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1500 questions
35
votes
3 answers
Why is there a small cut in this ampere meter shunt?
I have seen lots of ampere meter shunts like this.
What is the reason for this small cut?
user_fs10
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35
votes
7 answers
Why don't we use low voltage Power Sources for high wattage applications?
Super nooby question involving Ohm's law, but this has been on mind this morning.
Say I have a 60W device, and I want to power it. Usually this calls for a 120V source or something. However, why not use a 5V source and draw 12A with really low…
Capn Jack
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35
votes
2 answers
Cross section of ceramic capacitors
I am trying to make a fault analysis of a bunch of ceramic capacitors.
Short description of the application:
10 220 µF ceramic capacitors 1210 package are placed in parallel with a 3.6 V battery. A MCU wakes up periodically (maximum once per…
Filippa
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35
votes
9 answers
What happens when an embedded program finishes?
What happens in an embedded processor when execution reaches that final return statement
Does everything just freeze as it is; power consumption etc, with one long eternal NOP in the sky? or are NOPs continuously executed, or will a processor shut…
Toby
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35
votes
4 answers
How to invert a digital signal
I need a way to invert a digital signal i.e. if the input is high, I want the output to be low and if the input is low I want the output to be high.
I think this can be accomplished with a single PNP transistor, but wanted to verify that here. …
Matt Ruwe
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35
votes
7 answers
Are there any Analog FPGAs?
As I understand it FPGAs are flexible "digital" circuits, that let you design and build and rebuild a digital circuit.
It might sound naive or silly but I was wondering if there are FPGAs or other "flexible" technologies that also make analog…
Ali
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35
votes
5 answers
What is a JTAG?
I'm pretty new to embedded systems, and I keep seeing this term used all the time, but I can't quite understand what is it. A quick search online yields this Wikipedia page: https://en.wikipedia.org/wiki/Joint_Test_Action_Group which describe it as…
UnTraDe
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35
votes
2 answers
Odd markings on flash ICs - Are these factory rejects?
I recently purchased a really, really cheap SSD ($25.99), and I popped open the case out of curiosity.
The flash chips have etched bars across the part numbers, something I've never seen before.
Is this a standard way of marking chips as…
Connor Wolf
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35
votes
2 answers
Problems with L293, L298 and SN754410 H-bridge drivers on a low voltage supply
This question is about the following three integrated H-bridge drivers: -
L293 or L293D (D = protection diodes added)
SN754410 (protection diodes included)
L298 (no protection diodes)
Time after time the same question keeps coming up - someone is…
Andy aka
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34
votes
9 answers
Bidirectional 5 V to 3.3 V level shifter
How do I interface 3.3 V Input/Output to 5 V Output/Input? I need it primarily for an Arduino Due but any general purpose bidirectional circuit (or IC) would work.
Some people advised me to use the SN74AHC125 and CD4050 ICs, but I don't understand…
3bdalla
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34
votes
5 answers
How come radio signals don't interfere with each other all the time?
I'm a newbie on wireless technologies and I'm trying to understand how they work.
One thing I don't understand is this: How come transmissions from different devices don't interfere with each other all the time?
For example, I'm living in a dense…
Ram Rachum
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34
votes
2 answers
What is the difference between an injected and regular STM32 ADC channel?
The STM32F1's reference manual describes "regular" and "injected" ADC channels but is not clear on the difference. What is the difference between the two types and when might you use one or the other?
joeforker
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34
votes
2 answers
RTL vs HDL? Whats the difference
What is the main difference between RTL and HDL? To be honest I searched / googled it yet people are divided in their opinions. I remember one saying that HDL is the computer language used to describe a digital circuit and when it is synthesizable,…
vvavepacket
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34
votes
3 answers
Why does the E12 resistor sequence use 27 and 33 instead of 26 and 32?
On the assumption that the E12 values were chosen to be equally spaced logarithmically between 10 and 100 ohms we get the ideal values of:
10.00
12.12
14.68
17.78
21.54
26.10
31.62
38.31
46.42
56.23
68.13
82.54
100.00
Therefore: the nominal value…
Dabbo
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34
votes
4 answers
Why put a 10k resistor between VUSB and GND?
I recently came across Yet Another RP2040 Trinket (the Beetle RP2040.) In their linked schematic something caught my attention:
It is R10 below - a 10k resistor straight between VUSB and GND. I can't come up with a reason why you'd want it to be…
tylerl
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