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1500 questions
85
votes
6 answers
Will radar/lidar still work when every car is equipped with them?
Self driving cars rely on cameras, radar, and lidar to recognize the environment around them. Cameras of course don't interfere with each other, since they are passive sensors. Since a signal received directly from another transmitter is much…
crj11
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85
votes
10 answers
Batteries. Why use 9V?
With all the technology available today with being able to boost voltage efficiently using SMPS, why do we still use 9V batteries? Is there some secret advantage with them that I am unaware of?
If you look at the size as well, the 9V is just big…
MCG
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85
votes
6 answers
Why does smartphone GPS find its position much faster than a GPS module?
When I'm using the arduino GPS module it usually takes a couple of minutes for it to start sending data. And it seems that it's usually the case with all GPS modules since they need to "listen" to the satellites for some time. However whenever I use…
Anthropomorphous Dodecahedron
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84
votes
5 answers
How many GPS channels make sense?
You need 4 channels to determine your position (including elevation), and I can understand that a few extra channels increase accuracy. However, there are maximum 12 satellites in view at any time, so why have receivers with more channels? I've seen…
stevenvh
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82
votes
11 answers
What's the cheapest way to link a few microcontrollers wirelessly at low speeds over short distances
What's the cheapest way to link a few microcontrollers wirelessly at low speeds over short distances.
I'm looking to keep it ultra-cheap, use common discrete parts and keep it physically small. I don't care about bands and licensing so long as it…
Toby Jaffey
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82
votes
9 answers
How does a capacitor block DC?
I am confused with this! How does a capacitor block DC?
I have seen many circuits using capacitors powered by a DC supply. So, if capacitor blocks DC, why should it be used in such circuits?
Also, the voltage rating is mentioned as a DC value on…
Arun M
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81
votes
11 answers
Why is there such a strong preference for 45 degree angles in PCB routing?
I've always wondered this: every single modern PCB is routed at 45 degree angle increments. Why does the industry prefer this so much? Doesn't any-angle routing offer more flexibility?
One plausible theory would be that the existing tools only…
Roman Starkov
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81
votes
9 answers
What exactly is voltage?
Bit of a strange question, but what is it? My physics teacher said it was kind of like a "push" that pushes electrons around the circuit. Can I have a more complex explanation? Any help is much appreciated.
imulsion
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81
votes
8 answers
Decoupling capacitors: what size and how many?
Lots of chips nowadays require smoothing capacitors between VCC and GND for proper function. Given that my projects run at all sorts of different voltage and current levels, I was wondering if anyone had any rules of thumb for a) how many and b)…
jeremy
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81
votes
7 answers
What is "forward" and "reverse" voltage when working with diodes?
What is the difference between "forward" and "reverse" voltages when working with diodes and LEDs?
I realize this question is answered elsewhere on the interwebs such as wikipedia, but I am looking for a short summary that is less of a technical…
JYelton
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80
votes
3 answers
Why are circuitboards traditionally green?
Green is the most common circuit-board color because it has become an industry standard.
What I'm interested in is How the traditional "PCB Green" become a standard in the first place?
Were there any interesting historical reasons for the initial…
Connor Wolf
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80
votes
7 answers
Using clothesline steel core wire rope for AC and DC
As I am currently in a war zone, I don't have many options for cabling.
I found this clothesline (steel core plastic wire rope) that appears to be one mm of diameter (steel core diameter.) 13 meters of it measured 7 ohms resistance.
Edit: It is 3.8…
USER249
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78
votes
3 answers
Why are they called breadboards?
Why are solderless protoboards called "breadboards"? I've used the term for decades but couldn't answer a student's question about the name.
Ellen Spertus
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77
votes
4 answers
What is ground and what does it do?
I'm a bit confused about the concept of ground, and perhaps voltage as well, particularly when trying to analyze a circuit. When I learned about Ohm's law in grade school, I learned how to apply the law to calculate current, voltage, and resistance…
hedgepig
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77
votes
13 answers
How to connect USB Connector shield?
How should I route USB Connector shield on PCB? Should it be connected to GND plane right where USB is placed, or should the shield be isolated from GND, or should it be connected to ground through ESD protection chip, high resistance resistor or…
Andrzej H
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