Ok, that gives me a lot to think about.
Unfortunately the protoboard has to stay (this is a one off).
I am using a plugpack, but the interference sound seems vary according to what the pic/s are doing, so I don't know what that means.
I don't think i've ever tested this particular project with a battery though,
so that might be interesting, thanks

I guess I'll revive this if I run into trouble.