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1500 questions
25
votes
8 answers
Is there such a thing as a switch that can be actuated automatically?
I'm interested in a toggle switch that can be toggled without user input. That is, the physical state can be toggled electrically. It would need to incorporate some sort of motor or magnetic actuator. My google-fu is weak in this area, and I haven't…
Mark
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25
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5 answers
Why don't relays incorporate flyback diodes?
Warning: this may be an extremely naive question (if so, please enlighten me).
Many applications of relays require a flyback diode to protect against inductive voltage. I'm unable to find any relay that incorporates a flyback diode.
Since it's such…
dss539
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24
votes
4 answers
What is the difference between a transformer and a coupled inductor?
Transformers and coupled inductors seem very similar. Is there a difference in construction? Or only in use?
This question asks something similar, but the answers don't address my question:
Coupled inductor vs an actual transformer?
Stephen Collings
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24
votes
5 answers
What is the purpose of the pin and hole on some pairs of tweezers?
I use a set of tweezers as part of my toolkit, and they have a hole in one arm and a corresponding spike in the other. Why?
user32885
24
votes
3 answers
How to limit inrush current?
I'm designing a device powered from USB. The device uses FTDI FT2232 chip for USB connection. Upon a command from a computer FT2232 chip should enable power via a MOSFET switch to rest of the circuit. This additional circuit has a capacitance of…
ibiza
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24
votes
6 answers
How do ceiling fan controllers work?
There are some devices that look like ordinary light dimmers, but are sold expressly for ceiling fan speed control. For example: Lutron Diva Quiet 3-speed control. Unlike an ordinary dimmer, this has a three-position switch for low, medium, and high…
Phil Frost
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24
votes
4 answers
Why do power companies never bother residential customers about power factors?
I recently bought a Kill-a-Watt meter to measure power consumption of my devices. This was just a fun project for me. I put this on my Mac-Mini to see power consumption during various usage states - idle, MATLAB bench mark, starting an application,…
Lord Loh.
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24
votes
4 answers
How diodes protect H-bridge DC motor driver?
I don't really understand how these diodes in this circuit and similar circuits (like driving a relay circuit) protects the controller circuit from the energy stored by the inductance of the coil.
I really appreciate if someone could graphically…
Mehrdad Kamelzadeh
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24
votes
13 answers
Level of a water tank with a microcontroller
How do i measure the level of a water tank with a microcontroller?
mad_z
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24
votes
5 answers
What is killing my MOSFETs?
This is my first post here on electronics stackexchange.
I am a hobbyits in electronics, and a professional in programming.
I am working on a inductor circuit to heat a workpiece. I have a working setup @12VAC.
In short I have the following elements…
Mike de Klerk
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24
votes
4 answers
How to calculate the power dissipation in a transistor?
Consider this simple sketch of a circuit, a current source:
I'm not sure how to calculate the power dissipation across the transistor.
I'm taking a class in electronics and have the following equation in my notes (not sure if it helps):
$$P =…
David Chouinard
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24
votes
6 answers
Why do high voltage power lines hiss when it's raining?
I noticed when walking home the other day that the high voltage (200kv I believe) lines running through here were hissing in the rain. What is causing them to hiss?
pfyon
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24
votes
1 answer
Differences between OLED, LED, LCD, and TFT Screens
I have heard about these different types of screens on DIY websites and in consumer electronics. What are the differences in these types of screens and what are their advantages and disadvantages?
Coder404
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24
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1 answer
Ferrite or iron powder? How do I tell what an unknown core is made of?
Most times when I need a small inductor, I try to find the necessary core in my junk box. Depending on what I'm trying to build (RF, power, ...), a ferrite core or an iron powder core might be the better choice.
For completeness, ...
Magnetically…
zebonaut
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24
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1 answer
Why is there a difference between pad-to-trace and trace-to-trace clearance?
I am looking to have a PCB produced for a personal project of mine. I have to use very thin traces and tight clearances to escape pads on a BGA chip on my board. I was looking at the capabilities of JLCPCB, and noticed that they differentiated…
elialm
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