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DIY Potentiometer

A potentiometer is a type of resistor that can be adjusted. The potentiometer uses a moveable electric lead called a wiper; this wiper is placed between the two fixed outside electric leads. When the wiper is adjusted to be closer to one of the fixed leads, the resistance between the fixed lead and the wiper is reduced; likewise, if the wiper is moved further away from the fixed lead, the resistance increases. You can create a simple potentiometer by using a graphite rod such as those found in mechanical pencils.

Things You'll Need

Electrical wire
Electrical pliers
3 Crimp-type ring terminals
3 Alligator clips
Screwdriver
Aluminum foil
Mechanical pencil refill lead
Digital multimeter

Instructions

- 1
  Use the pliers to cut three segments of electrical wire, with each segment being 4 inches long. Remove 1/2 inch of insulating material from the ends of each wire using the cutting edge on the pair of pliers.
- 2
  Place the first ring terminal over one end of the first wire. Crimp this ring terminal to the end of the wire. Place the second ring terminal over one end of the second wire, and crimp the second ring terminal on to the wire. Place the third ring terminal over one end of the third wire, and crimp this terminal on to the wire.
- 3
  Use the screwdriver to loosen and remove the screw from the first alligator clip. Place the ring terminal connected to the first wire over the screw, and reinstall the screw to the first alligator clip. Repeat this step for the remaining alligator clips and wires, respectively.
- 4
  Tear off a piece of aluminum foil that is 1/4 inch wide by 1/2 inch long.
- 5
  Take the piece of aluminum foil and fold it over the center of the refill lead. Attach the first alligator clip over the fold so that the clip holds the aluminum foil to the refill lead, but the clamp does not grasp the refill lead itself. This electrical connection will serve as the potentiometer wiper.
- 6
  Attach the second alligator clip to the one end of the refill lead. The metal part of the alligator clip must make contact with the refill lead.
- 7
  Attach the third alligator clip to the other end of the refill lead. The metal part of this alligator clip must make contact with the refill lead.
- 8
  Turn on the digital multimeter and set the measurement scale to ̶0;Ohms.̶1; Attach the red multimeter probe to the loose end of the first wire. Attach the black multimeter lead to the second wire. Observe the resistance reading.
- 9
  Move the first alligator clip so that the wiper moves away from the second wire. Observe the resistance reading. Since the electric current has to move through more of the resistive material, the resistance reading will go up.
- 10
  Move the first alligator clip so that the wiper moves towards the second wire, taking care that neither the first alligator clip nor the aluminum foil touches the second alligator clip. Observe the resistance reading. Since the electric current has a shorter path through the resistive material, the resistance reading will go down.
- 11
  Disconnect the red multimeter probe from the first wire and connect it to the loose end of the third wire. Observe the multimeter reading. Move the wiper from one end of the refill lead to the other. Observe that the resistance value does not change. When electric current passes from one of the end leads to the other, the potentiometer acts as a fixed-value resistor. Moving the wiper will not affect the resistance reading.

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