Hey, I'm doing similar things at the moment - trying to make a test-array of various voltage controlled modules. Things are starting to give great sounds....
I wanted to do synth modules for ages, but not knowing much about power supplies put me off. Then I saw a couple of mentions of using AC - AC wall wart adaptors followed by voltage regulators to give bopolar supplies. This method is certainly used by the new Paia ribbon controller module (Paia article
)and i think its also used for the cheap'n'simple doepfer power supply unit.
There's still some things I'm not entirely sure on - - so I'd appreciate any comments...
I'm using a 25v AC supply (from 240v UK supply), but I think you can use down to 12v - does this change how much current the circuit can supply?
The two input resistors - the Paia article says 1K, but I tried this and the supply didn't work properly - I changed these to more like 60ohms (i think).. do these set the maximum current? The 1st prototype I left them out & it all overheated badly...
Caps C1&C2 - smoothing - I'm using 220u
Voltage regs - using LM7812 & LM7912 plus heatsinks
C3,C4 - 10u or 100u
I then use 4 pins for distributing the power - see the board layout for the rough idea - AC in on the left, then diodes, smoothing caps and vregs on the side (I thought to bolt them onto the side of the enclosure), then the pin distributors with plenty of space.
This power supply has made my recent testing so much quicker and easier! I've had up to about 4 modules at a time running, but haven't yet measured the current draw .. thats something I really ought to do..
So....here's the schematic]http://www.bugbrand.co.uk/schems/bipolar_power_supply_uses_ac_transformer.jpg[/img]
& the board layout (in eagle):