DIY power supply question.

[haveyouseenhim]

When making a multi output isolated regulated power supply, does it have to have separate transformers and rectifiers? Or can I use one transformer and multiple rectifiers? Or one transformer and one rectifier?

What are the pros/cons of each configuration?
I did a bit of searching and I get varying answers.

[psychedelicfish]

The idea of isolated power supplies is to keep the grounds of each supply separate, so you don't get ground loops from pedal to pedal. I think that separate transformers would be best.

One thing I was thinking of doing is designing a circuit to give multiple, isolated outputs from one power supply. I was thinking of having a bridge rectifier input, so it can accept an AC power supply as well, lots of filtering, then some switching to give a high frequency square wave to a series of transformers (which wouldn't need to be large because of the frequency) and some rectification and regulation (as well as feedback to alter the pulse width of the switching circuit) to give multiple isolated, stable voltages for my pedals.

[PRR]

Isolated means separate transformer windings. (And rectifier, cap, regulator.)

You won't find this in one lump at Allied or Mouser. Weber has one, and there are others, offered through stompbox vendors.

Multiple transformers are an option; look on surplus sites for good deals on a 10pack of small transformers. (Good Luck!)

It is equally valid to convert direct to DC, vibrate that to AC at a higher frequency, then use smaller transformer again with separate windings. The higher freq allows a smaller transformer. Within limits you can incorporate reasonable regulation centrally instead of on each isolated output. It's all complex and requires high-voltage with mysterious swithing waveforms. Unless you already work in the field, not an easy DIY project.