Potentiometer

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cmcimino

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Hey I am building a bubble machine for a project and I can only use 6V max for power. I need to be able to control the speed of one of my motors. Should I use a potentiometer? I have one but I can't get it to work. The motors are 1.5V-3V and being powered 2 AA batteries each. I tried wiring a potentiometer in between the batteries and motor but I cant get it to work properly. The potentiometer is a 100k Ohm Linear Taper Potentiometer, 250VDC .25W. I don't really know what I'm doing with so help would be very appreciated.
 
You need a much lower value pot. Try a 10Ω or a 100Ω pot. Wire only to wiper and one end.
 
OK where can I get that? I got my last one at Radio Shack but I dont think they had any low Ohm pots.
 
And of course a more efficient way would be PWM.

Problem with a potentiometer is power wasted and heat. If you decide to use a potentiometer, please consider a power resistor in series with the pot and motor of a low enough value as to not deter from the circuit but to current limit the motor. It's a small motor but .25 watts isn't much for your pot and it might get very hot otherwise.

Look into PMW, it is way more efficient and friendlier to your components.
 
Batteries produce DC.
You were told to Google a DC motor speed controller that will explain Pulse-Width-Modulation (PWM).
 
Should do.
Put it in series.
Use only the middle and one end, as has been said.

Lets us know how it goes.

John
 
Yea everything works. I bought a 25 ohm rheostat from radioshack and I am able to control the speed of my motor. Thanks a lot guys!!
 
cmcimino said:
Yea everything works. I bought a 25 ohm rheostat from radioshack and I am able to control the speed of my motor. Thanks a lot guys!!
Click to expand...

Good deal.

I hope you will continue to study in order to understand why it worked... don't be content with this one success, but go to the next level and be able to forsee a result before the attempt.

Added: Also thanks for coming back to let us know your progress. Often, we never know the end result of someone's problem.
 
Last edited:
Frequently when somebody connects a potentiometer in series with a DC motor to control its speed simply reduces its torque so it cannot start running.
 
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