Probably the Simplest Way to Control Brightness of Desk Lamp!

I bought this gorgeous desk lamp for my room and added two warm LED lights to create beautiful light. But it had one major issue: there was no option to control the brightness, and the default brightness was too high to create a good ambiance!

Thus, I came up with a straightforward idea, and it took only 20 minutes to complete the whole project!

Warning: Ensure the power cord is disconnected from the outlet while working with high voltage.

List of items needed:

1 x 100k variable potentiometer LINK

1 x Potentiometer cap LINK

2 x low-wattage LED lights LINK

Soldering iron and drilling machine.

The circuit is very straightforward; I need to add a potentiometer in series with the LED. You may argue why I did not use a PWM controller, Well it adds ripple to the output light and the PWM circuits are usually large enough to fit on a small desk lamp. Moreover, they are commonly used for high wattage applications.

The potentiometer is a variable resistor whose resistance changes based on the turning of the knob. Thus the brightness control is very smooth.

At high resistance, the brightness of the light is low

At low resistance, the brightness of the light is high

Since I am using low-wattage light, this simple setup with a 6-pin potentiometer is enough to handle the load.

The first thing we need to do is place the potentiometer properly. I used a 0.25-inch drill bit to make a hole in the metal body.

Then placed the resistor and fastened it with a nut.

Cut the wire connected to the lights. Take the live wire(red) and connect it to the middle pin of the potentiometer. Connect the led wires as shown in the diagram. Add proper isolation. I used some scotch tape and glue to add isolation.

This simple circuit only works with a low-wattage LED light, not filament. LED lights are highly efficient and consume very little power. Filament light consumes a lot of power and can burn the potentiometer!

If you want to use a filament, consider using a PWM brightness controller. LINK

The light works perfectly with no heat issue. I prefer this over the PWM controller since it adds no ripple to the light. The control is also very smooth!

Please only try to recreate this if you have good knowledge about practical electronics. Working with mains voltage can be dangerous.

I glued all the connections using a hot glue gun for further protection. This completely insulates the wires.

Also, if you are using a metal lamp, then please make sure to connect its body to the ground, as shown in the picture.