[sdiy] Simplest random source

[Seb Francis]

Hi,

I've just finished routing the PCB for my MIDI2CV and I've realised I've left off a vital part .. I need a random source for the digital random LFOs.  The PIC has built in A/D converter, so basically any noise source should allow the PIC to grab a random value.

So what I'm looking for is the absolute simplest (minimum components - PCB space is scarce) way to make a 0->5V random source.  The PIC A/D has a 120pF hold cap, so I don't think a very HF source which averages to the same voltage is suitable.

Any suggestions?

Thanks,
Seb