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Have a few 5v DC motors with variable resistors attached to provide positional data. I want to hook this up to my Arduino to try and figure out the rotation of the motor, but someone told me I'd have to connect a 220 ohm resistors and a  1.0 uF capacitor.

Can anyone tell me why a capacitor would be necessary for this? Do I really need that?
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Variable resistors? Like the shaft of the motor drives the shaft of the resistor?
Is it a 3-lead variable resistor?
If you put a meter on the resistor between the middle lead and one leg, what resistances do you see as it rotates?
If is a 3-lead device, you can connect 1 leg to +5, one leg to Gnd, and the middle leg to an arduino analog input.  The resistance from outer leg to outer leg is important - if too low, say under 1K, you will have to check the power rating on the part, make sure you won't burn it out.
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It's a three lead resistor, operating at 5v I think. But yes, the shaft of the motor turns the resistor.

So are you saying the capacitor might be needed so that the voltage doesn't drop too low between the two outer legs?
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No, cap would be added from wiper to Gnd to smooth out the level some as it changes.
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Sorry, I'm still new to this, so I want to be totally clear.

The resistor would connect to the +5v pin of the VR? And the middle pin of the VR would connect to the capacitor and then go into the analog input of the Arduino board?
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Like this


* VariableResistor.jpg (79.1 KB, 960x720 - viewed 31 times.)
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Great! Thanks so much for you help.
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Glad to help.
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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