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1answer
51 views

Low voltage/current power supply for wide range of inputs

I was thinking of simple low voltage/current power supply that can accept wide range of input voltages, up to the hundreds. Let's say, the input is 20 to 160V DC and output has to be 10V with 20ma ...
2
votes
1answer
154 views

current controlled current source

Objective I am trying to build a gain-of-1 current controlled current source (current mirror) that is less sensitive to resistor value variation. The designs i have been making are highly resister ...
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2answers
202 views

Driving Relay Board with Shift Register (Shift vs Sink)

I am trying to drive some ebay bought 8 channel relay boards. They are pretty simple, have a launchpad or arduino toggle a pin and the board turns on. However, I need to use a shift register with ...
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3answers
292 views

Use transistor to auto swap power source

Basically I'm looking to use a simple transistor circuit to diconnect one V+ (or ground) when another is connected and automatically switch back when the switching source is removed. Like having a ...
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votes
3answers
330 views

Purpose of these two transistors

Hi does anybody know what's the purpose of the Q1 and Q2 transistors, sounds to me like they are constant current sources. Am I wrong? Could somebody explain me the purpose of those Q1 and Q2 ...
2
votes
1answer
216 views

Converting a battery powered pocket heater into a portable 5V power source

I bought the attached pocket heater. The elevated element seems to be heater spirals so the red cables seem to lead to short circuit - capable circuitry. Background: So I built this tight case for ...
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3answers
190 views

Capacitor discharge and 1/2 terminal voltage sources

I understand that this is really basics of electronics, but I would really appreciate if somebody clearly explained following question. So here is a small set of questions related to similar topic: ...
4
votes
1answer
202 views

Understanding a transistor configuration

I started watching this video series on a DIY lab power supply by Dave @ EEVBlog. On his video he's analyzing mostly simple constant current circuit. However, at the top of the circuit there's two ...
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2answers
288 views

Current source with pulse option

I am seeking a very fast (10nsec rise time) transistor based fixed current source that I can use with my CPU. The CPU will use the GPIO to turn on or off the current source. This will be used to ...