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.
The front and back of a potentiometer, along with some added labels.
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 front and back of a potentiometer, along with some added labels.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.