Latest threads in Hobby Electronics Basicsshow only best voted threads
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Electrons and Holes (ARRL)
This is from the ARRL handbook 2010 p5.12: "When energy is added to a semiconductor lattice, generally in the form of heat, some electrons are liberated from their bonds and move freely through out...
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11 years ago
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How to bootstrap
I see the term bootstrapping, used when the designer wants a high impedance and usually low capacitance. I know it involves feedback but that's all I know. I want to learn enough to build a...
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11 years ago
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opamp voltage converter question
A simple level converter. It assumes the +4V supply can sink current, so why not just have 2 resistors between +4 and +10 and use the opamp as a buffer? +10V | | R | | |---------- | | | | R | | | | |...
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11 years ago
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Speaker resistance and sound energy
I was reading the ARRL handbook (2010) and on page 4.7 there was this sentence: "it can be said that any device that dissipates power has a definitive value of resistance" This made me think. I always...
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11 years ago
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Basic question about transistor operation
Hi everybody, could someone explain to me something very basic: the simplest transistor has 3 legs: gate, drain and source. If I were to ap ply voltage to the gate (above threshold), the transistor...
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11 years ago
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stepper construction
I'm interested in the idea of actually building a stepper and I'd like to know if anyone knows of companies selling hobbyist quantities of parts for doing that. Laminations, stators, rotors, etc. I...
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11 years ago
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current mirrors and LED matrix driving
Okay. So I've been considering current mirror design and, in particular, the idea of applying resistors on either or both of the emitters. (I'm ignoring the Wilson mirror, for now. So just the basic...
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11 years ago
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Cheap digital logic?
So, I have this algorithm. It's pretty simple. It works well on an MCU, which is fine and all, but if I could make it cheaper by using ICs instead, that'd be cool. This is mostly academic. Basically,...
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11 years ago
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Edison - Tesla Rap Video
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11 years ago
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Automobile starter lockout
Not looking for help (this time). Just wondering how simple it would be to design a logic circuit so that you car starter is disabled while the engine is running. Why haven't they don e this. Am I the...
61
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11 years ago
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61 | |
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Talema toroidal transformer
I have a toroidal transformer. It is marked: Talema TVR 2518 7702-P2S2 486 I have failed to find a data sheet using Google - anyone any ideas where I might find a data sheet? There's 8 wires: blue,...
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11 years ago
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OT: cordless screwdriver
Is anyone familiar with the cordless screwdriver in the link or a similar one? I'd like to know if using rechargeable 1.2V NiCd or NiMH cells instead of the specified 1.5V alkalines will result in a...
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11 years ago
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Help explain strange behavior of my circuit?
Hello. So, I noticed something strange with my circuit, and while I can "work-around" it, I'd like to understand what's going on. I took my LED display project to school so I could use their DC power...
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11 years ago
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*analog* brushless DC motor control?
My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. Any way it can be powered by analog, discrete circuitry? If I...
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11 years ago
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5x7 LED matrix driver
I'm considering a 5x7 LED digit module design to work with a microcontroller with these two simple ideas: (1) Constant current drive for the LEDs, settable by a single external resistor. This will set...
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11 years ago
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