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1500 questions
60
votes
9 answers
What's so great about ARM?
In a comment to this answer Kortuk asks what the ARM advantage is. I first added some arguments in my answer, but I think the question is interesting enough to be a question in itself, so that more answers are possible.
stevenvh
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59
votes
2 answers
In a USB cable, is it OK to swap the D+ and D- wires?
I heard that D+ and D- are differential signals, does it matter if I swap them when connecting a USB device to the computer?
Yan King Yin
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59
votes
5 answers
Why would one drive LEDs with a common emitter?
I've seen tutorials aimed at beginners suggest the way to drive an LED from something without enough current drive is this:
(option A)
but why not this:
(option B)
Option B seems to have some advantages over option A:
fewer components
the…
Phil Frost
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59
votes
5 answers
Why does more transistors = more processing power?
According to Wikipedia, processing power is strongly linked with Moore's law:
http://en.wikipedia.org/wiki/Moore's_law
The number of transistors that can be
placed inexpensively on an integrated
circuit has doubled approximately
every two…
Oli
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59
votes
10 answers
Why is there no `nand` instruction in modern CPUs?
Why did x86 designers (or other CPU architectures as well) decide not to include it? It is a logic gate that can be used to build other logic gates, thus it is fast as a single instruction. Rather than chaining not and and instructions (both are…
Amumu
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59
votes
6 answers
Why are digital oscilloscopes still so expensive?
I'm a beginner in hobby electronics and I am wondering
why digital oscilloscopes are still so expensive?
In times of cheap GHz CPUs, USB 3, ADSL modems, DVB-S receivers, blu-ray players which all of them have remarkable clock frequencies/sampling…
MRalwasser
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59
votes
5 answers
Can I cut an IC?
As far as I understand, the die of a DIP package is located at the center and the rest is just the lead frame. Given that I have unused pins, can I cut the top part of this microcontroller (ATmega16/32)? Will it still function afterwards?
Edit:…
v.m.
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58
votes
7 answers
What standard UART rates are there?
I know 9600, 19200, 38400, 57600, 115200 and 1.8432 Mbaud, but no others. Why are these values used, and is it simply doubling each time or is there something more complex going on (for example, 38400 quadrupled is not 115200 baud?)
The reason I…
Thomas O
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58
votes
3 answers
How important is impedance matching in audio applications?
How much will reflected signals matter in audio applications (say between an amp and a speaker, or a pre-amp and an amp)? Mostly with regards to fidelity and not power transfer.
What are the different options of matching the impedance and their…
eruditass
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58
votes
2 answers
Calculating the pulldown resistance for a given MOSFET's gate
I searched and read many similar questions, but did not find a specific answer for how to calculate the correct value for a pulldown resistor for a MOSFET's floating gate. It seems like everyone dodges the question with a 1K, 10K, or 100K "ought to…
rdivilbiss
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58
votes
2 answers
What do solid/striped lines on a wire indicate?
What do solid or dashed lines on a wire indicate? Is there a difference between the solid and dashed indicators?
Mark Harrison
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58
votes
8 answers
Can an Android tablet serve as USB Host and be charged simultaneously through a single port?
A number of Android tablets are powered through the Micro B USB port but also provide USB Host support through the same port (e.g. Motorola Xoom 2, Acer A510/700). I need to be able to use USB Host support while charging, at the full power the…
John Beatty
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58
votes
1 answer
What is the practical difference between watts and VA (volt-amps)?
I have seen one inverter rated at 300W, and another at 300VA. What is the practical difference between them, if any?
Thomas O
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58
votes
6 answers
When would I use a voltage regulator vs a voltage divider?
When would you use a voltage regulator vs a resistor voltage divider? Are there any uses for which a resistor divider is particularly bad?
Pete
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57
votes
5 answers
How can PCB trace have 50 ohm impedance regardless of length and signal frequency?
Hmm, this seems to be just another question on line impedances.
I understand that when we say "transmission line" effects we talk about things like cross talk, reflections and ringing (I guess that is just about it). These effects are not present at…
quantum231
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