All Questions
Tagged with electrical-engineering power
56
questions
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Converting string vibration to electricity
Is there a device that can use the energy from a vibrating string (i.e. guitar string, etc.) to produce enough electricity to power a small LED?
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47
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Converting RMS to Maximum Power
If I have a sinusoidal voltage signal of amplitude $V_m$ driving a resistance $R$, what is the relationship between the RMS power $P_{rms}$ and the maximum power $P_{max}$ delivered to the resistance?
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Wind triboelectricity shakers in series
I've seen shaker generators made with small plastic hemispheres with aluminum foil stuck on inside both, and a small ball wrapped in tape put in and sealed up. Then the shaker is vibrated and it ...
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296
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Can over correcting power factor cause damage to equipment?
If you over-correct your power factor, that is your power factor is leading, not lagging as expected by the utility, can you damage your (as opposed to the utility's) equipment?
As we are all aware, ...
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Standards for the sign of the power factor; IEC and IEEE; is there an ANSI standard?
Working with some power factor measurement, this article (reference: https://www.se.com/ww/en/faqs/FA212521/) has this interesting bit:
Issue: Understanding and interpreting the sign of a power factor ...
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36
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Peculiar step-down transformer behavior
I have wired several loaded transformers and when calculating power on H vs X side by multiplying current times voltage the wattage is not even close to equal with the H side having 2 to 3 times more ...
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63
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Why do identical-looking power plugs randomly not fit in some sockets in the same power strip?
This has bothered me for many years, but I'm only now coming around to ask about it.
I don't know if this is unique to Sweden or something, but for whatever reason, when I try to plug things into the ...
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208
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Can I use a PWM motor regulator to control a LED string?
I recently bought some LED Christmas lights, but they are too bright. So I was thinking that maybe I could regulate the output by using a PWM regulator? My LED lights have an output of 30V from the ...
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55
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Power systems unclear voltages
I was looking at this problem:
"A balanced delta connected impedance load with (12+j9)Ω per phase is supplied by a balanced three-phase 60 Hz, 208-V source "
I do not wish to ask for help at ...
- 275
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1k
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Line to neutral voltage in three-phase power systems
I have the book "Power system analysis and design" by Sarma.
In his intro to balanced LN voltages, in chapter 2 p62 he states:
$$V_{LL} = \sqrt{3} V_{LN} \angle30º$$
but later in the chapter,...
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-1
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Battery size and maximal power output [closed]
Generally how does the size of the battery affect its maximal power output(together with other factors like materials, for instance)?
Under the current engineering technology and with any possible ...
-1
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1
answer
85
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What is the maximum distance for eavesdropping? [closed]
There is a closed question
https://physics.stackexchange.com/questions/276667/what-is-the-maximum-distance-for-eavesdropping-sound-waves
on Physics Stack Exchange and I thought this might fit better ...
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0
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97
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Devices powered and charged via electricity generated by human body
I came across articles like:
https://www.sciencedaily.com/releases/2021/02/210210142049.htm
https://pubmed.ncbi.nlm.nih.gov/27836601
and
https://www.dailymail.co.uk/sciencetech/article-2004801/Weve-...
1
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5
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How can I add the torque of multiple gears?
If I have 3 gears meshed with a gear in the center of the 3 gears as shown in the picture. all of those 3 gears are connected to different power sources. They are free to rotate in the same direction ...
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How are NASA's mars rovers able to operate with such little energy?
The latest Mars rover being, NASA's Perseverance, uses the Multi-mission radioisotope thermoelectric generator, which has a maximum power output at the beginning of it's operational life of 125 watts, ...
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