POTENTIOMETER ( small) and RHEOSTAT ( big )
Potentiometer is a variable resistor . It use to adjust signal and low current on electronics circuit. It has 3 terminals. If you want a variable resistor that can handle more current, you may looking for rheostat.
Potentiometer
Rheostat
We will name as terminal 1 and 2 and 3 when measure .
Step to check Potentiometer and rheostat.
1. Read the resistance value that marks on potentiometer or rheostat.
For example this potentiometer has 100K ohm resistance.
This potentiometer below has 10K ohm resistance.
2. Set the rotary switch of multimeter to resistor test function.
3. Connect the test leads to terminal 1 and 3 as shown on photo. Then read the measured value on multimeter. The measured value should be closest to the resistance value on marking.
For exsample below the potentiometer is 100K ohm and multimeter get measured value as 100K ohm so this is the good potentiometer.
4. Connect the test leads to terminal 1 and 2 as shown on photo. when adjusting the resistance by rotate potentiometer's knob the measured value should vary , you have to rotate the knob clockwise and counter-clockwise , the measured value should vary from low resistance value increase to high resistance value , from high resistance value decrease to low resistance value , depend on knob's rotation. The good potentiometer should vary its resistance when rotating . In case of it is a damage or not good one ( Bad potentiometer ) , resistance value will not vary when rotating the knob.
5. Connect the test leads to terminal 2 and 3 as shown on photo and check likewise as step 4.
Rheostat has 3 terminals as potentiometer also it has the same step to check.
Measurement between terminal 1 and 3 should get measured value as it's marking. When checking terminal 1 and 2 , terminal 2 and 3 , the resistance value must vary when you rotate the rheostat's knob.
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