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1500 questions
21
votes
7 answers
What are the smallest microcontrollers?
I am looking for a microcontroller to use in a project which is very space-limited. What microcontrollers have some of the smallest packages? This does not need to be high performance, most microcontrollers are more powerful than is necessary in…
Alex I
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21
votes
3 answers
Is it OK to solder a power cord?
A few people have advised me to never solder a power cord directly to a PCB, but they couldn't explain why not. Why can/can't I solder it directly?
pebbles
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21
votes
5 answers
What can reduce overshoot and ringing on a simple square wave pulse generator?
I've built a simple RC and Schmitt-trigger-based square wave pulse generator. On the breadboard, it has some obvious unwanted qualities due to jumper length, the breadboard itself, etc.
Schematic and breadboard version:
And the waveform…
JYelton
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21
votes
3 answers
What are the ways to make a dual power supply from a single voltage source?
I have a function generator IC XR2206 from EXAR. It's application circuits uses dual power supply +/-9 volts. How can I make such a 9-0-9 dual supply from a single voltage source like a battery or an adapter?
C--
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21
votes
2 answers
What is the meaning of "half bit" in this context?
In RS-232 specification, the stop bits can be 1, 1.5 or 2 stop bits...I wonder how it's possible to have half a bit?
Also some ADC math uses 0.5bit precision in the IC specifications/datasheet. Can someone elaborate in this subject?
mFeinstein
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21
votes
6 answers
What is the correct command sequence for microSD card initialization in SPI?
I am trying to interface a microSD card (2 GB, Kingston, Sandisk) with a Silicon Labs C8051F931 controller.
I am very much confused about the sequence which I have to follow for initialization. In the book SD Card Projects Using the PIC…
gpuguy
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21
votes
3 answers
Does adding thermal relief on PCB increase electrical resistance?
I am just getting started on PCB design (for fun) and came across this term called thermal relief. It increases thermal resistance so the components can be soldered easily. But according to what I have learned, thermal and electrical resistance are…
user2578666
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21
votes
2 answers
What is the "+:" operator called in Verilog?
I am going through a Verilog test case, and I found this statement:
assign XYZ = PQR_AR[44*8 +: 64];
What is the "+:" operator known as? I tried to find this on google, but I didn't get any relevant answer.
shailendra
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21
votes
2 answers
What's an alternate pin function on a microcontroller?
I'd like to know what "Alternative Function" refers to in the context of the IO ports of a microcontroller.
I don't need to know how to activate it when connecting to a peripherial, but I'd like to know what it exactly is and why we'd need it.
user929404
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21
votes
3 answers
How to water-protect my Arduino?
I am building a watering system with an Arduino. Basically it runs on a track with a hose that drips water down on plants a couple of times every day. Its outside, and water might sometimes get from the leaves of the plants down to the Arduino…
bogen
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21
votes
10 answers
Is there ever any reason to prefer 5% tolerance resistors over 1%?
I work at an electronics store and the other day a customer came in who was rebuilding a circuit board. I sold him some resistors, but later he came back in wanting to return some of them because they were only 1% tolerance, and he needed 5%. I'm…
Justin Pederson
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21
votes
8 answers
Fans: suck or blow?
For a fan, should air be sucked in, or should it blow air out?
I'm talking about an enclosure mounted fan.
Thomas O
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21
votes
4 answers
How do large electrical grids stay in phase?
I am a math student with some background in physics so apologies if the question is naive - but I'm trying to understand how large electrical grids like the Eastern Interconnection maintain locally a consistent phase, when it seems like the grid…
Dominic Wynter
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- 5
21
votes
7 answers
Where to leave the test leads on a Fluke multimeter
I think this is somewhat of a "trade secret".
Being a software engineer for embedded devices myself, I often find myself using oscilloscopes and multimeters. I have always wondered about my Fluke 87-V and all flukes before that.
They have these…
Stijn
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21
votes
2 answers
Why do travel transformers have a setting for either 50W or 1600W?
I've noticed this "feature" on a number of travel-oriented voltage converters - they either are meant to be used for small 50W loads, OR for larger loads up to 1600W. But you can't run a small load on the higher setting.
Here's an example of one…
StayOnTarget
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