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1500 questions
48
votes
5 answers
Why are things like RESET/MCLR active low on most ICs?
Convention?
Easier to implement?
Another reason?
Is there a reason things like MCLR or RESET on microcontrollers are active-low, that is, you have to pull them down to reset the IC, and pull them up to "run" the IC.
I'm just curious because this…
Thomas O
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48
votes
3 answers
Why do we connect a battery to ground when jumping a car?
This may seem like a very simple question, but I've searched all over the place and haven't found an answer.
When jumping a car, we connect the + end of the charged battery to the + end of the dead battery, and the - end of the charged battery to…
Ken Levinski
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48
votes
2 answers
What is input and output impedance of an opamp?
I have never understood input and output impedances of an op-amp. If anyone can explain what these two terms mean in an op-amp I'd highly appreciate it. Thank you!
http://www.eecs.tufts.edu/~dsculley/tutorial/opamps/opamps5.html
user734861
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48
votes
2 answers
Why don't electrons take the shorter path in coils?
Below is a copper coil, presumably forming an electromagnet. From my understanding the electrons travel around the coil to produce a magnetic field. But why don't the electrons jump the wires and take the shortest path?
Below I tried to draw the…
rrswa
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48
votes
8 answers
Why are NAND gates used to make AND gates in computers?
Why is this a standard for AND gates
when it could be made with two FETs and a resistor instead?
minseong
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48
votes
2 answers
What is wrong with my 50 Ω grounded coplanar waveguide?
I've been working on a 4-layer design built around the EFR32BG13 Bluetooth Low Energy SoC. While trying to measure the impedance of the antenna to build a matching circuit, I discovered that my short grounded coplanar waveguide (GCPW) transmission…
Michael Cooper
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48
votes
5 answers
CMSIS vs HAL vs Standard Peripherals Library
So I'm switching from PICs to ARM and I bought an STM32F4 discovery board.
So far I understand that to program it you can either access all registers directly in memory (obvious way) and also there are 3 main libraries you can use to make your life…
John
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48
votes
11 answers
Software for workshop - electronic components stock management
Im looking for reliable software that will help me to manage electronic components, tools, drills, wires in my workshop.
Currently I have probably more than 1000 diffrent components. My brain can't manage this anymore.
My "wishlist":
preferable…
Kamil
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48
votes
7 answers
Why aren't headphone jack shaped plugs used for data?
With Apple's lightning cable, and USB 3.0, reversible cables are taking off, and I personally think this is very convenient. But we have had better than reversible for a long time, in the form of the headphone jack, which can be inserted in any…
Drew
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47
votes
8 answers
Can we build capacitors on a PCB board?
For the magnitude of nF or µF capacitors, I hope I can build them on a PCB board. The capacitor is like a two metal layer and something between them.
Is this possible?
Not buying the capacitor, just design the capacitor on the PCB board. Double…
alan
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47
votes
5 answers
Is Bluetooth Communication Possible Without Pairing?
I am working on a device which can wirelessly activate a system "instantly". The first thing which came to mind was to use RFID technology which has the advantage of instant and cheap communication. However, I am interested in using my phone's…
capcom
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47
votes
5 answers
Microcontroller shelf life
Our purchasing department requested the AT32UC3B1256 and the supplier has a few thousand in storage. However, those trays have a date code from 2009.
While shelf life is normally not much of an issue with integrated circuits, 10 years is quite a…
Rev
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47
votes
9 answers
Vias directly on SMD pads?
I was looking at an example board schematic provided by TI and I noticed something rather curious: vias were placed directly on SMD pads.
Is this a normal/acceptable practice to follow, or is it recommended/better to put a short trace and then have…
helloworld922
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47
votes
4 answers
Why don't we use wireless electricity today?
I was reading about Nikola Tesla today (via the Oatmeal) and read about the Wardenclyffe Tower which (among other things) was intended to transmit electricity wirelessly. Forgive the naivety of the question, but if technology that could transmit…
n00b
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47
votes
8 answers
How to choose a MCU platform?
There are numerous MCU platforms and once somebody has gotten used to one, they are generally reluctant to switch to another platform.
My question is: If one started using a MCU for general purpose tasks today, how would one go about choosing one?…
ARF
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