Tuesday, 15 March 2011

Encoder Power Modification

The encoder relay power PCB's arrived this morning.

(great new service from Spirit Circuits, check their ebay web site out, £39 for 1 sqft of double sided PCB!)

I have been experiencing issues with encoders intermittently failing to power up, I thought this was probably due to the initial noisy power spike upon switch on, and so decided to run the encoder/SID power through a 12v relay that is switched from the 12v DC-DC on the VIC-E daughter board, this gives the 24V to stabilise as the DC-DC takes 100ms or so to power up.

Having fitted the PCB, to my dismay I was no having problems with the PIC not booting up! after spending an evening scratching my head and probing with the scope I realised it was due to an additional 220uF cap I added to the relay PCB across the 12V DC-DC supply which was causing the DC-DC to fail upon its first power up attempt causing a false start. removing the cap sorted the issue.