Questions tagged [power-electronics]

Refers to the conversion of electric power by using solid state components such as semiconductors. Can also generally apply to the field of electrical engineering which works with power electronics.

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77
votes
11answers
31k views

Where does electricity go after being used?

For a very long time I have been wondering, where does electricity go after being used? When I use my tablet it runs from a battery. Where does the power go?
34
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2answers
10k views

Weird resistor with dots around it on the schematic

I was looking through the LTC4041 datasheet and saw this: The 10mOhm resistor with the two nodes really close to it - is that a "special" resistor or something? Why have they drawn it like that?
33
votes
8answers
5k views

Why do devices stop operating properly in extreme cold?

I have noticed that a lot of smart phones say that they won't operate under -4 degrees F (-20 degrees C). Can anyone explain to me what happens when the phones get cold that stops them from operating?
33
votes
3answers
6k views

Why does power dip during a lightning storm?

If lightning were to strike power lines, wouldn't you expect it to increase the power, and hence your room lights get brighter? Why do they go dim for 1 second at a time?
26
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4answers
3k views

Spacecraft Power Supply Frequency

I know that aircraft sometimes employ a 400Hz AC system to save weight on transformers, so I'd imagine that spacecraft might employ a similar technique. I'm wondering if anyone in the aerospace field ...
19
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10answers
7k views

Are all electrical sockets of my house in the same phase?

Most countries use AC power that is supplied to each house. This AC power is in the form of a sine wave. Suppose I have 2 electrical power sockets in two rooms that are at the opposite ends of my ...
15
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3answers
40k views

What is Overmodulation?

The Wikipedia article is very short and doesn't explain the concept very well, and there aren't any other sites that I can find that give a simple explanation. What does it mean by 100% modulation? I ...
15
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5answers
1k views

Voltage regulator from first principles - why is power dumped in the transistor?

I'm trying to further my understanding of electronics, so I decided to try to design a fixed voltage regulator capable of supplying an amp or so. I put this together from first principles without ...
14
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2answers
3k views

IGBT vs. Power MOSFET for switching applications. Where to draw the line?

For lower breakdown voltages, a power MOSFET is clearly the device to go for, in view of its higher efficiency, higher commutation speed and lower price. Where should the line be drawn, upwards of ...
14
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3answers
1k views

Why an electrician wiring error could make a PC's USB shield be at 120V when it should be grounded

I almost had a serious electrical accident last week when I was trying to use an oscilloscope to test out a circuit a student had built. I had the scope plugged into a floor outlet, and the circuit ...
14
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1answer
992 views

What does a black bar across transformer symbol designate?

What does a black bar across a transformer symbol designate? This appears in a power electronics context, and in particular in this case with substituting a DC transformer as an equivalent circuit ...
13
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4answers
59k views

How do I find the voltage range for an unknown DC motor?

I have a small unmarked motor with a burned out speed controller board. I'm able to figure out that the motor is a DC motor because it has two wires coming out of it and there's a rectifier on the ...
12
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6answers
4k views

What kind of hardware implements Fourier transform?

I looked around online but I found nothing relevant. It is very difficult for an electronic device to decompose a signal in different frequencies. How this is done at the bare metal level? Any ...
12
votes
6answers
4k views

How To Know If a Fuse Will Work Properly?

I want to know what kind of periodic test we use to test if a current-limiting fuse will normaly open and protect an electronic circuit (a battery charger) if a failure occur (short circuit or over ...
12
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4answers
10k views

Why is flyback air gap needed for energy storage?

Why do so many sources say something along the lines "since a flyback transformer stores energy, an air gap is needed"? I have seen this reasoning in textbooks and app notes. I thought air gaps ...
11
votes
9answers
13k views

Which method or component is best to regulate 42 to 3.3 V?

I am using a 36 V battey pack (10s 2.5 A each cell 3.6V.) Its maximum voltage is 42 V. I am using a STM32 microcontroller whose input is 3.3 V. I am designing a PCB in which the power supply is drawn ...
11
votes
5answers
3k views

Why/when is AC-DC-AC conversion superior to direct AC-AC conversion?

I am currently studying wind power and the power electronics used for it. In wind power a generator is driven by wind, thus the resulting power is of widely varying frequency and amplitude. The power ...
11
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2answers
3k views

What is the difference between CPU transistors and generic ones?

Recently I had to build a h-bridge driver for my project, wireless power transmission. I learnt that I needed to have dead-time in my PWM signal given to IR2110, which doesn't have any dead-time ...
11
votes
5answers
7k views

Will a battery short out when the terminals are directly connected together or will internal resistance save it?

I intended to make a simple electromagnet, then I saw this video where the user is connecting wires together with no resistance at all. I was wondering why it doesn't short out and make the battery ...
11
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1answer
3k views

Symbols: Double-arrow circle enclosed “10” on electronic appliances

What does the symbol that says 10 inside the double arrowed circle mean? I have seen a similar symbol on another appliance that had the number 25
11
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1answer
866 views

Why do power diodes have a p+ n- n+ construction and why not p+ p- n+?

I've been learning about power diodes and how they differ from low power diodes with the addition of a lightly doped n-type layer. This n-type layer improves the breakdown voltage rating of the ...
10
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5answers
10k views

What happens if I connect a low voltage rated capacitor to a high voltage?

Given that c=q/v even if I connect it to a higher V, its charge Q may decrease proportionally right? So why should it damage my capacitor? or will the internal electric field get too high and cause ...
10
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7answers
98k views

Why does the USA use 110V and UK use 230-240V?

Why does the USA use 110V and UK use 230-240V? What are the advantages? Explain me with calculation. Why do they use different frequencies like 50Hz, 60Hz? What is the reason?
9
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6answers
2k views

What are the best old electrical appliances to extract electronic components from? [closed]

I would like to build some simple drones and robots which I will be controlling using a microcontroller. Instead of buying expensive brand new components, I prefer to look for old electrical ...
9
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3answers
7k views

What is a good power electronics textbook? [closed]

I really want to learn as much as I can about power electronics, switching mode power supplies, and overall analog design. Unfortunately my universities computer engineering program is still ...
9
votes
7answers
782 views

Software suggestions for electronic simulations?

I am a beginner in EE engineering and want to use a software where I can analyze signals or even motor speeds, power electronics ect. But the Spice programs looks so boring and detailed for me. Maybe ...
9
votes
1answer
3k views

What is this high power switch symbol?

I am a medical physicist, and I program software for MRI scanners as well as develop electronic devices that interact with them. Because of the way MRI works, it is necessary to use very large power ...
8
votes
7answers
975 views

Isn't current flow a wrong term?

In most text books and other electronics material it's said current is flowing through the circuit. Isn't this wrong? As current is flow of charge. Is there anything such as flow of flow of charge?
8
votes
3answers
2k views

Discharging one side of a capacitor?

What I'm asking about is if it's possible to discharge one side of a capacitor. I've found a question about that, but I also found the answers to be a little unclear or questionable. I imagine that ...
8
votes
2answers
492 views

What's the easiest way to prevent a voltage input getting higher than a fixed value?

I just got a DC-DC step-up converter for my laptop, and I want to make double sure in case it malfunctions it will never affect my laptop. I am looking for an extra security device to prevent the ...
8
votes
2answers
916 views

dual of voltage doubler

Voltage doublers, like those close to be one stage of Cockroft-walton multipliers, are well known. They allow to double the voltage of an AC input and can be useful at the output of a transformer for ...
7
votes
2answers
3k views

Does solder expire?

I have some solder that is past the "expiration date" on it. How does solder expire? Is it still good? What happens if I use it? It seems odd that solder could expire, so I'm just looking for some ...
7
votes
2answers
7k views

Why is it desirable to inject reactive power into a transmission system?

This website explains the basics of FACTS technologies and how they can be used to exchange active and reactive power with the transmission system, namely: SSSCs - can exchange active and reactive ...
7
votes
1answer
686 views

What does sequences like 1-3, 1-10, 1-3-10 etc in a spectrum analyzer mean?

I have read in a paper explaining spectrum analyzer basic 'When selecting the RBW(resolution BW), there is usually a 1-10 or a 1-3-10 sequence of RBWs available. More RBWs are better because this ...
7
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2answers
1k views

H bridge not switching correctly - Induction heater

I've been working on an induction heater over the last few months and have had varied success. I can drive about 600W through it but as I begin to push past this point it isn't long until one of the ...
6
votes
3answers
1k views

So why aren't supercapacitors used more often? [closed]

I've recently found out that supercapacitors (C >= 1F or so) are actually a thing. I went searching for their advantages and disadvantages. They don't hold as much energy as a battery, but can ...
6
votes
5answers
26k views

What do you mean by a Wattage of an incandescent bulb?

How do I interpret the wattage of a bulb. For example when it is said that the bulb is rated for 60 W , what does that mean?
6
votes
4answers
2k views

What is so special in the power MOSFETS IRFD120 and IRFD110?

I was trying out a hobby project and I was using the IRFD120 and IRFD110 power MOSFETs to control a motor. The transistors worked pretty fine and we simply ran out of them. When I went to buy some ...
6
votes
2answers
1k views

For a MOSFET, does capacitive gate current only flow through to the source?

Everywhere states that a MOSFET has no current at the gate. However, this is not true since, during the time the gate capacitance charges up to reach the certain voltage threshold, the current is ...
6
votes
4answers
2k views

Indicator light circuit

I'm an electrician and my work is to maintain boats. I have a problem. On the boats are sailing lights, and for each sailing light is another light inside the boat that tells you if the sailing ...
6
votes
3answers
2k views

Is it safe to use series polarized capacitors to form non-polarized capacitors to be used for higher rated voltage?

simulate this circuit – Schematic created using CircuitLab It is known that we can use series capacitors to increase rated voltage. But I want to know how far we can push this feature to? ...
6
votes
2answers
617 views

Regarding Ferrite Bead

What is a ferrite bead? How is it different from an inductor? How is it rated? What are its important parameters? What allows me to chose between an inductor or ferrite bead to filter out frequencies ...
6
votes
4answers
546 views

Multimeter measurement

Looking for help with reading my multimeter. I would think by moving from 20 to 200, the decimal place would just shift one place. Why when I switch do I get a reading of 20ma vs 10ma?
6
votes
3answers
2k views

Understanding Boost Converter

Theres a very good explanation for the Boost Converter on Wikipedia. But it is a very mathematical explanation. How would you explain the Boost converter to a non Math person like me?
6
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2answers
2k views

Which one is the correct symbol of enhancement type MOSFET?

I studied MOSFET from ' Electric Devices and Circuit Theories by Robert L. Boylestad ' The symbols of depletion type and enhancement type MOSFET are given below from the book. But recently, in ...
6
votes
4answers
422 views

Removing output voltage ripple in high voltage outputs

I am looking to reduce the voltage ripple on a DC/DC converter operating at 5kV. I have looked extensively on the internet and have found multiple ways to reduce output voltage ripple, an ...
6
votes
2answers
5k views

Why do we use a diac for triggering a triac?

I mean, Wouldn't it be possible to give a gate pulse on triac directly? I have seen in many phase control application circuits like fan speed control,the usage of diacs to trigger a triac.
6
votes
2answers
14k views

Calculating a burden resistor for a current transformer

Background: I follow a reference design for a single phase power meter (230 V, max 3 A). The below circuit is to measure current via a current transformer. A current transformer will be ...
6
votes
5answers
1k views

The path of electrons in AC circuit?

I have a question regarding the AC circuit shown below. If we ignore the voltage drop caused by the long cable, I think the device will work and the circuit can be considered as a closed circuit. Now ...
5
votes
2answers
23k views

Role Of Emitter (By Pass) Capacitor

What is the importance of Bypass capacitor of Common-emitter amplifier? Will the gain be reduced when it is removed?

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