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Resistor gets really hot? Answered

I'm trying to build a simple circuit.

6V ---> potentiometer ---> Small DC Motor (dont know the specs)

First the potentiometer was getting hot a some smoke came out of it (its still working anyway). I thought this was happening because with 0 resistance on the potentiometer alot of current was flowing by. I added some resistors (not knowing exactly what value to add, i tried a few).
First 2k Ohms, motor didnt spin, 1k same thing, 800, 100, and finally around 5ohms. Now the motor spins and seems to be hanging on a bit better. However the 5ohm resistor is getting hot really fast....

What should I do to avoid draining the battery so fast, and keep the motor running for as long as possible (without burning resistors or the dc motor itself)

4 Replies

VygerBest Answer (author)2011-03-30

If you want to stick with using the resisters you can wire several of them together in parallel that way they will split the current up between them. They should all be the same so they will split the current equally.

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mwalling (author)2011-12-12

Drop the voltage
What is the motor rated for 3 v

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orksecurity (author)2011-03-30

If the resistor is getting too hot, you're putting more current through it than it's designed for.

But generally, potentiometers are the Wrong Way to control motor speed; they work by wasting energy (as heat). Use a real motor control circuit instead.

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7654321 (author)orksecurity2011-03-30

+1, I'm not an expert but I think PWM is the way to go

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