Study and applications of electricity, electronics, and electromagnetism. Use this tag when someone who has trained as an electrical engineer is likely to be able to answer your question.
Questions tagged [electrical-engineering]
1468 questions
58
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4 answers
Why is kVA not the same as kW?
I thought my electric car charging unit uses 6.6 kW of power. However, I found the label and it actually says 6.6 kVA. When I saw this I thought something along the lines of...
Well, $ P=VI $, therefore kVA must be the same thing as kW... strange,…
jhabbott
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24
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Why doesn't a lightning strike destroy the lightning rod?
Lightning strikes have been known to cause massive amounts of damage. The stats on a lightning bolt are:
current levels sometimes in excess of 400 kA, temperatures to 50,000 degrees F., and speeds approaching one third the speed of light
These are…
hazzey
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18
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4 answers
Why does the microwave plate start in a random direction?
...or what type of motor is used there?
I found this type of motor - usually powered with low-voltage AC (~12V), but at times with 230V, in several appliances that require very slow rotation and sometimes a fair momentum - a color-shifting lamp, the…
SF.
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How is the wattage of an incandescent light fixture determined?
I've seen light fixtures with varying wattage rating. From 30W to 100W even though the actual socket is the same.
What is the limiting factor, why can't I put say a 75W bulb in a fixture rated at 50W?
ratchet freak
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7
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3 answers
Why do we need to shut down power generators if we are producing more power than the grid requires?
Why do we need to shut down power generators if we are producing more power than the grid requires?
How it will damage the system if they are not shut down?
Fred
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3 answers
What is the best way to control brightness of a LED?
LED brightness can be controlled using digitally controlled potentiometer such as a Microchip MCP413X or a PWM signal. In both cases the signal will be controlled/ generated from a micro-controller. Which method is better using a digitally…
Mahendra Gunawardena
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7
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3 answers
Does a 3-phase electricity grid need to be synchronised and are the phases split between houses?
Note: This may be UK-specific, I'm not sure.
I overheard part of a conversation about 3-phase electricity, one guy was saying that mains generators use 3 coils (or something) and as it spins it produces 3 different waves of alternating current that…
jhabbott
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6
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3 answers
Electromechanically open and close a small, hinged door?
I have a chicken coop I plan on modifying to automatically open and close the door at dawn and dusk.
What sort of actuator or mechanism would be appropriate for operating the small, side-hinged door?
Constant power is not available (solar) plus it…
bufferout
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If my electronics are outdoors in a ventillated NEMA 4 enclosure, should I conformal coat my circuit boards?
I'm considering putting a circuit board in a ventilated NEMA 4 enclosure outdoors. I'm a little concerned about humidity and condensation inside the enclosure. Do I need to conformal coat my circuit boards, or take any other precautions?
Stephen Collings
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6
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4 answers
Why do we prefer resistance over conductivity in describing Ohm's law?
In my mechanical engineering training , I've noticed that many constitutive relations (e.g. fourier law, poiseuille law, hooke's law) involve a flux which increases as the material parameter increases. In heat transfer and fluid flow, this is…
Paul
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5
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1 answer
Why is capacitor 2 not grounded on this board?
I'm building a APRS tracker for a high altitude balloon and am tracing the voltage as it's not powering up. I'm confused why it seems that this capacitor's ground appears to not be connected to anything. topside of board
Jim Swarthout
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5
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1 answer
Convert 60hz 120Vrms to 24khz 120Vrms
I would like to create an interface that increases the frequency out of the wall, 60 hz, to 24khz. I have chosen 24khz as the operating frequency of an induction heater I am planning on building and I would like some advice as to how I should go…
Toroid Tank
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5
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2 answers
Why Ceramic Capacitors Are Not Rated Directly Like Electrolytic Ones?
I want to know why ceramic or disk capacitors are not rated directly like electrolyte ones? Is it just a convention or some other reason is behind this? Like, the ceramic ones are rated as 762k. then the value of the capacitance is 7600pF. (7-1st…
Dwiparna Datta
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5
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1 answer
Light signal isolation
It is possible with a microphones array to isolate a sound coming from a direction. Is it possible with an array of photo diodes to isolate a light signal coming from one direction?
For example having 4 photo-diodes oriented at the same direction,…
Mehdi
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5
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How to remove potting material from an electronic package?
I have an electronic device that uses black potting materiel similar the one below to I believe to protect the electronic components from elements.
I would like to safely remove this material. This material might be some type of epoxy. There are…
DiaperHands
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