|I got some nasty noise problems when I tried
to use all effect pedals with just one 9 V power supply.
Problem was solved by using separate power supplies for
digital and analog effects. However, a power supply with two
isolated outputs would be a more elegant solution. Luckily I
had suitable parts to build one.
|Here is the schematic diagram. The mains
transformer has two separate 12 V windings feeding identical
regulator circuits. I used LM317 because I had several of
them. I would have been happy with fixed 9V output voltage,
but I didn't have resistors with just right values - so I
used trimmer pots instead. Voltage can be adjusted from 4,4
to 13,9 volts.