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1500 questions
26
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6 answers
What 'cool' things can you build as a parent and child activity?
I would like to have a list on things a parent could build with his or her child? The things should be considered 'cool', fun and not be too advanced (the child should be able to help out and be able to understand what we are doing). A child would…
Run
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26
votes
5 answers
Can two BJT transistors work as a full bridge rectifier?
It is known that a BJT transistor looks like two diodes back to back (or head to head). With this in mind, theoretically we should be able to build a full bridge rectifier with 2 BJT transistors, one PNP and the other NPN, with the emitters…
virolino
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26
votes
3 answers
Is twisting a single ended signal with its own GND really useful?
I know that the most robust way of transferring an analog signal over long distances is via differential pairs which are twisted together and then shielded (shield grounded at one end only).
But sometimes, we have to make do with single ended…
user42875
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26
votes
4 answers
How does TI CC3000 wifi smart config work?
The ti cc3000 wifi chip has a special smart config mode, this is to allow the initial configuration of the wifi access details.
The cc3000 wiki page gives some details on how the process works,
The chip enters a smart config "listen"…
srinathhs
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26
votes
2 answers
What is the meaning behind "wire loops" in schematics?
Looking at this section of a TI PoE schematic, you can see wires looping onto themselves by MOSFETs, like Q3 and Q5 in the figure below:
What is the purpose of these wire loops near the MOSFETs?
physiii
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26
votes
1 answer
Laptop motherboard not working, quiet clicking noise
Intro how it happened:
I had cleaned my laptop from dust and reapplied the thermal paste. After this i have reassembled the device than it did not turned on. Then i took it apart connected the fan and it worked even POWER led was lit. Skipping the…
iconradez
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26
votes
5 answers
Wear leveling on a microcontroller's EEPROM
For example: The datasheet for ATtiny2313 (as do most Atmel AVR datasheets) states:
128 Bytes In-System Programmable EEPROM Endurance: 100,000 Write/Erase
Cycles
Imagine a program only requires two bytes to store some configuration, the other…
jippie
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26
votes
3 answers
Powering Arduino Nano 12volts
I know that the Arduino Nano can handle 12 volts, and it says it is recommended to power it between 7 and 12 volts. So I am wondering do I just hack together a 12 volt adapter to a Mini-B or is it possible to power it through the ICSP header?
jason
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26
votes
4 answers
What to look for in an oscilloscope?
I'm getting back into basic electronics with an Arduino after many years away from the hobby, and I've forgotten a lot of my knowledge.
One thing I'm finding is that I really need to get an oscilloscope to assist in designing filtering circuits to…
Mark Henderson
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26
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5 answers
Help with homemade electromagnet
Just for fun, I decided to build what I was hoping would be a relatively powerful electromagnet. I used this copper wire (20 AWG, entire 1 pound spool) and this soft iron core (0.5 in diameter, 6 in length). The total length of the wire is…
x7benihana
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26
votes
5 answers
Do I need to pay royalties to the SD card people if my device "just happens" to be compatible with SD cards?
I'm designing something which will use an SD card. The device will be able to read and write the cards, using publicly available specifications. Do I need to pay the SD card people?
Thomas O
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26
votes
7 answers
Is it possible to generate light with an antenna?
An antenna (e.g. a dipole) is able to radiate at a certain frequency thanks to the EM field generated by a current provided by a signal generator at such a frequency.
So, for instance:
Voltage source at frequency f (representing an amplifier) +…
Kinka-Byo
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26
votes
7 answers
How efficient is a capacitive power supply?
Something like this
Falstad sim version of it
(I'm tired, I keep making mistakes, so please excuse me for the second time.)
Now these are not very safe PSU's, due to the lack of isolation. But in sealed units, they can be a cheap way of getting the…
Thomas O
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26
votes
1 answer
How can I measure back-EMF to infer the speed of a DC motor?
I'm interested in measuring the back-EMF of a motor to determine a motor's speed because it's cheap and requires no additional mechanical parts. How can I measure the back-EMF when I'm driving the motor?
Phil Frost
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26
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4 answers
Why does radio reception consume so much energy?
On low-power radios, the current consumption for reception is similar to the consumption for transmission. For example, the Texas Instruments CC2652 System-on-Chip datasheet claims these values:
Active-Mode RX: 6.9 mA
Active-Mode TX 0 dBm: 7.3…
kfx
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