This build uses the Adafruit Screw Shield as the basis for a PWM High Powered LED controller.PWM is implemented using six N Channel Power MOSFETSA real time clock module is integrated to initiate day and night light cycles.
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.
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.