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1500 questions
36
votes
5 answers
What makes a pull-up/down resistor strong or weak?
A "strong" pull (up/down) resistor would be one of a relatively low value, while a "weak" one would be of a relatively high value.
For example, a pull-down resistor would be used to keep an I/O pin low, but a button connected from that pin to VCC…
JYelton
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36
votes
4 answers
Headphone wire color coding
How do I tell which wire is which if I have a copper wire, red and green coded wire? Is the unshielded copper wire ground?
stanigator
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36
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1 answer
What is XBee and how is it different from Zigbee?
It's easy to get an introductory explanation of Zigbee.
Zigbee on Wikipedia
Home networking with Zigbee
Zigbee alliance
But technical information on XBee seems harder to find. It's unclear to me what its similarities and differences to Zigbee are.
Craig McQueen
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36
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11 answers
What causes a fuse to blow, the current or the power?
Fuses and circuit breakers are often specified at a certain current they will 'blow'.
Increasing the current will also increase the power.
So if a fuse is rated for 12V DC and 20 A, this would be equal to 240 watts. If a different voltage is…
Jackson Harvey
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36
votes
9 answers
Why is the Digital 0 not 0V in computer systems?
I'm taking a computer system design course and my professor told us that in digital systems, the conventional voltages used to denote a digital 0 and a digital 1 have changed over the years.
Apparently, back in the 80s, 5 V was used as a 'high' and…
Anirudh Ajith
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36
votes
3 answers
General "rule of thumb" for unused IC pins
This is somewhat similar to this question about NC pins. In cases where the datasheet doesn't specify what to do with unused IC pins, what is the recommendation to do with these pins? In particular I'm thinking of GPIO pins for the AT32UC3C…
helloworld922
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36
votes
8 answers
Why do devices stop operating properly in extreme cold?
I have noticed that a lot of smart phones say that they won't operate under -4 degrees F (-20 degrees C). Can anyone explain to me what happens when the phones get cold that stops them from operating?
Sean Moriarty
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36
votes
5 answers
How did people realize they could do logic with electronics?
How did people realize they could do logic with electronics? Are there anecdotes or records of the first realizations? I'm wondering about the first "eureka" moments.
Kinnard Hockenhull
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36
votes
2 answers
Why are SMD LEDs shipped in a sealed bag containing desiccant?
I had a selection of 0805 LEDs in my last Mouser order and was a bit surprised to discover they arrived in heat-sealed (rather than folded and taped with sticker) bags containing a desiccant bag and some sort of litmus-esque paper indicator saying…
scanny
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36
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8 answers
Are two (or N) resistors in series more precise than one big resistor?
Let's say I have one 2 kΩ resistor with 5% tolerance. If I replace it with two 1 kΩ resistors with 5% tolerance, will resulting tolerance go up, down, or remain unchanged?
I'm bad with probabilities, and I'm not sure what exactly tolerance…
Amomum
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36
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5 answers
What exactly does ARM sell to vendors?
Assumptions:
Computer architecture: Describes how the different modules of a processor interact with each other.
A computer architecture is defined using vhdl files
Computer Organization: Describes the physical layout of the processor modules on…
aiao
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36
votes
7 answers
Comparison Between SPICE Simulators
I've recently realized that I can't do everything easily in ngspice, mainly because analysis has to be performed through the interpreter. I'm considering switching to a new SPICE simulator.
I'd like a list the advantages and disadvantages of the…
sj755
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36
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4 answers
Why do characteristic impedances matter only when traces are longer than half a wavelength?
Why are characteristic impedances of traces not considered when the traces are shorter than half a wavelength? I've had the same issue with light diffraction, which happens when pinholes are smaller than half a wavelength - it sort of makes sense…
user42875
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36
votes
6 answers
How do digital oscilloscopes achieve such high sample rates?
From the perspective of data capture, how is this achieved? If I wanted to implement a home-made digital device to capture high frequency analogue signals, what are my options? So far, I've only come up with some fairly useless ideas for…
Jodes
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36
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5 answers
Why do microwave ovens, with metal walls, not blow up?
Why does a microwave oven with metal (?) walls work fine, but if I (theoretically) put a metal spoon in it, "bad things" may happen?
Maybe these internal walls are not conductive?
Kamil
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