Isolated Guitar Pedal Power Supply

My pedal collection outpaced my power supply capacity and was causing me problems. I was getting bad ground loops from the daisy-chained TrueTone wall-wart that I was using as well as dirty power from high current digital pedals that was causing noise in gain pedals. I wanted something relatively cheap with no shared grounds and decent thermal handling so went about designing a power supply.

Circuit Schematic:

The LM78xx voltage regulator chips each have their own beefy TO-220 heatsinks that are rated to dissipate the 65C/W of heat generated by the voltage drop coming off the transformer windings. The diodes in the bridge rectifiers have forward voltages of 0.7V so after full wave rectification, there would be a 1.4V drop from the supplied 10VAC from the windings. Converting to DC voltage by a factor of 1.41 the voltage going into the LM7809s is 10VAC * 1.41 -1.4V = 12.7V. The LM7809 requires 11V at it's input for optimal performance so this value is right on the money and under full load would generate 80C of heat. Given that the transformer will normally not be anywhere near rated load, this is a worst case scenario value and will be much lower under normal operation, generating less heat. T1, T2, and T3 are 115V primary, dual 10V @ 300mA secondaries whereas T4 is a 115V primary, dual 18V @ 350mA secondaries. The transformers are all split bobbin, which reduces the need for electrostatic shielding. T4 has two regulators per channel, first an LM7818 18V regulator in series with a LM7809 9V regulator.

In total the power supply has 10 DC Jacks (8x9v, 2x18V), a maximum total power of 30W with each isolated 9V jack having 3W on tap and the series 9V & 18V chains each backed by 6W. Max current supplied by the isolated 9V jacks is 200mA and the daisy chained jacks can supply 200mA at 18V, 350mA at 9V, or a combination from both resulting in 350mA total draw. The isolated 9V supplies have 320uF of filter capacitance and the 9/18V supplies have 1,410uF. The capacitors are all red Wurth electronics aluminum electrolytics and are rated for 105C operation due to the heat coming off the heatsinks.

Perfboard layout created in DIYLC:

Bill of Materials (With online order hyperlinks):