LED PWM Dimmer – Daniel Nebert

This was something I had created a while back, but because I was using it to develop another project, I decided to make a post about it. It is a simple PWM dimmer circuit that uses an Arduino Nano to read a potentiometer and PWM to drive a N-channel MOSFET.

Here is the circuit:

The unconnected wire coming from the Nano’s TX pin was added for a future project.

Super simple circuit here. There is a four position terminal block for input and output. The Nano’s VIN pin can take anywhere from 7V to 12V. The input voltage is fed back out to the LED. And the MOSFET is connected by PWM for low-side switching.

Here is a photo of the top side:

And a photo of the bottom:

Trying to use up some of the smaller protoboards, I used insulated wires and jammed it all in there closely.

Now, when I first built this board, I had a 76mm LED Ring Light from Adafruit (https://www.adafruit.com/product/4433), which worked. But now I was using this board to test UART for something new I am working on, so I didn’t need such a bright light. Plus if something went wrong, I didn’t want to risk the light, so I used a cheap LED and 200 ohm resistor:

Added a 200 ohm resistor to the LED cathode.

LEDs anode going to VCC and cathode going to the MOSFET’s drain pin.

Here is a video I shot of the board in action. Sorry, the screen is so far away, you’ll have a hard time seeing plot trace.

Please check out my recent posts to the right and thanks for following along!

Author: Daniel Nebert