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1500 questions
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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41
votes
4 answers
How to synchronize two microcontrollers to micro-second accuracy?
I need to synchronize two micro-controllers so that they can measure the speed of propagating waves. The time delay measurements need have microsecond accuracy (error less that 1/2 of a microsecond).
I have two micro-controllers (ATmega328) which…
Kevin
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41
votes
8 answers
Why put a resistor in series with signal line?
A lot of times in circuits I see a resistor placed in series in a signal line and sometimes even in series with an MCU's VDD line. Is the intention of this to smooth out noise in the line? How is this different from using a small cap, like a .1µF to…
PICyourBrain
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41
votes
6 answers
How to reduce DC voltage using resistors?
How would one go about using a 12 V DC power source to power something which needs 4.5 V DC using resistors? Is there a way to determine how much adding a resistor would drop the voltage?
John
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41
votes
2 answers
Why would one still use normal EEPROM instead of flash?
Is there any reason why people are still using (and implementing in new systems) normal EEPROMs instead of flash memory, nowadays?
From the Flash memory wikipedia:
Flash memory was developed from EEPROM (electrically erasable programmable…
user17592
41
votes
3 answers
Why does this LED bulb have an energy efficiency rating of 'F'?
In my home, I have some halogen spot lights, which have an energy efficiency rating of 'C':
I would like to replace them with more efficient LED bulbs, but looking on the Philips website, they claim their bulbs are rated 'F'!
LEDspot VLE GU5.3 MR16…
Rocketmagnet
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41
votes
3 answers
Why is the number 63 popular in electronics?
Capacitors have a voltage of 63V (not 60 or 65).
Fuses have a value of 63A (not 60 or 65).
And there exist more odd values in electronics...
Who knows the history of this convention?
Jan van der Zanden
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41
votes
4 answers
Why does the CAN bus use a 120 ohm resistor as the terminating resistor and not any other value?
I know the reasons for using terminating resistors on a CAN bus and how important it is.
But why 120 ohm? How did this value come up? Is there any specific reason to use 120 ohm?
Swanand
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41
votes
9 answers
How to read the text printed on top of every IC?
I find very difficult to read part numbers. I haven't figured out how which kind the ideal amount of light and inclination would help me.
I also wonder why chipmakers don't paint the numbers in white for a better contrast.
Jader Dias
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41
votes
3 answers
What are the differences between NAND and NOR flash?
What are the differences and where would you use each?
JeffV
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41
votes
9 answers
Why is wired Ethernet losing its speed advantage over wireless?
This has been bugging me for a while now. I did a couple wireless transmission courses back in my university days and it's a known fact that wireless transmission is hard. Partly because it's a shared channel, physical objects can be in the way, air…
Francois
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41
votes
3 answers
Why do IR remotes influence AM radios?
When I put my IR remote near any AM radio and push any button on the remote, I can hear a sound from the radio speaker (like beeping). This phenomenon is very weird for me because the radio has no IR receiver inside.
On the other hand, the frequency…
M.A.K
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41
votes
5 answers
FPGA's vs Microcontrollers
I've worked on the Arduino family (specifically the Sanguino), built a few simple devices and a simple phototrope. I am thus pretty comfortable with microcontrollers - specifically Atmel's. I'm curious to know how do FPGA's differ from standard…
Sushrut J Mair
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41
votes
6 answers
Why does my circuit work on a breadboard, but not on a perfboard? I am new to soldering
I'm a total beginner when it comes to soldering, and recently I've been trying (and failing) to solder together a simple circuit I put together for a Raspberry Pi sensor.
Although it works fine on the breadboard, when I solder it onto one of my…
Sebastian Villate
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41
votes
1 answer
KiCAD 5 --- what is the significance of the various GND symbols?
I'm new to KiCAD. I see symbols for GND, GNDA (analog), GNDD (digital), GNDPWR, GNDREF, etc.
Is there any significance aside from "schematic documentation"?
I was expecting that maybe the reason for the multiple symbols is that the PCB layout tool…
Cal-linux
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