# Pedal Board Power Supply



## Jimmy_D (Jul 4, 2009)

I needed a power supply to build into a new pedal board project, and I wanted something a little more old-school-heavy-duty with 12 to 15 outputs. More than a couple of Isobricks powered by wall warts, something that wouldn't be so taxed it could give years of trouble free service. Also I had my doubts about how well regulated those Isobrick types are and exactly how much power they can supply.

After looking around for something better everything seemed to be some kind compromise (not enough outputs) and too expensive, so I figured I could make exactly what I needed for less - so I went to my trusty old text book collection for guidance and to poach a circuit, consulted the internet to see what's new since the 70's and made sure I was good, then sketched out my circuit as a layout for stripboard (which I mostly followed except power ended up going into the regulators behind the heatsink instead of in front) so I could power;

Carl Martin Ocatswitch
Strymon Mobius
1 KOT
1 Mini Timmy
8 Typical pedals (inc 2 reverb)

The circuit is for twelve 9 volt outputs and three 18 volt outlets (only one of the 18volt outputs is currently being used via an adaptor as 9volts to power the gashog Mobius), so 15 outputs total.

Outputs are broken down into 5 banks of 3 - four banks are regulated by its own LM7809 and one bank by an LM7818 (these also provide some thermal overload protection)

I apologize for my supposed "layout" below, but in English it's basically -

Hammond 166N24 120v / 24vac (4amp) transformer into fullwave bridge rectifier (4x IN4007 diodes)
Across 4 x 330uf (in parallel) electrolytic filter caps
Into one of five LM78XX voltage regulators on a heatsink, each one backed up by .33uf and .1uf capacitors

I'd be interested in what our resident experts think about the circuit and component values, so far it's worked flawlessly, the rig it powers is dead quiet and this thing generates almost no heat with all 12 pedals turned on for hours. I'm also now convinced that one reason this rig sounds so much better now than it did before, is that it was running low on power because of the wall Isobrick wart power supply.

It's a bit crude on the outside but it's buried inside a pedal board so I didn't spend too much time on appearances, as you can see...


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## player99 (Sep 5, 2019)

Amazing!


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## Latole (Aug 11, 2020)

Very nice job , congrat.


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## greco (Jul 15, 2007)

VERY impressive!


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## Paul Running (Apr 12, 2020)

Nice creation! Gotta love them 3-terminal regulators.


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## taken (Feb 5, 2006)

Very cool!


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## Jimmy_D (Jul 4, 2009)

Thanks gents. Having recently built the power supply above and one of those voltage reducing "Brown Box" things that Stew Mac sells (that I ended up selling), my own cheap wall wart powered 9v supply stroked out, so I decided to make myself a combo unit and I have the following contraption to show for my efforts.

It's got two separately fused transformers supplying two independent circuits.

The voltage reducing circuit as pointed out by JB Welder in the Tone Preserver thread, is a simple bucking coil setup. It has one outlet that supplies wall voltage and one outlet with switchable reduced supply between -6% and -12%, both with what turns out to be a very accurate LED panel meter.

The 9v supply is pretty much per the layout above except I used Mylar caps instead of ceramic and 500uf electrolytic caps (both because I had them on hand). I didn't need any 18v outputs so I have 5 outputs @ 9v - 600ma using 5 x LM7809 regulators and a Hammond 120vac/16vac transformer.

It's in a 2 3/4" x 5 3/4" x 10" aluminum enclosure and weighs in at exactly 6lbs, which is crazy but it should last as it's pretty heavy duty and even better, it works perfectly and runs dead silent. 

I'd encourage anyone interested to build either circuit and I'd be happy to discuss if you do or if you gents have suggestions, thanks, Jim










Voltage reduction side










9V supply side










Done


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## greco (Jul 15, 2007)

Once again, beautiful work!
So impressive.
Congrats!


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## nonreverb (Sep 19, 2006)

Great job!


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## YellowChecker (Jun 10, 2021)

Wow! They look really nice and clean


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## Latole (Aug 11, 2020)

Congrat , nice job


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