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Engineering Stack Exchange

Questions tagged [electrical-engineering]

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.

1536 questions
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Why do color TVs make black and white snow?

If you let a color TV display something from an unplugged display port, it displays snow, right? Randomly varying black or white pixels on the whole screen. My guess was that the television was decoding the noise from the unplugged wires as a video…
Axel B
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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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Why do cars have mirrors for rear view rather than cameras?

Despite having so much technological advancement, I wonder why cars still uses mirrors (right and left side of the driver) for the rear view. These mirrors can be easily replaced by cameras and monitors (display for the driver). I noticed such…
parag
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My customer wants to use my products to do something unsafe. What is my ethical obligation?

We sell products that attach to a motor drive's DC bus. We also formerly sold diode kits that let you hook one product up to multiple drives. We stopped selling those diode kits because they were unreliable with modern hardware, and we had better…
Stephen Collings
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Why are two wires used in railway overhead equipment?

While watching the train videos, I came across these overhead wires. After searching on the internet, I found that both catenary and contact wires carry the same voltage and are connected by vertical wires called "droppers" at intermediate points…
mech_duck
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3 answers

Calculating pitch, yaw, and roll from mag, acc, and gyro data

I have an Arduino board with a 9 degree of freedom sensor, from which I must determine the pitch, yaw, and roll of the board. Here is an example of one set of data from the 9-DOF sensor: Accelerometer (m/s) $\text{Acc}_{X}$ = -5,85 $\text{Acc}_{Y}$…
MaltDew
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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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Would it make sense to have a 12V lighting circuit in a house?

Modern LED bulbs must convert the standard household supply (for example $240\text{V AC}$ in the UK) into a DC supply at a lower voltage (usually $12\text{V DC}$ I think) for the LED array. This is done on a per-bulb basis. Does this waste much…
jhabbott
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How does a traffic light sense the proximity of vehicles?

Some traffic lights don't operate periodically but instead detect when a car is close by and then turns green. I have heard that they use a magnetic sensor embedded in the road to sense cars as they come near. Is this correct? Do they use other…
FullmetalEngineer
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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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What is it about the cabin electrical supply on cruise ships that makes surge protectors dangerous?

Surge protectors are banned on cruise ships, and so are confiscated during boarding. Extension cords and cube taps etc. are discouraged, but not banned. I'm asking specifically about surge protector incompatibility, and would like an answer that…
Ray Butterworth
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What is this small rotating part from a cell phone?

What is this tiny rotating piece of hardware that I found inside my Samsung GE1202? It has E9C written in blue on it.
PyRoss
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15
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Can I use a ultrasound sensor to measure water level?

If I use an ultrasonic sensor will it detect the water level? I was thinking about a product to read water level on water boxes (common in Brazil). I researched about instrumentation for this measure, and I think that an ultrasonic sensor is the…
Henrique Oliveira
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Quantifying inertia on the electricity grid

A lot of discussion about the modernisation of electricity systems is about "inertia". This is usually a qualitative discussion about how turbines (in hydro, coal & gas plants) with lots of kinetic energy in the form of angular momentum and fast…
410 gone
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What limits a power plant's load gradient?

Each power plant has a load gradient characteristic, describing to what extent it can change the output of its generators in a given timeframe. Reading the literature, I know that, for example, a gas turbine power plant has a vastly higher load…
Technaton
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