Quote Originally Posted by Ross77 View Post
Thanks for the replies...
Irving

So is the Pic just earthing the 5v supply to the VREF making it 0v which means there is no holding current? I presume it would then revert back when a pulse is detected on the clock line?
Well if that was the case it would be pointless IMHO. I had a quick scan round and can't find the original design writeup for this circuit. I am wondering if the PIC modulates the VREF rather than just shutting it off...