Custom 12v HDD and power Lights for PCs - Part 2

Following on from my last post I prototyped the daughter board to connect each PC to an Arduino controller.  This worked fine......on the test motherboard...

Prototyping the daughter board

Prototype board for 2 channels (i.e HDD and power LEDs)

The prototype worked so I went ahead and build a second board, my work was done.  Or so I thought...

2 Daughter boards (left) - Homemade Arduino (right)

Second daughter board

I then started to test in the table, only to find that the other 2 motherboards didn't drive the LED lines in the same way ...DOH, back to the drawing board.

After some investigation with my scope and multi-meter I redesigned the daughter board.  This time I decided to use an opti-coupler on the LED lines to mitigate the problems with the first board, at the end of the day an opti-coupler is just an LED so should work on any motherboard....

Custom Arduino

I will show the new circuit design in my next post.


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