Using a 12 Volt Potentiometer in Your Home Projects

If you are exploring the field of do-it-yourself projects involving variable elements like light or sound modulation, a potentiometer is usually a necessary component. Now, exactly what is a potentiometer and how does it work?

At its core, a potentiometer is a specialized resistor that changes its resistance depending on the movement of a slider or knob. Usually having three terminals, two of which are fixed, the third terminal is connected to the knob, allowing the user to control the voltage passing through the potentiometer.

Examining some typical uses for potentiometers is a good way to understand how they work. One common application is as a volume regulator in audio systems. The resistance can be raised or lowered by turning the volume knob, which affects the volume of the sound coming out.

Aside from audio control, potentiometers are also used to make light dimmers, speed regulators, angle sensors, and a variety of other input mechanisms.

Using a potentiometer to change LED blinking speed without changing any circuit components or programming is an interesting way to introduce students to their use. The SparkFun Inventor’s Kit v4.0’s circuit 1B can be used to conduct this experiment.

Potentiometers come in a variety of sizes and shapes, but they always have three connection points or terminals and a moveable part (the knob) that controls the resistance between the middle terminal and either of the external terminals.

The maximum resistance of the potentiometer is indicated by the two external terminals’ fixed resistance value. The knob-connected middle terminal is essential for adjusting the actual resistance. The resistance between the middle terminal and the external terminal changes as the knob is rotated, varying between zero and the maximum resistance and affecting the circuit output, much like changing the brightness of an LED.

The outer two terminals are connected internally by a single resistor. The middle terminal is fastened to a wiper that crosses the resistor. The wiper’s movement divides 12 volt potentiometer the resistor into two sections, adjusting the power ratio between each side and modulating the resistor output.

In the case of using a potentiometer to blink an LED, for example, depending on the knob position, the potentiometer can produce an output ranging from 0V to 5V if it has a maximum power capacity of 5V. The potentiometer can output 0V when fully to the left, 5V when fully to the right, and 2.5V when in the center position by rotating the knob. The allowed voltage changes proportionally with each small adjustment of the knob.