This project uses IRLB8721PbF MOSFETS. These particular devices are good for the Arduino because the base current required to fully open the gate is less than 5v.

I chose to use a power supply case to house this project. The built in fan will supply plenty of airflow over the heatsinks attached to the MOSFET’s.

This design is intended to provide power and dimming to 24 5 watt LED’s distributed over 6 channels.

In this case power is 12 volts. I expect the MOSFET’s to sink about 5 amps per channel.

I am including a push button and a LED that will be used for basic I-O. The number of pushes on the button tell the arduino which lighting program to run. The LED flashes sequences to indicate the program that has ben selected or is running.

The program that I have written includes selectable day, night, and 24 hour modes.

Project Steps

Prepare your case.

Take off the over of the ATX Power Supply and clip off all of the wires at board level. Save these wires they will be useful later

NOTE: THE FOLLOWING STEPS COULD BE CONSIDERED DANGEROUS. The power supply circuit board has lots of capacitors. They may be charged. You could be seriously electrocuted if you touch one. PLEASE STOP IMMEDIATELY IF YOU CANNOT SAFELY PERFORM THE FOLLOWING TASKS

Unscrew and remove the circuit board. Dispose of the board safely remembering the shock hazard.

You now have a fan cooled project case.

Make your test circuit.


Also have a few other scraps of 22 and 18awg wire handy for building wiring harnesses etc...