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1500 questions
56
votes
6 answers
Does my Arduino-based device need FCC certification?
I've built a small consumer device that contains an Arduino Nano. It's coupled to a custom daughter board that allows it to pulse a 12V electromagnet at about 1 hertz as well as inteface to some sensors. It does not intentionally produce any RF…
Cerin
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56
votes
10 answers
Why is an Ethernet cable not grounded?
There is no dedicated GND in the classical Ethernet 8P8C ("RJ45") pinout.[1]
Why does the Ethernet spec not include a ground, unlike many other cable types used for interconnecting devices that may both have its independent power source as well,…
mykhal
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56
votes
7 answers
What exactly is a current source?
What I understood from the definition of current sources is that it is a source which supplies a constant current across a load no matter how the other parameters (like resistances for example) in the circuit are changed. Am I right?
If I'm right,…
Green Noob
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56
votes
3 answers
What's this importance of datasheets?
As someone starting with electronics I keep hearing, "Check the datasheet!"
Why are datasheets so important and what information can I expect to find in them? It seems like a large amount of information would come from experience and know how, not…
stevenvh
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55
votes
5 answers
Programming microcontrollers: JTAG, SPI, USB oh my!?
I've noticed, with regards to microcontrollers, there are several way to program them. I am sorta familiar with USB as my Arduino's can be programmed via USB.
What is a JTAG or SPI interface?
Ultimately I know that these interfaces provide a means…
jdiaz
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55
votes
7 answers
What is the usage of Zero Ohm & MiliOhm Resistor?
I am new to PCB design and I noticed that some schematics use 0Ω or 100mΩ resistors. What is their purpose and why do we need to use them in our PCB design?
Normally if we wish to probe how much current the load is taking, we put a jumper pin across…
Dennis
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55
votes
5 answers
Triac versus Relay
What are the scenarios where Triacs can not replace a relay or vice-versa?
Daniel Grillo
- 7,659
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55
votes
10 answers
Amplification before tubes and transistors were invented
Telephones are older than vacuum tubes and of course transistors. How was signal amplification done?
I mean the technology, not the details.
EDIT
Some additional informations that I should have given at the beginning :
The question is…
andre314
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55
votes
6 answers
Do I really need resistors when controlling LEDs with Arduino?
I'm just trying out Arduino Uno for the first time with 2 blinking LEDs on a breadboard. All the tutorials on the Internet seem to use a resistor. I do know the function of resistors, but does it really matter here? These LEDs are working just fine…
40pro
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55
votes
11 answers
Why would clipping a wire cause a bomb to explode?
There are a lot of movies and video games that depict defusing bombs, most of which boils down to picking the right color wire. Something like this:
Now, that's a part I don't understand.
simulate this circuit – Schematic created using…
yuritsuki
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55
votes
6 answers
Maximum I2C Bus Length?
What is the maximum length of cable that could be used to connect two I2C devices (I2C master-> I2C slave)?
Yes, I know that I2C is really designed for intra-board communication. I have been tasked with a "design goal" of using a common I2C bus for…
Nate
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54
votes
8 answers
Personal electronics tool kit
What are the items you have in your personal electronics tool kit?
mad_z
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54
votes
5 answers
I don't care how a transistor works, how do I get one to work?
Every reference I can find on transistors immediately launches into theory-heavy alphabet soup. The above seems also to be assumed knowledge for reading a datasheet. I don't care; I just want to get one to work.
I understand there's some…
Robert Atkins
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54
votes
14 answers
Solid ground-plane vs hatched ground-plane
Recently while routing a PCB, I came across the option to fill/pour my ground plane with either solid or hatched copper. I've also noticed that the old Arduino Duemilanove also had a hatched ground plane.
What benefits does a hatched ground plane…
Vikram
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54
votes
7 answers
Why don't we make CPUs with 1000s of layers to make use of space in the third dimension?
I am wondering why don't we make processors such as CPUs with 1000s of stacked layers to make use of space in the third dimension now that we have three-dimensional transistors. To be clear I'm referencing making something of a rectangular-prism…
Ethan
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