Are there any chips or simple circuits available for removing the 50/60Hz mains hum from a regular power supply unit?
So I've got a few bits of audio equipment that have bad PSUs and they have a bit of mains hum, it seems to be a common problem with cheaper audio equipment - so I'm just curious to find out about any cheap or simple solutions to this common problem.
So far I've used basic RC filters and Op Amp based ones too.