Electronic Project: Build a LED dimmer with a potentiometer

Mar 20, 2021

A beginner electronics project: build a LED dimmer on a breadboard using a potentiometer, an LED, and a 9V battery, then turn the knob to change brightness.

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In this post I will show you how to build a LED dimmer with a potentiometer.

You need 4 things: a potentiometer, like this 10kΩ one:

Black 10kΩ potentiometer with three metal pins on a wooden surface

A 5mm LED, any color you like:

Blue 5mm LED with two metal legs on a wooden surface

A breadboard, where we put our components on:

White breadboard with numbered holes and red and blue power rails

And a battery. I use a 9V battery:

9V battery with green label and metal snap connectors

Plus some wires.

Start by putting the potentiometer on the board, in any place you want, with the 2 input pins on one side of the board, and 1 output pin on the other side:

Potentiometer placed on breadboard with pins inserted into holes

Press it down to connect it to the breadboard:

Potentiometer pressed down and secured on breadboard

Now connect the - pin to the blue line of the breadboard which we’ll connect to the negative pole of the battery, and the + pin to red line which we’ll later connect to the + pole of the 9V battery.

I use for convention a black wire for the - (GND) and a red wire for the positive +.

Red and black wires connected to potentiometer on breadboard

Top view of potentiometer with red and black wires connected to breadboard power rails

Make sure the potentiometer is completely turned to the left, counterclockwise.

Now connect a LED to the output pin, put the longest wire of the LED, the anode, on the same row. Then connect the cathode, the shortest wire, to the - blue line of the breadboard:

Red LED connected to potentiometer circuit on breadboard with wires Complete LED dimmer circuit on breadboard showing potentiometer, LED, and wire connections

Great, now connect a 9V battery and you’ll see the LED still turned OFF (assuming you turned the potentiometer all the way to the left, counterclockwise, which acts as a 10kΩ resistance in the example).

Be careful not to turn the potentiometer all the way to the right, or the LED could be damaged as the current will be too much to handle.

Rotate it slightly to the right and you’ll start see the light turning on, more and more intense as you turn the resistance down.

LED dimmer circuit with glowing red LED showing the potentiometer effect

Tagged: Arduino · All topics

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