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How to Wire a Potentiometer for Plus or Minus DC Power Control

A potentiometer is an electronic device that provides an electrical resistance you can vary by turning a knob. Inside the potentiometer, or variable resistor, a metal wiper slides across a flat, resistive element. The resistance picked up by the wiper is somewhere between the two extremes of zero resistance and the full resistance of the element. The smooth variability of the potentiometer makes it a good choice for an electronic control, such as a volume control on a radio. Correctly wired to a voltage source, it also acts as a direct current (DC) power control, producing a variable positive or negative voltage, depending on its setting.

Things You'll Need

3 - 6-inch pieces of 22-gauge wire
50K-ohm potentiometer
15 watt to 30 watt soldering iron
Electronics solder
Bipolar DC power supply
Multimeter

Instructions

- 1
  Solder one end of a 6-inch piece of wire to the potentiometer's wiper solder lug. This is the lug in the middle. Solder one end of a second wire to one of the two end lugs. Solder one end of the third wire to the remaining lug.
- 2
  Connect the free end of one of the end lug wires to the negative terminal of the bipolar DC power supply. Connect the other end lug wire to the positive terminal.
- 3
  Turn the multimeter on. Set its selector knob to DC volts. Clip its positive probe tip to the free end of the potentiometer's wiper lug wire. Clip the negative probe tip to the power supply's ground terminal.
- 4
  Turn the power supply on. Set its voltage to about 10 volts. Rotate the potentiometer's control shaft with your fingers. Observe the voltage on the multimeter display. It should vary continuously between approximately +10 and -10 volts. Midway, you should see zero volts.

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