What Is a Potentiometer? - dummies

# What Is a Potentiometer?

Pot is the shortened name for a potentiometer. A potentiometer (pronounced “poe-ten-shee-AH-meh-ter”) is a variable resistor. The pot enables you to vary the blink rate of the LED without changing any components in your circuit.

Pots come in various shapes, sizes, and values, but they all have the following things in common:

• They have three terminals (or connection points).
• They have a knob, screw, or slider that can be moved to vary the resistance between the middle terminal and either one of the outer terminals.
• The resistance between the two outer terminals is a fixed (constant) resistance, and it is the maximum resistance of the pot. This resistance doesn’t vary even when the knob, screw, or slider is moved.
• The resistance between the middle terminal and either one of the outer terminals varies from 0 Ω to the maximum resistance of the pot as the knob, screw, or slider is moved.

The maximum resistance (between terminals 1 and 3) of the pot — 10 kΩ — is stamped on the back of its case. If the control knob is positioned at the midpoint of its full range, the resistance between terminals 1 and 2 will be 5 kΩ and the resistance between terminals 2 and 3 will be 5 kΩ. As you turn the knob, the two variable resistances — that is, the resistance between terminals 1 and 2 and the resistance between terminals 2 and 3 — change, but their sum is always the maximum resistance of the pot.

For instance, say you turn the knob so that the resistance between terminals 1 and 2 is 2 kΩ. In this case, the resistance between terminals 2 and 3 is 8 kΩ. As you vary the resistance between terminals 1 and 2 from 0 Ω to 10 kΩ, the resistance between terminals 2 and 3 varies the opposite way — that is, from 10 kΩ to 0 Ω.