Custom 12v HDD and power Lights for PCs - Part 3
Finished the circuit redesign, not too many changes mainly just added a second opti-coupler to make the motherboards happy. Only problem now is that I have to solder 4 to cover all the PC LEDs
|Connection from MB to Arduino|
This may look overcomplicated, and may well be, just to light some LEDs. So here is the thought process...
- Need to connect to motherboard LED lines, which expect an LED. After prototyping I am using an opti-coupler - which is an LED :)
- Need to drive the case LED and the Arduino input, which are powered from different power supplies.
- Case from MB power supply
- Arduino powered by separate 12v power supply.
- Use transistors to drive case LED , 2 are required to invert the output from the opti-coupler - i.e. NOT gate.
- Use a second opti-coupler to connect the circuit to the Arduino