclusions

Other distinctions are sometimes made between data types.

• Discrete data are whole numbers, and are usually a count of objects. (For instance, one study might count how many pets different families own; it wouldn’t make sense to have half a goldfish, would it?)

• Measured data, in contrast to discrete data, are continuous, and thus may take on any real value. (For example, the amount of time a group of children spent watching TV would be measured data, since they could watch any number of hours, even though their watching habits will probably be some multiple of 30 minutes.)

• Numerical data are numbers.

• Categorical data have labels (i.e. words). (For example, a list of the products bought by different families at a grocery store would be categorical data, since it would go something like {milk, eggs, toilet paper, . . . }.)

III. Terminology

A. Population – the total group of observations about which one wants to draw a conclusion
1. A parameter is a measurable
characteristic of a population

2. Examples:
correlation proportion
mean s t andard deviation

B. Sample – any subset or subgroup of a population
1. Random samples occur when every element of the population has an equal chance of being selected or drawn
2. A statistic is a measurable characteristic of a sample
3. Examples:
r correlation p proportion
X mean S s t andard deviation
C. Variables – the characteristic we wish to
observe; properties by whereby members of a
group differ from one another
D. Ways to categorize variables
1. Quantitative vs. Qualitative
2. Discrete vs. Continuous
3. Dependent versus independent
E. Qualitative or nominal variables differ in kind rather
than amount (e.g., ethnicity, eye color).
F. Example:
Research question: What is the effect of preschool day
care on children?
- Dependent variable : IQ scores
- Independent variable: presence or absence of daycare
Research question: Do people with high IQs dream more?
- Dependent variable: REM (rapid eye movement)
- Independent variable: Level of IQ

Statistical data collection

What are data?

Data may be defined as a representation of facts or concepts or instructions in a formalized manner, suitable for communication, interpretation or processing by manual or electronic means. An element of data is an item, idea, concept or raw fact (Abdelhak et al., 1996).
In health care, these facts describe specific characteristics of individual patients. Whether we collect data on paper or in a computer, the data should be organized in such a way that we can understand and retrieve them when needed (Davis and LaCour, 2002).

Primary data are obtained from the original datasource. That is, documentation in the patient’smedical/health record collected by staff at either ahospital, clinic or aid post. Daily ward census reportscollected in hospitals are also primary data.

Secondary data are data sets derived from primarydata. Secondary data are individual or aggregatehealth care data found in reports that are summarizedfrom the source. At the hospital or health centre level,secondary data include the master patients’ index,
disease and procedure indexes, health care statistics anddisease registries. At primary care level, they alsoinclude such aspects as the patients’ name index andstatistics.

TERMS in Industrial Electronics

2009-11-16T06:12:00.001-08:00

TERMS In INDUSTRIAL ELECTRONICS

SCR -Silicon Controlled Rectifier

· The term 'silicon-controlled rectifier' is a trade name used by General Electric in 1957 to refer to this type of thyristor.

· Examples of applications for SCR's include:

1) power switching;

2) phase control;

3) battery charging;

4) power inverters;

5) motor switching and control;

6) high-voltage DC conversion

· This extra terminal is called the gate, and it is used to trigger the device into conduction (latch it) by the application of a small voltage.

· To trigger, or fire, an SCR, voltage must be applied between the gate and cathode, positive to the gate and negative to the cathode.

When testing an SCR, a momentary connection between the gate and anode is sufficient in polarity, intensity, and duration to trigger it.

· SCRs may be fired by intentional triggering of the gate terminal, excessive voltage (breakdown) between anode and cathode, or excessive rate of voltage rise between anode and cathode.

SCRs may be turned off by anode current falling below the holding current value (low-current dropout), or by "reverse-firing" the gate (applying a negative voltage to the gate).

Reverse-firing is only sometimes effective, and always involves high gate current.

· SCR terminals may be identified by a continuity meter: the only two terminals showing any continuity between them at all should be the gate and cathode. Gate and cathode terminals connect to a PN junction inside the SCR, so a continuity meter should obtain a diode-like reading between these two terminals with the red (+) lead on the gate and the black (-) lead on the cathode. Beware, though, that some large SCRs have an internal resistor connected between gate and cathode, which will affect any continuity readings taken by a meter. · SCRs are true rectifiers: they only allow current through them in one direction. This means they cannot be used alone for full-wave AC power control. · If the diodes in a rectifier circuit are replaced by SCRs, you have the makings of a controlled rectifier circuit, whereby DC power to a load may be time-proportioned by triggering the SCRs at different points along the AC power waveform.

SCS-Silicon Contrlled Switch

· A silicon-controlled switch, or SCS, is essentially an SCR with an extra gate terminal. · Typically, the load current through an SCS is carried by the anode gate and cathode terminals, with the cathode gate and anode terminals sufficing as control leads. · An SCS is turned on by applying a positive voltage between the cathode gate and cathode terminals. It may be turned off (forced commutation) by applying a negative voltage between the anode and cathode terminals, or simply by shorting those two terminals together. The anode terminal must be kept positive with respect to the cathode in order for the SCS to latch.

GTO-Gate turn OFF Switch

· A variant of the SCR, called a Gate-Turn-Off thyristor (GTO), is specifically designed to be turned off by means of reverse triggering. Even then, reverse triggering requires fairly high current: typically 20% of the anode current.

TRIAC

· A TRIAC acts much like two SCRs connected back-to-back for bidirectional (AC) operation.

· TRIAC controls are more often seen in simple, low-power circuits than complex, high-power circuits. In large power control circuits, multiple SCRs tend to be favored.

· When used to control AC power to a load, TRIACs are often accompanied by DIACs connected in series with their gate terminals. The DIAC helps the TRIAC fire more symmetrically (more consistently from one polarity to another).

· Main terminals 1 and 2 on a TRIAC are not interchangeable.

· To successfully trigger a TRIAC, gate current must come from the main terminal 2 (MT2) side of the circuit!

MCT

· A MOS-gated thyristor uses an N-channel MOSFET to trigger a thyristor, resulting in an extremely low gate current requirement.

· A MOS Controlled Thyristor, or MCT, uses two MOSFETS to exert full control over the thyristor. A positive gate voltage triggers the device; a negative gate voltage forces it to turn off. Zero gate voltage allows the thyristor to remain in whatever state it was previously in (off, or latched on).

UJT- Unijuction Transistor

· A unijunction transistor consists of two bases (B1, B2) attached to a resistive bar of silicon, and an emitter in the center. The E-B1 junction has negative resistance properties; it can switch between high and low resistance.

· The intrinsic standoff ratio is η=R1/(R1+R2) for a PUT; substitute RB1 and RB2, respectively, for a unijunction transistor. The trigger voltage is determined by η.
· Unijunction transistors and programmable unijunction transistors are applied to

1 oscillators
2 timing circuits
3 thyristor triggering

· A PUT (programmable unijunction transistor) is a 3-terminal 4-layer thyristor acting like a unijunction transistor. An external resistor network “programs” η.

· Shockley diodes are four-layer PNPN semiconductor devices. These behave as a pair of interconnected PNP and NPN transistors.
· Like all thyristors, Shockley diodes tend to stay on once turned on (latched), and stay off once turned off.
· To latch a Shockley diode exceed the anode-to-cathode breakover voltage, or exceed the anode-to-cathode critical rate of voltage rise.
· To cause a Shockley diode to stop conducting, reduce the current going through it to a level below its low-current dropout threshold

· Electrical hysteresis, the tendency for a component to remain "on" (conducting) after it begins to conduct and to remain "off" (nonconducting) after it ceases to conduct, helps to explain why lightning bolts exist as momentary surges of current rather than continuous discharges through the air.

· Simple gas-discharge tubes such as neon lamps exhibit electrical hysteresis.
· More advanced gas-discharge tubes have been made with control elements so that their "turn-on" voltage could be adjusted by an external signal. The most common of these tubes was called the thyratron.

· Simple oscillator circuits called relaxation oscillators may be created with nothing more than a resistor-capacitor charging network and a hysteretic device connected across the capacitor.

TERMS

2009-11-16T06:12:00.000-08:00

TERMS In INDUSTRIAL ELECTRONICS

· The term 'silicon-controlled rectifier' is a trade name used by General Electric in 1957 to refer to this type of thyristor.
· Examples of applications for SCR's include: 1) power switching; 2) phase control; 3) battery charging; 4) power inverters; 5) motor switching and control; 6) high-voltage DC conversion
· This extra terminal is called the gate, and it is used to trigger the device into conduction (latch it) by the application of a small voltage.
· To trigger, or fire, an SCR, voltage must be applied between the gate and cathode, positive to the gate and negative to the cathode. When testing an SCR, a momentary connection between the gate and anode is sufficient in polarity, intensity, and duration to trigger it.
· SCRs may be fired by intentional triggering of the gate terminal, excessive voltage (breakdown) between anode and cathode, or excessive rate of voltage rise between anode and cathode. SCRs may be turned off by anode current falling below the holding current value (low-current dropout), or by "reverse-firing" the gate (applying a negative voltage to the gate). Reverse-firing is only sometimes effective, and always involves high gate current.
· A variant of the SCR, called a Gate-Turn-Off thyristor (GTO), is specifically designed to be turned off by means of reverse triggering. Even then, reverse triggering requires fairly high current: typically 20% of the anode current.
· SCR terminals may be identified by a continuity meter: the only two terminals showing any continuity between them at all should be the gate and cathode. Gate and cathode terminals connect to a PN junction inside the SCR, so a continuity meter should obtain a diode-like reading between these two terminals with the red (+) lead on the gate and the black (-) lead on the cathode. Beware, though, that some large SCRs have an internal resistor connected between gate and cathode, which will affect any continuity readings taken by a meter.
· SCRs are true rectifiers: they only allow current through them in one direction. This means they cannot be used alone for full-wave AC power control.
· If the diodes in a rectifier circuit are replaced by SCRs, you have the makings of a controlled rectifier circuit, whereby DC power to a load may be time-proportioned by triggering the SCRs at different points along the AC power waveform.
· A TRIAC acts much like two SCRs connected back-to-back for bidirectional (AC) operation.
· TRIAC controls are more often seen in simple, low-power circuits than complex, high-power circuits. In large power control circuits, multiple SCRs tend to be favored.
· When used to control AC power to a load, TRIACs are often accompanied by DIACs connected in series with their gate terminals. The DIAC helps the TRIAC fire more symmetrically (more consistently from one polarity to another).
· Main terminals 1 and 2 on a TRIAC are not interchangeable.
· To successfully trigger a TRIAC, gate current must come from the main terminal 2 (MT2) side of the circuit!
· A MOS-gated thyristor uses an N-channel MOSFET to trigger a thyristor, resulting in an extremely low gate current requirement.
· A MOS Controlled Thyristor, or MCT, uses two MOSFETS to exert full control over the thyristor. A positive gate voltage triggers the device; a negative gate voltage forces it to turn off. Zero gate voltage allows the thyristor to remain in whatever state it was previously in (off, or latched on).
· A silicon-controlled switch, or SCS, is essentially an SCR with an extra gate terminal.
· Typically, the load current through an SCS is carried by the anode gate and cathode terminals, with the cathode gate and anode terminals sufficing as control leads.
· An SCS is turned on by applying a positive voltage between the cathode gate and cathode terminals. It may be turned off (forced commutation) by applying a negative voltage between the anode and cathode terminals, or simply by shorting those two terminals together. The anode terminal must be kept positive with respect to the cathode in order for the SCS to latch.
· A unijunction transistor consists of two bases (B1, B2) attached to a resistive bar of silicon, and an emitter in the center. The E-B1 junction has negative resistance properties; it can switch between high and low resistance.
· A PUT (programmable unijunction transistor) is a 3-terminal 4-layer thyristor acting like a unijunction transistor. An external resistor network “programs” η.
· The intrinsic standoff ratio is η=R1/(R1+R2) for a PUT; substitute RB1 and RB2, respectively, for a unijunction transistor. The trigger voltage is determined by η.
· Unijunction transistors and programmable unijunction transistors are applied to oscillators, timing circuits, and thyristor triggering.
· A TRIAC acts much like two SCRs connected back-to-back for bidirectional (AC) operation.
· TRIAC controls are more often seen in simple, low-power circuits than complex, high-power circuits. In large power control circuits, multiple SCRs tend to be favored.
· When used to control AC power to a load, TRIACs are often accompanied by DIACs connected in series with their gate terminals. The DIAC helps the TRIAC fire more symmetrically (more consistently from one polarity to another).
· Main terminals 1 and 2 on a TRIAC are not interchangeable.
· To successfully trigger a TRIAC, gate current must come from the main terminal 2 (MT2) side of the circuit!
· A Silicon-Controlled Rectifier, or SCR, is essentially a Shockley diode with an extra terminal added. This extra terminal is called the gate, and it is used to trigger the device into conduction (latch it) by the application of a small voltage.
· To trigger, or fire, an SCR, voltage must be applied between the gate and cathode, positive to the gate and negative to the cathode. When testing an SCR, a momentary connection between the gate and anode is sufficient in polarity, intensity, and duration to trigger it.
· SCRs may be fired by intentional triggering of the gate terminal, excessive voltage (breakdown) between anode and cathode, or excessive rate of voltage rise between anode and cathode. SCRs may be turned off by anode current falling below the holding current value (low-current dropout), or by "reverse-firing" the gate (applying a negative voltage to the gate). Reverse-firing is only sometimes effective, and always involves high gate current.
· A variant of the SCR, called a Gate-Turn-Off thyristor (GTO), is specifically designed to be turned off by means of reverse triggering. Even then, reverse triggering requires fairly high current: typically 20% of the anode current.
· SCR terminals may be identified by a continuity meter: the only two terminals showing any continuity between them at all should be the gate and cathode. Gate and cathode terminals connect to a PN junction inside the SCR, so a continuity meter should obtain a diode-like reading between these two terminals with the red (+) lead on the gate and the black (-) lead on the cathode. Beware, though, that some large SCRs have an internal resistor connected between gate and cathode, which will affect any continuity readings taken by a meter.
· SCRs are true rectifiers: they only allow current through them in one direction. This means they cannot be used alone for full-wave AC power control.
· If the diodes in a rectifier circuit are replaced by SCRs, you have the makings of a controlled rectifier circuit, whereby DC power to a load may be time-proportioned by triggering the SCRs at different points along the AC power waveform.
· Shockley diodes are four-layer PNPN semiconductor devices. These behave as a pair of interconnected PNP and NPN transistors.
· Like all thyristors, Shockley diodes tend to stay on once turned on (latched), and stay off once turned off.
· To latch a Shockley diode exceed the anode-to-cathode breakover voltage, or exceed the anode-to-cathode critical rate of voltage rise.
· To cause a Shockley diode to stop conducting, reduce the current going through it to a level below its low-current dropout threshold
· Electrical hysteresis, the tendency for a component to remain "on" (conducting) after it begins to conduct and to remain "off" (nonconducting) after it ceases to conduct, helps to explain why lightning bolts exist as momentary surges of current rather than continuous discharges through the air.
· Simple gas-discharge tubes such as neon lamps exhibit electrical hysteresis.
· More advanced gas-discharge tubes have been made with control elements so that their "turn-on" voltage could be adjusted by an external signal. The most common of these tubes was called the thyratron.
· Simple oscillator circuits called relaxation oscillators may be created with nothing more than a resistor-capacitor charging network and a hysteretic device connected across the capacitor.

Engineering Economy Simple Interest

2009-11-16T05:07:00.000-08:00

The capital originally invested in a transaction is called the principal P. At any time after the investment of the principal , the sum of the principal and the interest due is called the amount F.

Interest- the amount paid for the use of money called the capital for a certain period of time

Simple interest- the interest to be paid which is proportional to the length of time the principal is used.

Principal- the amount of money used on which interest is charge.

Rate of interest – the amount earned by one unit of principal during a unit of time.

Ordinary Interest- an interest based on the exact no. of 1 bankers tears is equal to 12 months

1 month=30 days

1 year=350 days

Exact Interest based on the exact no. of days, 365 days for ordinary year and 366 days for leap year.

I=Prt

F=P+I

F=P+Prt

F=P(1+rt)

I=Interest

P=Principal

I= rate of interest in decimal

N= number of interest periods

F= total amount

Discount- is the difference between the future worth and its present worth.

Rate of discount- the discount on one unit of principal per unit of time

D=F-P
D=1-[1/(1+i)]

D=i/(1+i)

Equivalent rate of interest

D=i/(1+i)

i=d/(1-d) rate of interest

A man borrowed P2000 from a bank and promise to pay the amount for one year. He received only the amount of P1920 after the bank collected an advance interest of P80. What was the rate of discoun and the rate of interest that the bank collected in advance?

Solution:

rate of discount= (80/2000 )100=0.04=4%

rate of interest=(80/1920)100=0.0417=4.17%

If you borrowed money from your classmate with a simple interest of 12%, find the present worth of P50000; which is due at the end of 7 months.

SOLUTION:

F=P+I

F=P+Prt

50000=P+P(0.12)(7/12)

P=46728

A price tag of a T-shirt is P1200 is payable in 60 days but if paid with in 30 days it will have a 3% discount. Find the rate of interest.

SOLUTION:

Discount = 0.03(1200)=36

Amount to be paid on 30 days = 1200 – 36=1164

I=Prt

36=1164r(30/360)

r=37%

A loan shark charges 12% simple interest on a P300 loan. How much will be repaid if the load is paid back in one lump sum after three years?

SOLUTION:

A=P+Prt

A=300+300(0.12)(3)

A=P408

A bank charges 12% simple interest on a P300 loan. How much will be repaid if the load is paid in one lump sum after three years?

Solution:

A=P+Prt

A=300+300(0.12)(3)

A=P408

Assignment/seatwork
P5000 is borrowed for 75 days at 16% per annum simple interest. How much will be due at the end of 75 days?

Ans. 5166

If you borrow money from your friend with simple interest of 12%, find the present worth of P20000, which is due at the end of nine months.

P=18348

A bank loan of P2000 was made at 8% simple interest. How long would it take in years for the amount of the loan and interest to equal P 3280.

Ans: 8 years

Course Outline

2009-11-09T22:22:00.001-08:00

Topics to be covered in the Course:
I. Silicon Controlled Rectifier(SCR)
1. Theory and Operation of SCR
2. SCR Waveforms
3. SCR Gate characteristics
4. Typical Gate charateristics
Quiz No. 1
II. Triacs and Other Thyristors
1. Theory and operations of Triacs
2. Triac Operations
3. Electrical Characteristics of Triacs
4. Triggering methods for triacs
5. Silicon Bilateral Switches
6. Unilateral Breakover Devices
7. Other devices

Quiz No. 2

Prelim Examination
III. circuit Input Transducers
1. Potentiometers
2. LVDT
3. Pressure transducers
4. Thermocouples
5. Thermistors and RTDS
1. Other temperature devices
1. IV. Photocells and photoelectric Devices
2. Optical Fibers
3. Ultrasonic
4. Strain Gages
6. Accelerometers

Quiz No. 3
V. Measuring Devices
5. Tachometers
6. Hall Effect transducers
7. Other flowmeters Quiz No. 4
8. Resolvers
9. Humidity Transducers
Quiz No. 4
Midterm Examination
VII Industrial Weldings
2. Types of Weldings
3. TIG Weldings
4. MIG Weldings
5. Flux Cored Welding
6. Stick Welding
7. Submerged Arc Welding Benefits
8. Resistance Welding
9. Electron Beam Welding
10. Robotic Welding
11. Sequence operation in making a Weld
1. Weld power
Quiz No. 5
VIII.Industrial Robots
1. The Robot concept
2. Mechanical Configurations of Industrial Robots
3. Mechanical grippers
4. Vacuum Holders
5. Pneumatic grippers
Proximity Sensors.

Final Correcting Devices and Amplifiers
2. Solenoid Valves
3. Two Position Electric Motor Driven Valves
4. Proportional- Position Electric Motor driven Valves
5. Electro pneumatic Valves
6. Electro hydraulic Valves
7. Valve flow characteristics
8. Relays and contactors
9. Thyristors
10. Split-Phase Motors
11. AC Servo Motors
12. Solid State AC servo amplifiers
13. DC Servo Motors
6. Amplifiers for DC servo Motors
Quiz No. 6
Final Examination

TOTAL

Terms in Industrial Electronics

2009-11-09T21:49:00.000-08:00

Terms
1. The silicon-controlled rectifier (SCR) is a rectifier whose state is controlled by the magnitude of the gate current. The forward-bias voltage across the device will determine the level of gate current required to “fire” (turn on) the device. The higher the level of biasing voltage, the less is the required gate current.
2. In addition to gate triggering, an SCR can be turned on with zero gate current simply by applying the sufficient voltage across the device. The higher the gate current, however, the less is the required biasing voltage to turn the SCR on.
3. The silicon-controlled switch has both an anode gate and a cathode gate for controlling the state of the device, although the anode gate is now connected to an n-type layer and the cathode gate to a p-type layer. The result is that a negative pulse at the anode gate will turn the device on, whereas a positive pulse will turn it off. The reverse is true for the cathode gate.
4. A gate turn-off switch (GTO) looks similar in construction to the SCR with only one gate connection, but the GTO has the added advantage of being able to turn the device off and on at the gate terminal. However, this added option of being able to turn the device off at the gate results in a much higher gate current to turn the device on.
5. The LASCR is a light-activated SCR whose state can be controlled by light falling on a semiconductor layer of the device or by triggering the gate terminal in a manner described for SCRs. The higher the junction temperature of the device, the less is the required incident light to turn the device on.
6. The Shockley diode has essentially the same characteristics as an SCR with zero gate current. It is turned on by simply increasing the forward-bias voltage across the device beyond the breakover level.
7. The diac is essentially a Shockley diode that can fire in either direction. The application of sufficient voltage of either polarity will turn the device on.
8. The triac is fundamentally a diac with a gate terminal to control the action of the device in either direction.
9. The unijunction transistor is a three-terminal device with a p-n junction formed between an aluminum rod and an n-type silicon slab. Once the emitter firing potential is reached, the emitter voltage will drop with an increase in emitter current, establishing a negative-resistance region excellent for oscillator applications. Once the valley point is reached, the characteristics of the device take on those of a semiconductor diode. The higher the applied voltage across the device, the higher is the emitter firing potential.
10. The phototransistor is a three-terminal device having characteristics very similar to those of a BJT with a base and collector current sensitive to the incident light intensity. The base current that results is essentially linearly related to the applied light with a level almost independent of the voltage across the device until breakdown results.
11. Opto-isolator contain an infrared LED and a photodetector to provide a linkage between systems that does not require a direct connection. The output detector current is less than but linearly related to the applied input LED current. Furthermore, the collector current is essentially independent of the collector-to-emitter voltage.
12. The PUT (programmable unijunction transistor) is, as the name implies, a device with the characteristics of a UJT but with the added capability of being able to control the firing potential. In general, the peak, valley, and minimum operating voltages of PUTs are less than those of UJTs.

13. Shottky Diode
Advantages:
1. Short Reverse Recovery Time
--- High speed rectifier
2. Low Voltage Drop in Forward Bias
--- High speed TTL IC 74S00 (ECL)
--- Low power TTL IC 74LS00 (TTL)
14. Tunnel Diode
Heavily doped, negative resistance
over forward bias range, so nice for
high frequency oscillator

15. Varicap Diode
PN junction cap decreases when
reverse biasing voltage increases
For variable cap to eliminate the
need of moving part 60pF/0v

16. Zener Diode
narrow junction, Zener breakdown, large change of current causes no
change of voltage, voltage regulator
• LED
III-V semiconductor, emitting photon when electron passes junction
17. Insulated Gate Bipolar Transistor (IGBT)
Combine the advantages
of MOSFET and BJT.
Gate structure like MOS
Output structure like BJT
High voltage 300-1700V

18. Diode AC Switch (DIAC)
Characteristic parameters:
1. Breakover voltage
2. Breakback voltage
3. Voltage symmetry
4. Rating current
5. Power dissipation

19. Triode AC Switch (TRIAC)
Advantages:
1. Controllable trigger
2. Four quadrant device
Application:
1. Light dimmer control
2. Motor speed control
Reason:
Trigger pulse can control
Any percentage of half cycle

Course Outline Statistics

2009-11-08T17:13:00.001-08:00

University of San Agustin
Mathematics Department
Gen. Luna St., Iloilo City

Course Outline in Stat 101 - STATISTICS
Prepared by: Engr. Mark Anthony M. Hervias, ECE

Course Code: Biostat

Course Description: This course is designed to meet the introductory statistical needs of students in the health related disciplines. The study includes topics on collection and presentation of the different statistical data used in health administration, frequency, distribution, measures of central tendencies, measures of variability, normal distribution and hypothesis testing.

Course Credit: 3 units lecture

Contact Hours/Sem: 54 lecture hours

Prerequisite: College Algebra

Placement: 3rd Year, 2nd semester

Course Objectives: At the end of the course and given relevant simulated situations/conditions, the student will be able to apply the concepts, theories and principles of biostatistics (from collection and presentation of the different statistical data used in health administration, frequency, distribution, measures of central tendencies, measures of variability, normal distribution and hypothesis testing) in nursing and health related disciplines.

Course Outline:
A. Introduction
1. Definition
2. Branches/Kinds of Statistics
3. Symbols Used

B. Statistical Data Collection
1. Health Care Overview
2. Data Collection
3. Uses of Data

C. Common Statistical Data Used in Health Administration
1. Population Census
2. Percentage of Occupancy
3. Mortality/Morbidity Rates
4. Autopsy Rules
5. Length of Stay/Discharge
6. Miscellaneous Rates
D. Data Presentation
1. Tabular Presentation
a. Table Formats
b. Frequency Distribution Table
c. Graphical Presentation
d. Data Presentation via Computer

E. Measures of Central Tendencies
1. Mean
2. Median
3. Mode
4. Ranks/Quartiles

F. Measures of Variability
1. Range
2. Average deviation
3. Quartile Deviation
4. Variance
5. Standard Deviation

G. Normal Distribution
1. Normal Curve
2. Normal Curve Areas
3. Application of the Normal Curve Areas

H. Hypothesis Testing
1. Definition of Terms
2. Types/Kinds of Test
3. Steps in Testing Hypothesis
4. Common Statistical Tests Used

I. Validity and Reliability Testing

Grading System:

Grade:

Prelim grade=(Project,Library Work,Assignment)10%+Quiz 40%+ Prelim Exam 50%
Midterm grade=(Project,Library Work,Assignment)10%+Quiz 40%+ Midterm Exam 50%
Final grade=(Project,Library Work,Assignment)10%+Quiz 40%+ Final Exam 50%

Final Rating=(PG+M+F)/3

1A

2009-10-05T20:56:00.001-07:00

Mid
Abalon, Jonquil
d
Arcelo, Excel
d
Bolano, Ben Lorenz
86
Bonete, Harold Henry
d
Bugna Jr Edmundo
d
Cantilero,Jzym Dave
84
Castaneda, Jhelden
d
Cenal, Romyr Patrick
84
Chaves, Abel
85
Dorego, Joshua
84
Duyac, Aldrandreb
d
Felix,Kevin
d
Fernandez, Nichol
85
Flamiano,Remon
82
Isturis,Steven Mel
82
Javellana, Joshua Rey
86
Joren,Joseph Jr.
84
Labiscase,Raymund
83
Labra,Roel
d
Latoza, Anthony
86
Laurente,Arvin Christian
d
Liza,jaypie
87
Marquillero,John Paul
d
Moleno,Jeryll
d
Morit,Felee
d
Navares,michael
d
Noveros,Mark Je
d
Palermo,Jumark
2
Pangue,Levi james
2
Plastico,Tee Jay
85
Porras,Jerald
d
Rubin,Ferdinand
82
Sepacio,Ricardo
86
Tayaba,Paul Cyril
d
Tolosa,Jewel
82
Tranco,Ian Gabriel
83
Travina,Mark Edward
83
Vinson,Jurvinsteven
d
Bebing,Angelyn
2
Eraga,Mary Joy
d
Erenea,Chona Lyn
85
Eusebio,Renea Marie
84
Garrido, Jomaila
85
Lasotas, Rachel
87
Magallon,Maybelle
84
Nasol,Darlyn
2
Subarba,Angelie Mae
80
Superio,Golda Mei
83

JFET self Bias

2009-09-22T17:17:00.000-07:00

JFET self Bias

The Self bias Junction Field Effect Transistor eliminates the need for two dc supplies. The controlling gate to source voltage is now determined by the voltage across a resistor Rs introduced in the source.

JFET

2009-09-15T05:37:00.001-07:00

A "field effect transistor" or a "junction field effect transistor", JFET. With the reverse biased input junction, it has a very high input impedance. Having a high input impedance minimizes the interference with or "loading" of the signal source when a measurement is made.

FIXED BIAS CONFIGURATION

Formulas

Ig≈ 0A

Id=Is

-Vgs=-Vgg

Shockley equation

Id=Idss(1-Vgs/Vp)²

V_DS=V_DD-I_DR_D

V_S=0

V_DS=V_D-V_S

V_D=V_DS+V_S

V_D=V_DS

V_S=V_G-V_S

V_G=V_GS+V_S=V_GS

V_G=V_GS

problem:

Determine the following for the network:

problem:

Determine the following for the network:

For answer email me at hervias.mark@gmail.com

Series Voltage Regulator Problem 2

2009-09-08T07:42:00.001-07:00

Problem 2: Calculate the output voltage and zener current in the regulator circuit for
RL= 2kΩ.

Series Voltage Regulator

2009-09-08T07:39:00.000-07:00

Problem 1: Calculate the output voltage and zener current in the regulator circuit for RL= 1kΩ. Determine Vo,VCE,IR,IL,IB and IZ.

Vo=VZ-VBE=12-0.7=11.3V

VCE=Vi-Vo=20V-11.3V=8.7V

IR=(20V-12V)/220=36.4mA

For RL= 1kΩ

IL=Vo/ RL =11.3V/1kΩ=11.3mA

IB=IC/ß=11.3mA/50=226uA

IZ= IR - IB =36.4mA-226uA=36mA

NEXT

Series Regulator

2009-09-08T07:35:00.000-07:00

Voltage Regulator

Series Regulator Circuit- Transistor Q1 is the series control element and zener diode Dz provides the reference voltage.

Positive Voltage Regulator Design

2009-09-01T17:41:00.000-07:00

motor
generator
power supply

IC Voltage regulators

2009-09-01T17:23:00.000-07:00

IC Voltage regulators

Voltage regulators comprise a class of widely used ICs.Rgulator IC units contain circuitry for reference Source, Comparator amplifier, control device and overload protection all in a single IC.

A power supply can be built using a transformer connected to a ac supply line to step the ac voltage to a desired amplitude, then rectifying that ac voltage , filtering with a capacitor and rc filter , and finally regulating the dc voltage using the IC regulator.

Three Terminal Voltage Regulators.

The fixed voltage regulators has an unregulated dc input voltage, Vi, applied to one input terminal, a regulated output voltage ,Vo from a second terminal with the third terminal connected to ground.

Fixed Positive voltage regulators

The series 78 regulators provide fixed regulated voltages from 5 to 24 V. A 7812 is connected to provide voltage regulation with output from this unit of +12V dc.

Efficiency, Rating and application of Dynamos

2009-09-01T06:16:00.000-07:00

Efficiency, Rating and application of Dynamos

1) A 50 KW gnerator has a efficiency of 91 percent at full load.Calculate the input in kilowatts and the power loss.

Given:
Pl=150 Watts
Efficiency=91% at full load

Required:

Calculate the input Power in Kilowatts and Power loss.

Solution:

Efficiency=(Power out/Power In) 100%

Pin=164.835KW

2) A 15HP motor operates at an efficiency of 87.5 % at full load. If the stray Power loss is approximately one forth of the total loss, calculate the copperloss.

Power Input=[(15 hp)(746)]/0.875
Power Input=12789 Watts

Power Total=Power Input-Power out

Power Total=12789-11190 Watts

stray Power loss = (1/4) Power Total

stray Power loss =(1/4) 1599

stray Power loss =399.75 watts

Power copper loss=Power Total -stray Power loss =1599-399.75=1200 watts

3. The rotational loss in a generator was found to be 780 watts when the generated emf was 132 volts .Determine the rotational loss for generated voltages 138and 126 Volts.

stray Power loss =EgIa
Ia=780/132=5.9 A

At Eg= 138 Volts

stray Power loss =(138)(5.9) =815.5 watts

At Eg= 126 Volts

stray Power loss =(126)(5.9)=743.4 watts

5. The output torque of a motor is 69.2 lb-ft when it operates at 950 rpm.Calculate the losses in the machine and its efficiency whenthe power input is 10900 Watts.

Horsepower=[(2)(Pi )(RPM) (T)]/33000

Horsepower=[(2)(Pi )(950) (69.2)]/33000=12.5HP

Power Input=[(12.5 hp)(746)]=9325 Watts

Power losses=Power Input-Power out =10990-9325=1575 Watts

Efficiency=(Power out/Power In) 100%

Efficiency=(9325/10900) 100% =85.6%

Anne Frank Diary

2009-08-31T21:20:00.001-07:00

The diary is a glaring realistic account of the down side of Nazi Germany and the social crimes committed thereby. The diary is one of the very few attempts to put a personal spin on the Nazi Holocaust and inevitably it ends tragically for the lead character. "Mans inhumanity to man" is a central idea.
The powerful writings of a teenager from the darkness of her hiding place during the Holocaust can teach us much about making a difference for the 21st century here in the Philippines.
We should learn Anne Frank’s Lessons in human rights and dignity.'' Were Crimes ,human rights violations and Injustice are still occurring today here in the Philippines. How do we learn to get along with, respect and care about each other in our communities, as part of a nation, between one country and another?
We study the past in part to become aware of the terrible toll of discrimination, hatred and violence. The lessons of the past and their importance for the future will be always be remembered as not to commit the same mistakes again."To make our democratic society work, each of us must strive to reduce discrimination and prejudice in ourselves and others and educate ourselves as citizens of our community, the Philippines and the world.'

Assignment Power Supply

2009-08-25T17:21:00.000-07:00

Example 1: Determine the regulated voltage and circuit currents for the shunt regulator. Answer:

IC Voltage regulators

2009-08-25T17:17:00.001-07:00

IC Voltage regulators
Voltage regulators comprise a class of widely used ICs.Rgulator IC units contain circuitry for reference Source, Comparator amplifier, control device and overload protection all in a single IC.

A power supply can be built using a transformer connected to a ac supply line to step the ac voltage to a desired amplitude, then rectifying that ac voltage , filtering with a capacitor and rc filter , and finally regulating the dc voltage using the IC regulator.

Three Terminal Voltage Regulators.

The fixed voltage regulators has an unregulated dc input voltage, Vi, applied to one input terminal, a regulated output voltage ,Vo from a second terminal with the third terminal connected to ground.

Fixed Positive voltage regulators

The series &8 regulators provide fixed regulated voltages from 5 to 24 V. A 7812 is connected to provide voltage regulation with output from this uint of +12V dc.

Basic Transistor Shunt Regulator

2009-08-23T21:25:00.001-07:00

Basic Transistor Shunt Regulator

2009-08-23T21:05:00.000-07:00

Determine the regulated voltage and circuit currents for the shunt regulator.

VL=8.2V +0.7=8.9 V

IL=VL/RL=8.9V/100=89 mA

IS=(Vi-VL)/Rs

Is=(22-8.9)/120=109 mA

Ic=Is-IL=109mA-89mA=20mA

Miss Universe 2009

2009-08-23T20:55:00.000-07:00

Miss Universe 2009

Watch it live Miss Universe 2009

NASSAU (AFP) – Young women from 84 countries were set to vie for the Miss Universe crown Sunday, hoping to take the global glamor title now held by Dayana Mendoza.The Venezuelan has just a few more hours left in her reign, with the 58th annual pageant set to get under way at 9:00 pm local time (0100 GMT).On the Miss Universe website, where visitors can participate in an online vote for their favorite, Indonesia's Zivanna Letisha Siregar was in first place, followed by competitors from Brazil, Thailand, Guatemala and Ecuador.But the official decision will be made at the Atlantis Resort by 12-person judging panel that includes Andre Leon Talley, the editor-at-large for American Vogue, actor Dean Cain and supermodel Valeria Mazza.Thursday, contestants rode through the streets of New Providence in a motorcade, watched by Bahamians, residents, tourists and the local and international media."I thought I lived in the best country in the world, but this is pretty... close," Miss Australia Rachael Finch said.Miss Zambia Andella Chileshe Matthews said "I'm definitely enjoying myself. It's my first time (in The Bahamas) but it won't be my last."The main event Sunday will be hosted by Celebrity Apprentice star Claudia Jordan and Access Hollywood co-anchor Billy Bush, and will includes performances by rapper Flo Rida, singers David Guetta and Kelly Rowland and reality star Heidi Montag.For the past two weeks, the women have been touring the various islands and participating in preliminary legs of the competition including the swimsuit presentation in Grand Bahama, a costume presentation, a fashion showcase featuring local designs and fabrics and a state auction dinner in New Providence.Miss Panama, Diana Broce, already won the prize for best national costume.The contestants have also toured other Bahamian islands, including Grand Bahama, Bimini, Exuma, Eleuthera and Abaco, visiting landmarks and posing for photographs.As Hurricane Bill neared earlier this week, several contestants expressed worries about their safety and the prospects for the competition, but the storm's path passed far away from the islands.Live viewing parties have been set up across the Bahamas islands for Bahamians to catch a glimpse of their own contestant, Kiara Sherman, and of the footage of their country, a sprawling Atlantic archipelago.The 12 judges will winnow the pool of competitors, finally announcing their pick, who will be crowned by outgoing Mendoza.The winner will spend a year holding the title, traveling to events and fundraisers and promoting products and charity work.

Basic Transistor Shunt Regulator

2009-08-23T20:34:00.000-07:00

A simple shunt regulator .Resistor Rs drops the unregulated voltage by the amount that depends on the current supplied to the load , Rl.The voltage across the load is set by the zener diode and transistor base emitter voltage. If the load resistance decreases, a reduced drive current to the base of Q1 results, shunting less collector current. The load current is thus larger ,thereby maintaining the regulated voltage across the load. The output voltage is

VL=Vz+VBE

Shunt Voltage regulation

2009-08-23T19:58:00.000-07:00

Shunt Voltage Regulation- A shunt voltage regulator provides regulation by shunting current away from the load to regulate the output voltage. The input unregulated voltage provides the current to the load.Some of the current is pulled away by the control element to maintain the regulated output voltage across the load. If the load voltage tries to change due to a change in the load, the sampling circuit provides the feedback signal to a comparator which provides a control signal to vary the amount of the current shunted away from the load.As the output voltage tries to get larger , for example, the sampling circuit provides a control signal to draw the increased shunt current,providing less load current, thereby keeping the regulated voltage from rising.

NEXT

Energy Conversion

2009-08-23T17:41:00.000-07:00

SEAT PLAN EE 105 –ENERGY CONVERSION

Diala, Kaycee
Seidel, Hirosel
Cabatingan, Celfred
Reyes, Neil Jeffrey
Arriola,Milenses
Navarro,Josua
Tabornal,Jervee
Bartolome,
Jordan So

Acero, Saharah
Tacorda, Maurice
Almendral, Darwin
Mamon, Lemuel
Mamon, Marc

Anjao, Gian Carlo
Genovea , Ken Jorge
Gayam, Angelo
Lariza, Jose Nelson
Fallecido, Edison

ashton kutcher SPREAD

2009-08-16T06:47:00.000-07:00

Nikki isn't a gigolo. He's a sexual grifter, a fun-loving, freeloading hipster who understands his greatest assets are his looks and sexual prowess, which he uses to charm his way into the hearts of the city's richest women and enjoy their lifestyle. Nikki gets a free place to live, fantastic gifts, A-list access, and plenty of sex. The women get to feel young, beautiful... and utterly fulfilled in the bedroom. It's a mutually beneficial set-up. Nikki's latest conquest is Samantha, a stunning middle-aged lawyer who gives him more than he's ever had before. But then he meets a gorgeous waitress his own age named Heather. She comes to visit Nikki at Samantha's house while Samantha is out of town, sees what an incredible place it is... and comes to the mistaken conclusion it's his. Unbeknownst to Nikki, Heather lives by playing the same game. When Samantha comes home, she discovers Nikki's infidelity and he's put out on the street. With nowhere else to turn, Nikki pulls out all the stops to win Heather over and they begin to form their own kind of bond. Sexually charged by a game of one-upsmanship, each shows the other their best grifts, and they unexpectedly begin falling in love - the one thing they can't do in the life they lead. Soon, the truth of their unfolding relationship forces a choice between love and money, and Nikki has to decide whether he can live on his own once and for all in the hopes of finding something real.

Production Status:
Released
Genres:
Comedy
Running Time:
1 hr. 31 min.
Release Date:
August 14th, 2009 (limited)
MPAA Rating:
R for strong sexual content, nudity and language.
Distributors:
Anchor Bay Films
Production Co.:
Katalyst Films, MK2 International
Financiers:
Oceana Media Finance, Barbarian Films, LLC
Filming Locations:
Los Angeles, California USA
Los Angeles, California, USA
Produced in:
United States

Direct Current motor problems

2009-08-16T05:28:00.000-07:00

Problems in Direct Current(DC) Motor Characteristics
A 10 HP 1750 rpm 550 volt shut motor has an armature resistance of 1.55 ohms.If the armature takes 14.8 Amp full load: Calculate a) The counter emf develop by the motor;b) The power develop by the motor in watts and in horsepower.

Given

Pl =10 HP (0.746 watts/HP)

Pl =7.46 KW

Va=550 Volts
S=1750 RPM
RA=1.55 ohm
IA=14.8 A
VBC= 5V

Required:

Calculate the Counter Electromotive force develop by the motor

The power develop by the motor in watts and HP

Solution:

syllabi in power electronics

2009-08-10T22:12:00.000-07:00

COLLEGE OF ENGINEERING AND ARCHITECTURE
UNIVERSITY OF SAN AGUSTIN
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGNINEERING
COURESE SYLLABUS (LECTURE)
Course Code: PELECT2
Course Title :Power Electronics
Credit :3 hours lecture (3 units), 3 hours laboratory(1 unit)
Prerequisite :ECE 102, EE 105
Co-requisite: BASIS OF GRADING:
Cut off Score:
Prelim:
Midterm:
Final:
COURSE DESCRIPTION:
Power Electronics deals with the design and applications of power semiconductors converters, and to analyze converter characteristics in order to understand how these converters interact with the electric utility grid with the various load applications.
Qualification of Lecturer:

GENERAL OBJECTIVES:
At the end of this course, the students should be able to:
1. To familiarized the components and its applications in power electronics
2. To be able to design using power electronics
3. To be able to apply the skills and knowledge they acquired in power electronics. Prepared by:

____________ __________________ __________
Name Signature Date
TEXT:
Recommending Approval:

____________ __________________ __________
Name Signature Date

REFERENCES:
Approved by:

____________ __________________ __________
Name Signature Date
COURSE CONTENT:
PRELIM
Unit I- Industrial devices and linear devices
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• PNPN AND OTHER DEVICES
1. Introduction
2. SCR
3. SCS
4. GTO
5. LASCR
6. Shockley Diode
7. Triac

II. POWER COMPUTATIONS
1. Introduction
2. Power and Energy
3. Inductors and Capacitors
4. Energy Recovery
5. RMS
6. Apparent Power and Power Factor
III. Half wave Rectifier

1. Introduction
2. Resistive Load
3. Resistive-Inductive Load
• To learn the principles of how the Silicon Controlled Rectifier(SCR) triggers, understand the basic operations and determine its characteristics
• To examine the SCR construction, and perform the SCR applications
• To learn the principles of how the TRIAC triggers, understand the basic operations, and determine its characteristics
• To examine the TRIAC construction, and perform the TRIAC applications
• To learn about poer of linear devices such as capacitors and inductors
To distinguish the different kinds load,such as resistive load,inductive load and capacitive load • Lecture / discuss
• Research
• Supplementary articles
• Exam • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam • Electronics Devices & Circuit Theory , 6th Ed. By: R. Boylestad L. Nashelsky
• Gooles. Com
• Industrial Electronics by Maloney

MIDTERM: Rectifiers and Power Supplies
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Half-Wave rectifier with a capacitor
5. Controlled Rectifier

IV. Full wave rectifier

1. Introduction
2. Single Phase Full wave rectifier
3. Controlled Full wave rectifier
V. AC VOLTAGE CONTROLLER: AC TO AC CONVERTER
1. INTRODUCTION
2. SINGLE Phase AC Voltage controller

• Learn the Half wave rectifier and the different formulas
• Learn the Full wave rectifier and the different formulas
•
• To understand voltage multiplier circuits • Lecture / discuss
• Research
• Supplementary articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam • Electronics Devices & Circuit Theory , 6th Ed. By: R. Boylestad L. Nashelsky
• Gooles. Com
• Industrial Electronics by Maloney

FINAL
Unit III- DC converters
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• DC Converter
1. Linear Voltage regulator
2. Basic switching converter
3. Buck Converter
4. Boost Converter

VIII. DC Power Supplies
1. Introduction
2. Transformer Models
3. Flyback converter
4. Forward converter
5. Double Ended Converter
6. Push Pull converter

• To Learn the different types of DC Converter
• Learn Basic switching converters
• To understand The different converters • Lecture / discuss
• Research
• Supplementary articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam • Electronics Devices & Circuit Theory , 6th Ed. By: R. Boylestad L. Nashelsky
• Gooles. Com
• Industrial Electronics by Maloney

syllabi

2009-08-10T21:48:00.001-07:00

COLLEGE OF ENGINEERING AND ARCHITECTURE
UNIVERSITY OF SAN AGUSTIN
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGNINEERING
COURESE SYLLABUS (LECTURE)
Course Code: EE 105
Course Title : Energy Conversion
Credit :
Prerequisite :EE 102, (EE 103)
Co-requisite : BASIS OF GRADING:
Cut off Score:
Prelim:
Midterm:
Final:
COURSE DESCRIPTION:
To learn the different types of motors, generators and transformers. Qualification of Lecturer:

GENERAL OBJECTIVES:
At the end of this course, the students should be able to:
1. To be able to know the principles of motors and generators.
2. To learn the designs of transformers and alternators. Prepared by:

____________ __________________ __________
Name Signature Date
TEXT:
Electrical Machines
By: Siskind, Mc Graw Hill

Electrical Machines
By: Hayt, Mc Graw Hill Recommending Approval:

____________ __________________ __________
Name Signature Date

REFERENCES:
• Electrical Machines
By: Fitzgerald, 1992
• Googles. com Approved by:

____________ __________________ __________
Name Signature Date

COURSE CONTENT
Prelim
Unit I – Direct Current Motor Characteristics & Direct Current Generator Characteristics Estimated Time:
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Rotating Electrical Machines
• Armature Windings
• Field poles
• Types of DC Generators
• Voltage Characteristics of DC motors
• Transformers • To learn the ideas behind shunt motors
• To know the load characteristics of series, shunt and compound motors
• To determine the characteristics of DC generator
• To perform the parallel operations of separately exited generators • Lecture / discussion
• Research
• Supplementary Articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam Electrical Machines
By: Siskind, Mc Graw Hill

Electrical Machines
By: Hayt, Mc Graw Hill

Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims Electrical Machines
• Generator Action
• General Voltage Equation for DC Generator
• Direction of Generated Voltage
• Lorentz Law
• Lenz Law
• Force and Torque Developed by DC Motors
• Cable • Be familiar with Faradays Law
• Know different kinds Direction of Generated Voltage
• To determine what is Lorentz Law
• Lenz Law • Lecture / discuss
• Research
• Supplementary articles • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam By: Siskind, Mc Graw Hill

MIDTERM
Unit II- Transformer
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Types of Armature windings
• Coin span for all types of winding
• Commutator pitch for lap windings
• Define a single phase transformers
• Perform three phase transformer connection
• Know the principles of three phase alternator • Lecture / discuss
• Research
• Supplementary articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam Electrical Machines
By: Siskind, Mc Graw Hill

Electrical Machines
By: Hayt, Mc Graw Hill Siemens Electronic Communications by Kennedy

Unit III- Synchronous Motor
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Types of DC Generators
• No load characteristics of generators
• Degrees of Compounding Adjustment
• • Analyze synchronous motor design
• Examine the three phase squirrel cage induction motor
• Use the design of single phase induction motor • Lecture / discuss
• Research
• Supplementary articles • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam Electrical Machines
By: Siskind, Mc Graw Hill

Electrical Machines
By: Hayt, Mc Graw Hill

Unit V- Alternator
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Alternator Construction
• Frequency of AC generators
• The Revolving Field

• Transformers
• Transformer Action
• Transformer Construction
• Transformer voltage and the general transformer equation
• Voltage and current ratios in transformers
• To learn the ideas behind Alternator
• To know frequency of AC generators
• To determine the revolving field and transformers Lecture / discuss
Research
Supplementary articles Quizzes
Class participation
Class exercises
Recitation
Exam Electrical Machines
By: Siskind, Mc Graw Hill

Electrical Machines
By: Hayt, Mc Graw Hill
• To learn the ideas behind transformers
• To know how transformers are constructed
• To determine the different formulas in transformers • Lecture / discussion
• Research
• Supplementary Articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam
Batteries
• Primary Cells
• Lead Acid batteries
• Specific Gravity
• Hydrometers
• Water for Batteries
• Capacity of a batteries
• Maintaining lead-Acid Cells
• Other chemical Cells • To learn about different batteries
• To know how batteries works

• Lecture / discussion
• Research
• Supplementary Articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam

COLLEGE OF ENGINEERING AND ARCHITECTURE
UNIVERSITY OF SAN AGUSTIN
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGNINEERING
COURESE SYLLABUS (LECTURE)
Course Code: ECE 110
Course Title :Industrial Electronics
Credit :3 hours lecture (3 units), 3 hours laboratory(1 unit)
Prerequisite :ECE 102, EE 105
Co-requisite: BASIS OF GRADING:
Cut off Score:
Prelim:
Midterm:
Final:
COURSE DESCRIPTION:
This course deals with the study of different industrial electronics materials (semiconductors) and its applications such as SCR, TRIAC, FET< three phase rectifier, UJT, single phase inverter and PLC (Programmable Logic Controller). Qualification of Lecturer:

GENERAL OBJECTIVES:
At the end of this course, the students should be able to:
1. To familiarized the components and its applications n industrial electronics
2. To be able to design using industrial electronics
3. To be able to apply the skills and knowledge they acquired in industrial electronics. Prepared by:

____________ __________________ __________
Name Signature Date
TEXT:
Recommending Approval:

____________ __________________ __________
Name Signature Date

REFERENCES:
Approved by:

____________ __________________ __________
Name Signature Date
COURSE CONTENT:
PRELIM
Unit I- Pnpn and other Devices, SCR Characteristics, and TRIAC
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Pnpn and other devices
a. Introduction
b. History of SCR
c. Basic SCR operation
d. SCR symbol and construction
e. SCR two transistor equivalent circuit
• SCR characteristics and ratings
a. Forward breakover voltage
b. Holding Current
c. Forward reverse blocking regions
• Reverse breadown voltage • To learn the principles of how the Silicon Controlled Rectifier(SCR) triggers, understand the basic operations and determine its characteristics
• To examine the SCR construction, and perform the SCR applications
• To learn the principles of how the TRIAC triggers, understand the basic operations, and determine its characteristics
• To examine the TRIAC construction, and perform the TRIAC applications
• To learn the principles of Field Effect Transistor (FET), the small signal model, and the basic FET circuits
To distinguish the different kinds of FETs such as JFET, MOSFET, etc. • Lecture / discuss
• Research
• Supplementary articles
• Exam • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam • Electronics Devices & Circuit Theory , 6th Ed. By: R. Boylestad L. Nashelsky
• Gooles. Com
• Industrial Electronics by Maloney

Lab Work:

1. Silicon Controlled Rectifier
2. TRIAC
3. FET
4. JFET source- follower Circuit

MIDTERM:
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Three Phase inverters
a. The Delta connection
b. Computation of voltage and current of 3 phase
c. Balance Wye Loads
d. Current, Power and voltage per phase computations
e. Computation for AC current and DC current for 3 phase inverters
f. Three anode rectifiers
• Uni-junction Transistor(UJT)
a. Symbol and basic biasing arrangement for the UJT
b. UJT transistor basic construction
c. Typical static emitter- characteristics curves for a UJT.
d. Appearance, specification sheet and terminal identification
e. Computation of UJT problems
• Single Phase inverters
a. Introduction
b. Design circuit
Analysis • Learn the Three-phase inverters
• Learn the Uni-junction Transistor
• To understand how the inverter works

• Lecture / discuss
• Research
• Supplementary articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam • Electronics Devices & Circuit Theory , 6th Ed. By: R. Boylestad L. Nashelsky
• Gooles. Com
• Industrial Electronics by Maloney

Lab work:

5. Three phase inverters
6. UJT (Unijunction Transistor)

FINAL
Unit III- Introductory Experiments on PLC (Programmable Logic Controller)
Topics Specific Objectives Instructional Activities Assessment of Outcomes No. of Hours Value Aims References
• Introductory experiments on Programmable Logic Controllers (PLC) and sensors
a. Introduction to PLC
b. Series and Parallel circuits
c. Numbering systems
d. Boolean Algebra
e. Input and Output
f. Internal Relays
• AND and OR • To learn the experiment on Programmable Logic Controller (PLC) and Sensors • Lecture / discuss
• Research
• Supplementary articles
• Design • Quizzes
• Class participation
• Class exercises
• Recitation
• Exam • Electronics Devices & Circuit Theory , 6th Ed. By: R. Boylestad L. Nashelsky
• Gooles. Com
• Industrial Electronics by Maloney

Lab work:
7. The programmable Logic Controller (PLC)

dc current generator characteristic problems

2009-08-05T04:34:00.001-07:00

DC CURRENT GENERATOR CHARACTERISTICS PROBLEMS

1 A 150 KW 250 VOLT COMPOUND GENERATOR IS CONNECTED LONGSHUNT IF THE SHUNT FIELD RESISTANCE IS 20 OHMS, WHAT IS THE SERIES FIELD CURRENT AT FULL LOAD?

2 IF THE GENERATOR OF PROBLEM 1 IS CONNECTED SHORT SHUNT,WHAT IS THE FULL LOAD SERIES FIELD CURRENT?

3 A LONG SHUNT COMPOUND GENERATOR HAS A SHUNT FIELD WITH 1200 TURNS PER POLE AND A SERIES FIELD WITH 4 ½ TURNS PER POLE.IF THE SHUNT FIELD AND SERIES FIELD AMPERE TURNS ARE, RESPECTIVELY, 1200 AND 196,CALCULATE THE POWER DELIVERED TO A LOAD WHEN THE TERMINAL VOLTAGE IS 230.

4 A SHORT SHUNT COMPOUND GENERATOR HAS A FULL LOAD CURRENT OF 60 AMP. IF THE SERIES FIELD RESISTANCE IS 0.04 OHM AND A DIVERTER CARRIES 24 AMP,WHAT IS THE DIVERTER RESISTANCE?

5 DETERMINE HOW MANY AMPERE TURNS ARE PRODUCED BY EACH SERIES FIELD COIL OF A COMPOUND GENERATOR, GIVEN THE FOLLOWING PARTICULARS:RATING = 100 KW; FULL LOAD VOLTS =600;SERIES FIELD TURNS PER COIL =8.5 ;RESISTANCE OF SERIES FIELD =0.025 OHM;DIVERTER RESISTANCE=0.068 OHM.

6 A 5KW 120 VOLT COMPOUND GENERATOR HAS AN ARMATURE RESISTANCE OF 0.25 OHM, A SERIES FIELD RESISTANCE OF 0.04 OHM, AND A SHUNT FIELD RESISTANCE OF 57.5 OHMS.ASSUMING A LONG SHUNT CONNECTION AND A VOLTAGE DROP AT THE BRUSHES OF 2VOLTS,CALCULATE THE GENERATED EMF AT FULL LOAD.

7 A SHORT SHUNT COMPOUND GENERATOR HAS A SHUNT FIELD RESISTANCE OF 77 OHMS.A SERIES FIELD RESISTANCE OF 0.08 OHM, A COMMUTATING POLE WINDING RESISTANCE OF 0.005 OHM, AND AN ARMATURE RESISTANCE INCLUDING BRUSHES OF 0.02 OHM , WHEN THE ARMATURE CURRENT IS 128 AMP THE GENERATED EMF IS 234.2 VOLTS CALCULATE THE POWER DELIVERED TO THE LOAD.

dc current generator characteristic problems

2009-08-05T04:34:00.000-07:00

2009-07-30T21:16:00.000-07:00

2009-07-30T21:14:00.000-07:00

2009-07-30T21:12:00.000-07:00

2009-07-30T21:10:00.000-07:00

2009-07-30T21:08:00.000-07:00

2009-07-30T21:05:00.000-07:00

2009-07-30T21:03:00.000-07:00

2009-07-30T21:01:00.000-07:00

2009-07-30T20:58:00.000-07:00

2009-07-30T20:14:00.000-07:00

2009-07-30T20:12:00.000-07:00

Bluetooth Seminar

2009-07-30T20:10:00.000-07:00

Percent Regulation

2009-07-30T17:48:00.000-07:00

A convenient standard of reference used to measure the performance of a generator is referring the change in voltage between full load and no load to the full load voltage.

% regulation=[(Vnl-Vfl)/Vfl]X100

COLLEGE OF ENGINEERING UNIVERSITY OF SAN AGUSTIN

2009-07-29T23:39:00.000-07:00

MICHAEL JACKSON ECE STYLE

2009-07-12T00:10:00.001-07:00

MICHAEL JACKSON ECE STYLE

2009-07-12T00:10:00.000-07:00

2009-07-09T05:28:00.000-07:00

2009-07-09T05:24:00.000-07:00

2009-07-09T05:16:00.000-07:00

2009-07-09T05:12:00.000-07:00

2009-07-09T05:09:00.000-07:00

2009-07-09T05:07:00.000-07:00

2009-07-09T05:04:00.000-07:00

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T04:59:00.000-07:00

UNIVERSITY OF SAN AGUSTIN

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T04:54:00.000-07:00

Labra and company-THE ERASER HEADS

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T04:48:00.000-07:00

Ms allen centena and ms tintin

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T04:44:00.000-07:00

university of san agustin engineering faculty and staff

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T04:20:00.000-07:00

THE UNIVERSITY OF SAN AGUSTIN ENGINEERING FACULTY AND STAFF

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T04:17:00.000-07:00

FR NELSON SERDA,ENGR. JOSEPHINE GELLECANAO,ARCHITECT CHAM,GLENDA GUANZON,ENGR, ENGR ROGER WONG

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T04:10:00.000-07:00

FR NELSON SERDA, DEAN REYNALDO ASUNCION,ENGR. JOSEPHINE GELLECANAO,ARCHITECH CHAM, GLENDA GUANZON AND ENGR.

NEXT

2009-07-09T04:00:00.000-07:00

DEAN REYNALDO ASUNCION-UNIVERSITY OF SAN AGUSTIN

NEXT

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T03:54:00.000-07:00

REV. FR. NELSON SERDA-UNIVERSITY OF SAN AGUSTIN

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T03:49:00.000-07:00

UNIVERSITY OF SAN AGUSTIN ENGINEERING FIRST YEAR STUDENTS

MORE PLS...

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T03:44:00.001-07:00

UNIVERSITY OF SAN AGUSTIN COMPUTER ENGINEERING STUDENTS

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T03:35:00.000-07:00

]

UNIVERSITY OF SAN AGUSTIN ENGINEERING STUDENTS

USA-ENGINEERING RECOGNITION PROGRAM

2009-07-09T03:29:00.000-07:00

The University of san agustin Gym is slowly filling up with engineering students

ENGINEERING RECOGNITION PROGRAM

2009-07-09T03:26:00.000-07:00

The University of san agustin gym-The Stage-Engineering Recognition Program

PC Repair: A Reunion with an "Old Friend"

2009-07-05T22:54:00.000-07:00

PC Repair: A Reunion with an "Old Friend"

To study or not?

2009-07-05T22:02:00.001-07:00

Every other day, my son works on a few pages of summer math homework. We also have to keep a reading log, which tracks the seven books he's to read over about 12 weeks. Did I mention he's going into second grade?Here's the thing: My kid loves math (for now) and he lists reading as one of his favorite things to do (for now). Summer homework isn't a battle for us unlike last year, where he spent the last two days of his summer break working on his math workbook and completing a journal. (I'd like to think he learned his lesson about procrastination.)As a parent, I like that he has summer homework because it helps fosters a love of learning. The homework isn't intense; it's really a review of the past year, just to keep the academic juices flowing. The other benefit is that his homework routine doesn't get completely thrown, which makes it easier for all of us when school starts in late August.But I'm sure many of you dread having to ask your kids to do their summer homework––either because they hate doing it or because you feel like homework shouldn't be assigned over the break.According to the National Center for Summer Learning at Johns Hopkins University, most students lose about "two months of grade level equivalency in mathematical computation skills" during their summer vacation. This "summer slide" is one reason why teachers spend so much time at the front end of the school year reviewing what their students learned the previous year.

ENG 1-C 8-11 AM THURS

2009-06-29T22:53:00.000-07:00

AMAGO,JASON
ATAS, RENE LOUIE
BAGUIORO, WILMER
BAQUIRAN,DUKE BELT
BELASA,ROBERT JOHN
BERDEJO,ISRAYL ROLAND
CABALFIN,LOUIE JAMES
CALANAO,RAYMOND DAVID
CAMARINAS, CHRISTOPHER
CHAN,EDDIE
CHIN,MARTIN JOHN
DAGUM,PHILIP
DELAVEGA,ARGEL
DIPUTADO,VAN VINCENT
ELAGO,ISRAEL
ESTOLLOSO,JELEONE
FERMARAN,MARK CHRISTIAN
GELLECANAO,KARL IVAN
JARAVILLA,JOEMAR
LABRADOR,CARL BRIAN
LACANG,BRYAN EMBER
LUMINARIO,ARIEL
MADRONES,JOSE JAMEL
MANILUM,GERALD ANTHONY
MANUEL,JOSE ALRAN TUAZON
MATAGANAS,MHAR
MIRANDA,JOHN ROY
MUYCO,ROY
NAVARRO,PAUL JOHN
NGALONGALAY,ALVIEN
OLIVARES,NORMAN FRANCIS
PADRIGO,JERYL
PONSARAN,ROMAN
PUERTOLLANO,DAN HENRIC
REYES,JERICK PAUL
RICOTE,JAN
SHIMOZURO,JOJE
SIM,KENNY WILLIAMS
ATINADO,JILLIAN
CAMARIG,MARY ROSE JANE
CARBON,NINA PAULINE
CLAUDIO,ANN MARGARETTE
ERQUITA,APRIL ROVE
GALVAN, CLAIRE
ILUSTRISIMO,KATHERINE
PEDROSO,NIITIISHVARII
PELAEZ,MARY JANE

ENG 1-A BATCH 2009-2010

2009-06-29T22:50:00.000-07:00

Abalon, Jonquil
Arcelo, Excel
Bolano, Ben Lorenz
Bonete, Harold Henry
Bugna Jr Edmundo
Cantlilero,Jzym Dave
Castaneda, Jhelden
Cenal, Romyr Patrick
Chaves, Abel
Dorego, Joshua
Duyac, Aldrandreb
Felix,Kevin
Fernandez, Nichol
Flamiano,Remon
Isturis,Steven Mel
Javellana, Joshua Rey
Joren,Joseph Jr.
Labiscase,Raymund
Labra,Roel
Latoza, Anthony
Laurente,Arvin Christian
Liza,jaypie
Marquillero,John Paul
Moleno,Jeryll
Morit,Felee
Navares,michael
Noveros,Mark Je
Palermo,Jumark
Pangue,Levi james
Plastico,Tee Jay
Porras,Jerald
Rubin,Ferdinand
Sepacio,Ricardo
Tayaba,Paul Cyril
Tolosa,Jewel
Tranco,Ian Gabriel
Travina,Mark Edward
Vinson,Jurvinsteven
Bebing,Angelyn
Eraga,Mary Joy
Erenea,Chona Lyn
Eusebio,Renea Marie
Garrido, Jomaila
Lasotas, Rachel
Magallon,Maybelle
Nasol,Darlyn
Subarba,Angelie Mae
Superio,Golda Mei

ENGINEERING 1-B BATCH 2009-2010

2009-06-29T22:48:00.000-07:00

AGUILAR,CLARO
ALQUISOLA,CLINT NORMAN
ANGARAY,MICHAEL
BEQUIN,JEMARK
CACERES,NINO RAMJE
CAJURAO,EFRHAEM
CANATA,RENE
DEASIS,REY GLEN
DIONIO,ROBERT
ERTA,MICHAEL JOHN
GAWAL,EMERSON
GICANO,DANNY
GILONGOS,R JAY
GONZAGA,VERNIE
LABRADOR,LOUIE
LAGUDA,RODNEY
LORCA,RHODE NEAL
MAAMUD,JOB JERSON
MACALALAG,RAY ADRIAN
MAQUILING,ENGLISON
MONTECLARO,JAMME JOE
NAPARAN, Kristian
NATALARAY, JERIMEN RENZ
OBAREDES, FRANCIS
PALETE, DEXTER JOHN
PANISTANTE,LOUIE GENE
PARONDO, ROLLY
PEDICO,CHADWEYN
POLIDO,RENDELL
PROVIDO,JOJO
SATURNINO,JIVAN JEZTYLL
SERIA,HENRY
SUJEDE,OIRECILE
TICAR,JOHN LEE
TINAS,JERIEL
TRABADO,JEAN PAUL
VALEBIA,MARK RYAN
VILLA,CHRISTIAN JAY
BAUTISTA,HYA MAY
DIA,J BEATRIX
LAPASARAN,EUGENIO MARIE
LICONG,CHERRY ANN
MENGUIS,RHECY ANN
NILLO,KRISTINE JOY
PATCHICOY,JAQUILINE
SONGSONG,JACQUELINE

quiz 1

2009-06-27T01:05:00.001-07:00

I will have a short quiz in LECTURE 1 and 2 ,this monday. Pls study the terms.It will be Identification and enumeration.

ELECTRICAL MACHINERY GENERALIZATIONS

2009-06-25T02:14:00.000-07:00

ELECTRICAL MACHINERY GENERALIZATIONS

1. GENERATOR – mechanical energy's is converted into electrical energy.
2. MOTOR- electrical energy is converted to mechanical energy.
3. PRIME MOVER- a mechanical machine that drives the electric generator.
4. AMRATURE WINDING- a laminated steel core containing current carrying copper wires.
5. ROTARY CONVERTER- electrical energy of one form is charged into electrical energy of another.
6. FREQUENCY CONVERTER- its function is to change ac electrical energy at one frequency energy at another frequency.
7. SHUNT GENERATOR / SELF EXCITED SHUNT GENERATOR- if the excitation is produced by a simple winding connected to the positive and negative brushes.
8. SEPARATELY EXCITED SHUNT GENERATORS- excitation is produced by a single winding connected to the positive and negative bus bars fed by another dc generators.
9. COMPOUND GENERATORS- has two complete sets of field windings for excitation purposes.
10. SERIES GENERATORS- a generator that contains series field for control purposes.
11. ALTERNATORS- constructed that armature series and its windings are stationary while the field poles rotate.
12. SHUNT MOTOR- a motor in which the field windings is connected in parallel with the armature.
13. SERIES MOTOR- a field winding that is connected in series with armature.
14. COMPOUND MOTOR- a motor that is excited by a combination of a shunt field connected in shunt with the motor and a series field with the armature.
15. SHADED POLE AND RELUCTANCE MOTOR- are built in very small sizes, they are cheap to construct, have low starting torque, little overload capacity and low efficiency and maybe speed controlled.
16. SPLIT-PHASE MOTOR- are manufactured in sizes up to about ¾hp, they are comparatively low in cost, have fair starting torque, not much overload capacity and fair efficiency and operate at nearly constant speed.
17. CAPACITOR-START SPLIT-PHASE MOTORS- when a split phase motor equipped with capacitors have high starting torque used only during the starting period.
18. TWO-VALVE CAPACITORS- a split phase motor that uses two valves of capacitor for starting and running.
19. UNIVERSAL MOTORS- series motors that are constructed for series on direct or alternating current up to 60 hertz.
20. SYNCHRONOUS MOTORS- operate at synchronous speed determined by the frequency of the supply and the no. of poles on the machine.
21. POLYPHASE MOTORS- machines served with two or three phase powers.
22. SQUIRREL CAGE INDUCTOR MOTOR- polyphase motors which desirable all purpose characteristics.
23. WOUND ROTOR – replaces the squirrel cage motor due to its speed control.
24. SCHRAGE MOTOR – a special motor construction that has wide speed control possibilities.
25. TRANSFORMER – a simple device used primarily for the purpose of changing voltage from one valve to another.
26. AUTO TRANSFORMER – when the electric circuit of transformers are joined together.
27. PRIMARY – the transformer winding that is connected to the supply.
28. SECONDARY – when the winding feeds the load.
29. STEP – UP – transformer that raises the primary voltage to a higher valve.

Motor and Generator Terminologies

2009-06-25T01:58:00.000-07:00

Dynamo Development
The first generators and motors were called dynamos or dynamoelertric machines. Dynamo is from the Greek word dynamis which means power.

Webster defines dynamoelectric as "relating to the conversion of mechanical energy into electrical energy or vice versa". The word motor is from the Latin word motus which means one that imparts motion or prime mover. The dynamo was the result of the efforts of several people, in different countries, in the mid-nineteenth century, to make electricity work for them.

Definitions

Dynamo:
From the Greek word dynamis, which means power
Dynamoelectric:
Relating to the conversion by induction of mechanical energy into electrical energy or vice versa

Dynamoelectric machine:
A dynamo or generator
Motor:
From the Latin word motus, one that imparts motion, prime mover. A device that changes electrical energy into mechanical energy.
Generator:
A device that changes mechanical energy into electrical energy. Although the terms AC and DC generator are in common usage, a generator is normally considered to be a device that provides DC current.
Alternator:
A device that changes mechanical energy into an alternating current electrical energy, an AC generator.

Landmarks Of Electric Motor Development

The core function of electric motors is to convert electrical current into mechanical force. The history of motors can be related to times when fundamentals of electromagnetic induction were introduced. In early 1800, three popular scientists Oersted, Faraday and Gauss came up with the basic principals of electromagnetic induction.
In 1820, Andre Ampere and Hans Oersted made the most fascinating invention. They discovered that electric current produces magnetic field leading to the invention of the basic DC motor some ten years later. No body in particular is acclaimed with the sole invention of the DC motor, as it was a gradual process with involvement of many people
Michael Faraday from England set to prove the theory proposed by Ampere and Oersted. In 1921, he successfully demonstrated in his experiment by converting electrical energy into motion. His motor was made of a free-hanging wire that was plunged into a puddle of mercury. A permanent magnet was placed in the centre of the mercury pool. On passing through the wire, it rotated around the magnet. It proved that the current resulted in a circular magnetic field around the wire. This is the simplest form of electric motor.
Ten years later, it was Joseph Henry who built an improved motor based upon Faraday’s experimental motor. He constructed a device whose rotating part was an electromagnet with a horizontal axis. The motion resulted in two vertical permanent magnets, alternately attracted and repelled at end of the electromagnet. This made the magnet sway back and forth at 75 cycles per minute.
Till this stage, use of electromagnetic field in motors was restricted to lab experiments. A major development took place with William Sturgeon’s invention of commutator. He is credited with the discovery of first rotary electric motor. Sturgeon made use of horseshoe electromagnets to build rotating and stationary magnetic fields. His shunt wound DC motor was the first to produce a continuous rotary motion using all essentials of modern-day DC motors.
Another early electric motor design used a reciprocating plunger inside a switched solenoid; an electromagnetic version of a two-stroke internal combustion engine. A remarkable fact points that the modern day version of motor was actually an accident. In the year 1873, Zénobe Gramme accidentally linked a spinning dynamo to a similar unit, driving it as a motor.
The accident proved to be successful. And the journey of development started from then on. There are many amusing facts and chapters in the development of the present day motor. Motor is the core of many hi-tech electronic, electro-mechanical and electrical gadgets all over the world.
1820 The discovery of electromagnetism Hans Christian Oersted, Danish
1827 The statement of the law of electric conduction, Ohm's law George S. Ohm, German

1830 The discovery of electromagnetic induction Joseph Henry, American
1831 The discovery of electromagnetic induction Michael Faraday, English

The first practical dynamo, about 1867

Types of Motors

Electric motors are practically used everywhere round us. Starting with your kitchen fan, microwave oven, refrigerator, vacuum cleaners, hair dryers to car heaters and radiators, everything uses a motor. Following are the main types of motors.

1. AC Motor
There are two main types of AC motors. The most popular and simple motor is the three-phase AC induction motor. It is also known as the squirrel cage motor. The synchronous motor rotates at exactly the supply frequency or submultiples of the supply frequency. A typical AC motor consists of two parts:
o An exterior stationary stator with coils that uses AC current to produce a revolving magnetic field
o An interior rotor linked to the output shaft that employs torque using the rotating field
2. Stepper Motors

Stepper motor is an electro-mechanical device that converts electrical current into torque output. It popularly finds application as a positioning device for precision control. The motor works by converting electrical impulses into distinct mechanical rotatory motion. Normally this motion of a stepper motor is measured in degrees, or in steps.
3. DC Motor

While an electric motor converts electrical energy into mechanical force, the reverse if true for DC motor. DC motors convert mechanical force into electrical energy with the use of a generator or dynamo. DC motors can be primarily divided into Brushed DC motors and Brushless DC motors

4. Brushed DC motors

The brushed DC motor has an ancient history. In this type of motor, a permanent magnetic field is produced in the stator with the help of permanent magnets or electro-magnetic windings. If the field is created by permanent magnets, the motor is called a permanent magnet DC motor. If it is generated using electromagnetic windings, the motor is named as Shunt wound DC motor.

5. Brushless DC motor

A brushless DC motor is an electric motor with similar operations as the DC motor. The only difference is that the role of rotor and stator are inverted in the brushless DC motor. The motor’s rotor has a set of permanent magnets while the stator here consists of electromagnets. As the name suggests, the motor does not use brushes, but the function of commutator takes place by an electronic circuit. It switches the current to various stator coils as and when required.
6. Linear Motor
A linear motor is essentially an electric motor with an unrolled stator. It results in the Linear motor producing linear force along its length instead of conventional torque as in other motors.
7. Servo motor
Servo is a tiny motor with specific function. This motor can select between vertical or horizontal polarization. Popularly used for motion controls in electronic gadgets and robots and computer hard disc drives, the motor works more like an alternator. It uses special circuit to make them rotate electrically. Some servomotors are used in reverse to generate AC current
8. Universal motors
A variant of the wound field DC motor is the universal motor. The name derives from the fact that it may use AC or DC supply current, although in practice they are nearly always used with AC supplies. The principle is that in a wound field DC motor the current in both the field and the armature (and hence the resultant magnetic fields) will alternate (reverse polarity) at the same time, and hence the mechanical force generated is always in the same direction.
9. Squirrel Cage rotors: Most common AC motors use the squirrel cage rotor, which will be found in virtually all domestic and light industrial alternating current motors. The squirrel cage takes its name from its shape - a ring at either end of the rotor, with bars connecting the rings running the length of the rotor. It is typically cast aluminum or copper poured between the iron laminates of the rotor, and usually only the end rings will be visible. The vast majority of the rotor currents will flow through the bars rather than the higher-resistance and usually varnished laminates. Very low voltages at very high currents are typical in the bars and end rings; high efficiency motors will often use cast copper in order to reduce the resistance in the rotor.
10. Wound Rotor: An alternate design, called the wound rotor, is used when variable speed is required. In this case, the rotor has the same number of poles as the stator and the windings are made of wire, connected to slip rings on the shaft. Carbon brushes connect the slip rings to an external controller such as a variable resistor that allows changing the motor's slip rate. In certain high-power variable speed wound-rotor drives, the slip-frequency energy is captured, rectified and returned to the power supply through an inverter.
11. Three-phase AC synchronous motors
If connections to the rotor coils of a three-phase motor are taken out on Slip-rings and fed a separate field current to create a continuous magnetic field (or if the rotor consists of a permanent magnet), the result is called a synchronous motor because the rotor will rotate in synchronism with the rotating magnetic field produced by the polyphase electrical supply.
The synchronous motor can also be used as an alternator.
12. Two-phase AC servo motors
A typical two-phase AC servo motor has a squirrel-cage rotor and a field consisting of two windings: 1) a constant-voltage (AC) main winding, and 2) a control-voltage (AC) winding in quadrature with the main winding so as to produce a rotating magnetic field. The electrical resistance of the rotor is made high intentionally so that the speed-torque curve is fairly linear. Two-phase servo motors are inherently high-speed, low-torque devices, heavily geared down to drive the load.
13. Single-phase AC induction motors
Three-phase motors inherently produce a rotating magnetic field. However, when only single-phase power is available, the rotating magnetic field must be produced using other means. Several methods are commonly used.
A common single-phase motor is the shaded-pole motor, which is used in devices requiring low torque, such as electric fans or other small household appliances. In this motor, small single-turn copper "shading coils" create the moving magnetic field. Part of each pole is encircled by a copper coil or strap; the induced current in the strap opposes the change of flux through the coil (Lenz's Law), so that the maximum field intensity moves across the pole face on each cycle, thus producing the required rotating magnetic field.
Another common single-phase AC motor is the split-phase induction motor, commonly used in major appliances such as washing machines and clothes dryers. Compared to the shaded pole motor, these motors can generally provide much greater starting torque by using a special startup winding in conjunction with a centrifugal switch.
In the split-phase motor, the startup winding is designed with a higher resistance than the running winding. This creates an LR circuit which slightly shifts the phase of the current in the startup winding. When the motor is starting, the startup winding is connected to the power source via a set of spring-loaded contacts pressed upon by the not-yet-rotating centrifugal switch. The starting winding is wound with fewer turns of smaller wire than the main winding, so it has a lower inductance (L) and higher resistance (R). The lower L/R ratio creates a small phase shift, not more than about 30 degrees, between the flux due to the main winding and the flux of the starting winding. The starting direction of rotation may be reversed simply by exchanging the connections of the startup winding relative to the running winding.
The phase of the magnetic field in this startup winding is shifted from the phase of the mains power, allowing the creation of a moving magnetic field which starts the motor. Once the motor reaches near design operating speed, the centrifugal switch activates, opening the contacts and disconnecting the startup winding from the power source. The motor then operates solely on the running winding. The starting winding must be disconnected since it would increase the losses in the motor.
In a capacitor start motor, a starting capacitor is inserted in series with the startup winding, creating an LC circuit which is capable of a much greater phase shift (and so, a much greater starting torque). The capacitor naturally adds expense to such motors.
Another variation is the Permanent Split-Capacitor (PSC) motor (also known as a capacitor start and run motor). This motor operates similarly to the capacitor-start motor described above, but there is no centrifugal starting switch and the second winding is permanently connected to the power source. PSC motors are frequently used in air handlers, fans, and blowers and other cases where a variable speed is desired. By changing taps on the running winding but keeping the load constant, the motor can be made to run at different speeds. Also provided all 6 winding connections are available separately, a 3 phase motor can be converted to a capacitor start and run motor by commoning two of the windings and connecting the third via a capacitor to act as a start winding.
Repulsion motors are wound-rotor single-phase AC motors that are similar to universal motors. In a repulsion motor, the armature brushes are shorted together rather than connected in series with the field. Several types of repulsion motors have been manufactured, but the repulsion-start induction-run (RS-IR) motor has been used most frequently. The RS-IR motor has a centrifugal switch that shorts all segments of the commutator so that the motor operates as an induction motor once it has been accelerated to full speed. RS-IR motors have been used to provide high starting torque per ampere under conditions of cold operating temperatures and poor source voltage regulation. Few repulsion motors of any type are sold as of 2006.
14. Single-phase AC synchronous motors
Small single-phase AC motors can also be designed with magnetized rotors (or several variations on that idea). The rotors in these motors do not require any induced current so they do not slip backward against the mains frequency. Instead, they rotate synchronously with the mains frequency. Because of their highly accurate speed, such motors are usually used to power mechanical clocks, audio turntables, and tape drives; formerly they were also much used in accurate timing instruments such as strip-chart recorders or telescope drive mechanisms. The shaded-pole synchronous motor is one version.
Because inertia makes it difficult to instantly accelerate the rotor from stopped to synchronous speed, these motors normally require some sort of special feature to get started. Various designs use a small induction motor (which may share the same field coils and rotor as the synchronous motor) or a very light rotor with a one-way mechanism (to ensure that the rotor starts in the "forward" direction).
15.Torque motors
A torque motor. In this mode, the motor will apply a steady torque to the load (hence the name). A common application of a torque motor would be the supply- and take-up reel motors in a tape drive. In this application, driven from a low voltage, the characteristics of these motors allow a relatively-constant light tension to be applied to the tape whether or not the capstan is feeding tape past the tape heads. Driven from a higher voltage, (and so delivering a higher torque), the torque motors can also achieve fast-forward and rewind operation without requiring any additional mechanics such as gears or clutches. In the computer world, torque motors are used with force feedback steering wheels.
15. Stepper motors
Closely related in design to three-phase AC synchronous motors are stepper motors, where an internal rotor containing permanent magnets or a large iron core with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the motor may not rotate continuously; instead, it "steps" from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards.
Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions; more sophisticated drivers can proportionally control the power to the field windings, allowing the rotors to position "between" the "cog" points and thereby rotate extremely smoothly. Computer controlled stepper motors are one of the most versatile forms of positioning systems, particularly when part of a digital servo-controlled system.
Stepper motors can be rotated to a specific angle with ease, and hence stepper motors are used in computer disk drives, where the high precision they offer is necessary for the correct functioning of, for example, a hard disk drive or CD drive. Only very old harddrives (from the pre-gigabyte era) use stepper motors, newer drives use voice coil based systems.
Stepper motors were upscaled to be used in electric vehicles under the term SRM switched reluctance machine.
16. Permanent magnet motor
A permanent magnet motor is the same as the conventional dc machine except the fact that the field winding is replaced by permanent magnets. By doing this, the machine would act like a constant excitation dc machine (separately excited dc machine).
These motors usually have a small rating, ranging up to a few horsepower. They are used in small appliances, battery operated vehicles, for medical purposes, in other medical equipment such as x-ray machines. These motors are also used in toys, and in automobiles as auxiliary motors for the purposes of seat adjustment, power windows, sunroof, mirror adjustment, blower motors, engine cooling fans and the like.
The latest developments are PSM motors for electric vehicles. - High efficiency - Minimal locking moment and torque surface undulation - Small space requirements, compact dimensions - Low weight source [1]
17.Brushless DC motors
Many of the limitations of the classic commutator DC motor are due to the need for brushes to press against the commutator. This creates friction. At higher speeds, brushes have increasing difficulty in maintaining contact. Brushes may bounce off the irregularities in the commutator surface, creating sparks. This limits the maximum speed of the machine. The current density per unit area of the brushes limits the output of the motor. The imperfect electric contact also causes electrical noise. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance. The commutator assembly on a large machine is a costly element, requiring precision assembly of many parts.
These problems are eliminated in the brushless motor. In this motor, the mechanical "rotating switch" or commutator/brushgear assembly is replaced by an external electronic switch synchronised to the motor's position. Brushless motors are typically 85-90% efficient, whereas DC motors with brushgear are typically 75-80% efficient.
Midway between ordinary DC motors and stepper motors lies the realm of the brushless DC motor. Built in a fashion very similar to stepper motors, these often use a permanent magnet external rotor, three phases of driving coils, one or more Hall effect devices to sense the position of the rotor, and the associated drive electronics. The coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall effect sensors. In effect, they act as three-phase synchronous motors containing their own variable-frequency drive electronics. A specialized class of brushless DC motor controllers utilize EMF feedback through the main phase connections instead of Hall effect sensors to determine position and velocity. These motors are used extensively in electric radio-controlled vehicles.
Brushless DC motors are commonly used where precise speed control is necessary, computer disk drives or in video cassette recorders the spindles within CD, CD-ROM (etc.) drives, and mechanisms within office products such as fans, laser printers and photocopiers. They have several advantages over conventional motors:
• Compared to AC fans using shaded-pole motors, they are very efficient, running much cooler than the equivalent AC motors. This cool operation leads to much-improved life of the fan's bearings.
• Without a commutator to wear out, the life of a DC brushless motor can be significantly longer compared to a DC motor using brushes and a commutator. Commutation also tends to cause a great deal of electrical and RF noise; without a commutator or brushes, a brushless motor may be used in electrically sensitive devices like audio equipment or computers.
• The same Hall effect devices that provide the commutation can also provide a convenient tachometer signal for closed-loop control (servo-controlled) applications. In fans, the tachometer signal can be used to derive a "fan okay" signal.
• The motor can be easily synchronized to an internal or external clock, leading to precise speed control.
• Brushed motors cannot be used in the vacuum of space because they will weld themselves into an immovable position.
• Brushless motors have no chance of sparking, unlike brushed motors, making them better suited to environments with volatile chemicals and fuels.
Modern DC brushless motors range in power from a fraction of a watt to many kilowatts. Larger brushless motors up to about 100 kW rating are used in electric vehicles. They also find significant use in high-performance electric model aircraft.
18. Coreless DC motors
Nothing in the design of any of the motors described above requires that the iron (steel) portions of the rotor actually rotate; torque is exerted only on the windings of the electromagnets. Taking advantage of this fact is the coreless DC motor, a specialized form of a brush DC motor. Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. The rotor can take the form of a winding-filled cylinder inside the stator magnets, a basket surrounding the stator magnets, or a flat pancake (possibly formed on a printed wiring board) running between upper and lower stator magnets. The windings are typically stabilized by being impregnated with epoxy resins.
Because the rotor is much lighter in weight (mass) than a conventional rotor formed from copper windings on steel laminations, the rotor can accelerate much more rapidly, often achieving a mechanical time constant under 1 ms. This is especially true if the windings use aluminum rather than the heavier copper. But because there is no metal mass in the rotor to act as a heat sink, even small coreless motors must often be cooled by forced air.
These motors were commonly used to drive the capstan(s) of magnetic tape drives and are still widely used in high-performance servo-controlled systems.
19. Linear motors
A linear motor is essentially an electric motor that has been "unrolled" so that, instead of producing a torque (rotation), it produces a linear force along its length by setting up a traveling electromagnetic field.
Linear motors are most commonly induction motors or stepper motors. You can find a linear motor in a maglev (Transrapid) train, where the train "flies" over the ground.
20. Doubly-fed electric motor
Doubly-fed electric motors or Doubly-Fed Electric Machines incorporate two independently powered multiphase winding sets that actively participate in the energy conversion process (i.e., doubly-fed) with at least one of the winding sets electronically controlled for synchronous operation from sub-synchronous to super synchronous speeds. As a result, doubly-fed electric motors are synchronous machines with an effective constant torque speed range that is twice synchronous speed for a given frequency of excitation. This is twice the constant torque speed range as Singly-Fed Electric Machines, which incorporate a single active winding set. In theory, this attribute has attractive cost, size, and efficiency ramifications compared to Singly-Fed Electric Machines but Doubly-fed motors are difficult to realize in practice.
The Wound-Rotor Doubly-Fed Electric Machines, the Brushless Wound-Rotor Doubly-Fed Electric Machine, and the so-called Brushless Doubly-Fed Electric Machines are the only examples of synchronous doubly-fed electric machines.
21. Singly-fed electric motor
Singly-fed electric motors or Singly-Fed Electric Machines incorporate a single multiphase winding set that actively participate in the energy conversion process (i.e., singly-fed). Singly-fed electric machines operate under either Induction (i.e., Asynchronous) or Synchronous principles. The active winding set can be electronically controlled for optimum performance. Induction machines exhibit startup torque and can operate as standalone machines but Synchronous machines must have auxiliary means for startup and practical operation, such as an electronic controller. Singly-fed electric machines have an effective constant torque speed range up to synchronous speed (i.e., 3600 rpm @ 60 Hz and 2 Poles) for a given excitation frequency.
The Induction (Asynchronous) motors (i.e., squirrel cage rotor or wound rotor), Synchronous motors (i.e., field-excited, Permanent Magnet or brushless DC motors, Reluctance motors, etc.), which are discussed on this page, are examples of Singly-fed motors. By far, Singly-fed motors are the predominantly installed type of motors.
22. Dual mechanical port motor
The Dual Mechanical Port Electric Motors (or DMP electric motor) is considered a new electric motor concept. More accurately, DMP electric motors are actually two electric motors (or generators) occupying the same package. Each motor operates under traditional electric motor principles. The electrical ports, which may include electronic support, of the electric motors are tied to a single electrical port while two mechanical ports (shafts) are available externally. Theoretically, the physical integration of the two motors into one is expected to increase power density by efficiently utilizing otherwise wasted magnetic core real-estate. The mechanics of the integration, such as for the two mechanical shafts, may be quite exotic.

Nanomotor constructed at UC Berkeley. The motor is about 500nm across: 300 times smaller than the diameter of a human hair
Researchers at University of California, Berkeley, have developed rotational bearings based upon multiwall carbon nanotubes. By attaching a gold plate (with dimensions of order 100nm) to the outer shell of a suspended multiwall carbon nanotube (like nested carbon cylinders), they are able to electrostatically rotate the outer shell relative to the inner core. These bearings are very robust; Devices have been oscillated thousands of times with no indication of wear. The work was done in situ in an SEM. These nanoelectromechanical systems (NEMS) are the next step in miniaturization that may find their way into commercial aspects in the future.
Notice: The thin vertical string seen in the middle, is the nanotube to which the rotor is attached. When the outer tube is sheared, the rotor is able to spin freely on the nanotube bearing.

CURRENT IN THE INDUCTOR IN TERMS OF THE VOLTAGE ACROSS THE INDUCTOR

2009-06-21T23:53:00.000-07:00

CURRENT IN THE INDUCTOR IN TERMS OF THE VOLTAGE ACROSS THE INDUCTOR

V=L di/dt
Vdt=L (di/dt) dt
∫ di=∫ 1/L v dtI=1/L ∫ v dt + i(to)

Ex. The voltage pulse applied to the 100 mH inductor shown is 0 for t< 0 and is given by the expression

v (t) = 20 t e (-10t) for t> 0. Also assume i= 0 for t≤0.

Solution:
a) The inductor current as a function of time.

Assignment:
The voltage pulse applied to the 100 mH inductor is 0 for t<0 and is given by the expression
V(t)=10te-20t for t>0 . Also assume i=0 for t≤0.
Required:
a) The inductor current as a function of time t≤0.
b) The time when voltage is maximum.
c) maximum voltage.

Ans:a)i=-50e -20t -2.5 e -20t +2.5 b) t=0.5 S
c) 0.18394 V

course outline in basic electronics ee412

2009-06-16T17:32:00.000-07:00

COURSE OUTLINE IN EE 412

Course Number: ECE 412
Course Title: Basic Electronics
Credit: 4 units (3 hrs Lecture, 3 hrs Laboratory)
Pre-requisite: Co-requisite:
Course Description: This course provides an introduction to Basic Electronics. Emphasis is placed upon the development of diodes , transistors,Silicon Controlled Rectifier(SCR), thyristors , relays and triacs

Inclusive Date Topics to be covered in the Course: No. of Hours

I. Types of Diode
1. Theory and Operation of diode
2. Types of diodes
3. Series and parallel circuit
4. Rectifiers
5. Halfwave
6. Full wave rectifier
7. Voltage rectifiers
Prelim Examination

II. TRANSISTOR
1. THEORY AND OPERATION OF TRANSISTORS
2. Types of transistors
3. Transistor circuits
4. Relays

III. SCR AND TRIACS
1. Theory and operations of SCR
2. Theory and operations of Triacs
5. Electrical Characteristics of Triacs
6. Triggering methods for triacs

Basis Grading:
Passing Cut-off Score = 60%
Subject Grade = Lec (75%)+ Lab (25%)
Lec Grade = ((PG+ MG + FG)/3)
Lab Grade = ((PG+ MG + FG)/3)

Lecture: Per Period Laboratory: Per Period
Quizzes 40% Lab Work 30%
Lab Exam 20%
Major Exam 60% Practical Exam 50%
100%
100%

Schedule of Major Examination:
Prelim Exams July 25-26, 2005 Mon. & Tue.
Midterm Exams September 1-2, 2005 Thurs. & Fri.
Final Exams October 10-13, 2005 Mon – Thurs.

COURSE OUTLINE POWER ELECTRONICS

2009-06-15T09:45:00.000-07:00

COURSE OUTLINE IN PELECT2

Course Number: PELECT 2
Course Title: Power Electronics
Credit: 3units (3 hrs Lecture)
Pre-requisite: Co-requisite:
Course Description: Power Electronics deals with the design and applications of power semiconductors converters, and to analyze converter characteristics in order to understand how these converters interact with the electric utility grid with the various load applications.
Inclusive Date Topics to be covered in the Course: No. of Hours
I. PNPN AND OTHER DEVICES
1. Introduction
2. SCR
3. SCS
4. GTO
5. LASCR
6. Shockley Diode
7. Triac

II. POWER COMPUTATIONS
1. Introduction
2. Power and Energy
3. Inductors and Capacitors
4. Energy Recovery
5. RMS
6. Apparent Power and Power Factor
III. Half wave Rectifier

1. Introduction
2. Resistive Load
3. Resistive-Inductive Load
4. Half-Wave rectifier with a capacitor
5. Controlled Rectifier

IV. Full wave rectifier

1. Introduction
2. Single Phase Full wave rectifier
3. Controlled Full wave rectifier
V. AC VOLTAGE CONTROLLER: AC TO AC CONVERTER
1. INTRODUCTION
2. SINGLE Phase AC Voltage controller

VII DC Converter

1. Linear Voltage regulator
2. Basic switching converter
3. Buck Converter
4. Boost Converter

VIII. DC Power Supplies
1. Introduction
2. Transformer Models
3. Flyback converter
4. Forward converter
5. Double Ended Converter
6. Push Pull converter

Basis Grading:
Passing Cut-off Score = 60%
Lec Grade = ((PG+ MG + FG)/3)

Lecture: Per Period
Quizzes 40%
Major Exam 60%

Schedule of Major Examination:
Prelim Exams
Midterm Exams
Final Exams

INSTRUCTIONAL MATERIALS
TEXT: Power Electronics
By : Rashid

Electrical Machinery Generalization

2009-06-11T22:41:00.001-07:00

LEC 1

Electrical Machinery Generalization

Types of Rotating Machines

1. Generators-mechanical energy is converted to electrical energy.
2. Motors-electrical energy is converted to mechanical energy.
3.Rotary converters-electrical energy of one form is changed into electrical energy of another; the usual arrangement is to change ac energy to dc energy ;although the reverse is sometimes done.
4.Frequency Converters- to change ac electrical energy at one frequency into ac electrical energy at another frequency.

Primemover- a mechanical machine that drives(rotated) the electric generator.

Ex. steam turbine,gasoline engine or electric motor

* generator action can take place when and only there is relative motion between conducting wires(usually copper) and magnetic lines of force

parts of electric generators

1) even set of electromagnets(field poles)

Field Poles- is built of a stack of steel laminations having good magnetic qualities.

Types of Field Poles

salient pole field-when driven by a slow speed prime mover,the electromagnets are bolted to a hub fastened to the shaft so that they project outward toward the stationary armature core

non salient pole field-the field winding is placed in a slotted core when driven by a high speed turbine.

2) laminated steel core containing current carrying copper wires(armature)
Armature windings-it is where the voltage is generated in the generator or where the torque is develop in the motor.

Assignment: Download lec 1 and the course outline .Register your name by adding in the MEMBERS,JUST CLICK FOLLOW RIGHT SIDE PORTION.

COURSE OUTLINE ENERGY CONVERSION

2009-06-11T22:18:00.000-07:00

COURSE OUTLINE IN EE105

Course Number: EE 105
Course Title: ENERGY CONVERSION
Credit: 4 units (3 hrs Lecture, 3 hrs Laboratory)
Pre-requisite: Co-requisite:
Course Description: This course provides an introduction to energy conversion. Emphasis is placed upon the development of motors and generators. Topics include: Electrical Machinery Generalization DC Generator and Motor Principles Generator and Motor Constructions, DC Generator Characteristics
DC motor Characteristics Efficiency, Ratings and Applications of Dynamos AC Generators, Transformers, Batteries.

Inclusive Date Topics to be covered in the Course:
I. Electrical Machinery Generalization

1. Rotating Electrical Machines
2. Armature Windings
3. Field poles
4. Types of DC Generators
5. Voltage Characteristics of DC motors
6. Transformers

QUIZ 1
II. DC Generator and Motor Principles

1. Principle of Generator Action
2. Faradays Law
3. General Voltage Equation for DC Generator
4. Direction of Generated Voltage
5. Lorentz Law
6. Lenz Law
7. Force and Torque Developed by DC Motors

QUIZ 2

QUIZ 3

III. Generator and Motor Constructions

1. Types of Armature windings
2. Coin span for all types of winding
3. Commutator pitch for lap windings
PRELIM EXAM

QUIZ 4
IV. DC Generator Characteristics
1. Types of DC Generators
2. No load characteristics of generators
3. Degrees of Compounding Adjustment

QUIZ 5
V. DC motor Characteristics
1. Operating differences between motors and generators
2. Classification of Dc motors
3. Counter EMF
4. Voltage generated by a motor
5. Starting a DC motor

QUIZ 6

VI. Efficiency, Ratings and Applications of Dynamos
1. Power losses in dynamos
2. Efficiency of Dc motors and generators
3. Importance of Efficiency
4. Rating of Generators and motors

QUIZ 7

VII. AC Generators

1. Alternator Construction
2. Frequency of AC generators
3. The Revolving Field

QUIZ 8

VIII. Transformers

1. Transformer Action
2. Transformer Construction
3. Transformer voltage and the general transformer equation
4. Voltage and current ratios in transformers

QUIZ 9

IX. Batteries

1. Primary Cells
2. Lead Acid batteries
3. Specific Gravity
4. Hydrometers
5. Water for Batteries
6. Capacity of a batteries
7. Maintaining lead-Acid Cells
8. Other chemical Cells

Basis Grading:

*quizzes will be unannounced
*expect a quiz after the topic
Passing Cut-off Score = 75%
Subject Grade = Lec (75%) + Lab (25%)
Lec Grade = ((PG+ MG + FG)/3)
Lab Grade = ((PG+ MG + FG)/3)

Lecture: Per Period Laboratory: Per Period
Quizzes 40% Lab Work 30%
Lab Exam 20%
Major Exam 60% Practical Exam 50%
100%
100%

Schedule of Major Examination:
Prelim Exams July 25-26, 2005 Mon. & Tue.
Midterm Exams September 1-2, 2005 Thurs. & Fri.
Final Exams October 10-13, 2005 Mon – Thurs.

INSTRUCTIONAL MATERIALS:
TEXT: Electrical Machineries
By: Charles Siskind

REFERENCES: Industrial Electronics
By: Timothy J. Maloney

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