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1500 questions
42
votes
5 answers
Who receives the value returned by main()?
I know that in computers, value returned by the main() function is received by the operating system.
But, what happens in the main() function of a microcontroller?
user18118
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42
votes
3 answers
Does Bluetooth interfere with WiFi?
I've read that WiFi b/g/n is using 2.3995 to 2.4845 GHz.
Bluetooth is in between: 2.4000 to 2.4835 GHz.
So what will happen when I put a Bluetooth sending device next to a WiFi sending device?
Will the two devices be aware of each other (like two…
zomega
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42
votes
3 answers
How is wristwatch with 10 years battery life possible?
Turns out Casio offers a handful of wristwatches with "10 year battery life". The claim is that thanks to "an advanced technology" the battery life in those watches is extended to ten years.
Now if you look at different models you see that they are…
sharptooth
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42
votes
8 answers
How are current and voltage related to torque and speed of a brushless motor?
I know that electric vehicles have different performances depending on battery and motor, but it's not clear how electrical and mechanical units are related.
Will a 100V motor raise against slopes better than a 50V motor?
jumpjack
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42
votes
6 answers
Can an audio circuit be powered by a switched-mode power supply?
Most audio circuits are powered with large, heavy transformers and a small ripple after smoothing. SMPS are smaller and more efficient. EMI can be shielded by a metal enclosure and the output filtered for noise suppression.
Especially where the…
Rob Kam
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42
votes
9 answers
What sensor to choose to track human presence indoors?
This is a hobby project about home automation. The idea is that of distributed system of cheap microcontrollers that take measurements, communicate, output data and control appliances.
One important task that this system should perform is detect at…
Vorac
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42
votes
4 answers
Why are LEDs on most embedded designs inverted?
I noticed, that on all my evaluation boards that I had up to this point in time. The LEDs were all connected in active low to the Microcontroller Port.
I understand that from a safety view it's better to have active low RESET lines and such. But…
anyone
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42
votes
3 answers
How do GPS satellites refresh their clocks
How do GPS satellites keep their on board clocks accurate? I assume that they need to get update from a base station. But how do you make sure that after the update all the satellites are synchronized, i.e. there isn't any phase shift.
You have…
user110971
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42
votes
3 answers
What is the purpose of a buffer gate?
As I understand a buffer gate is the opposite of a NOT gate and does not change the input:
However I sometimes see buffer gate ICs used in circuits and to an inexperienced eye they seem to do nothing at all. For example recently I've seen a…
I have no idea what I'm doing
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42
votes
10 answers
Is current source also a voltage source?
I'm confused between current and voltage sources; I get the text book definition but I am not able to understand real world difference. To me both current and voltage sources seem as the same. I understand that ideal sources doesn't exist. What is…
user3551094
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42
votes
1 answer
Where is the Eagle component library for 0.1" breakaway headers?
I want to put some breakaway headers into my Eagle CAD file. By that, I mean these:
Does Eagle come packaged with a library for these? If so, what is the part called, and which library is it in?
Eric
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42
votes
2 answers
Correct formula for LED current-limiting resistor?
I'm trying to work out what value resistor to use in a LED circuit. The equation I'd use to do this is:
$$ R = \frac{V_{cc} - V_f}{I_f} $$
Seems logical, and makes complete sense. The answers to the question How do I calculate the resistor value for…
Jeremy Kerr
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42
votes
5 answers
Why use complex numbers to represent amplitude and phase of AC
Why is it that in AC circuits, sine waves are represented as a complex number in polar form? I don't logically understand from a physical perspective why there is an imaginary part at all. Is it purely from a mathematical point of view to make the…
Prevost
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41
votes
3 answers
How do Circuit Simulators actually work?
I recently had the opportunity to play around with LiveWire, which is a circuit simulator and began wondering how exactly they computed the voltages across each component and the current going through each track of wire.
I have only been taught…
Thomas Russell
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41
votes
6 answers
How fast does electricity flow?
I get confused on the low-level physics of electricity from time to time. It came up in "Which way does electricity power a circuit," and I don't totally get it.
How fast does electricity flow? Is the speed of an electron different in say a resistor…
travisbartley
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