Power Supply PC Board

This is the complete schematic for the circuit that is contained on the AMZ Power Supply PC Board. It features 5 linear voltage regulators and a voltage converter chip that outputs -9v to power PNP pedals that require negative voltage. The basic idea is to create a single pc board that can be used to produce clean, noise-free power for your pedals.

A DC power supply (not included) is required as a voltage source to drive the Power Supply pcb. An 18v transformer is recommended because the input voltage is filtered and available as one of the outputs, but any DC wall adapter with 14v to 18v is suitable.

Multiple filtered and regulated dc voltages are available on the board. IC1 through IC5 are 7809 regulators but I usually substitute a 7812 regulator for IC1 so that I have a 12v output too.
The input voltage is filtered and also available; if the input voltage is less than 18v then the corresponding output will also be less since it is just a filtered version of the input.

A DC wall adapter that can provide 18v at 1A is recommended but transformers with current down to 750ma or less can be used as long as the total draw from all of the outputs does not exceed the capacity of the adapter.

This is the blank 3.0" x 1.5" Power pcb. It has an optional LED (with current limiting resistor) on board to indicate when the board is energized.

The voltage from IC5 is processed through a diode and series resistance as a way of imitating voltage sag from a dying battery. It is easy to bypass this feature if not required and use the IC5 voltage as an additional fixed 9v output.

Each of the IC1 - IC5 regulated outputs can easily supply 150 ma or more. The TO-220 regulators are rated for 1A each but I do not recommend drawing that much current from any one of the outputs as excess heat may be produced inside the box.

How much current does a typical pedal draw? A booster like the LPB-1 or Mini-Booster will need less than 2 ma. and a distortion such as the TS-9, SD-1, Big Muff or Proco Rat will use less than 8 ma. Analog chorus or delays will need less than 20 ma and digital devices use slightly more (45 - 75 ma). Check out the power list for information on the current requirements of many common effects pedals.

The negative 9v converter has less current capacity but can easily drive a PNP booster and fuzz circuit at the same time.

A pedalboard with a booster pedal, two distortions, and 8 more assorted pedals will typically draw less than 500 ma, which is well within the capacity of this design.

The power outputs share a common ground, and though it should work well with the majority of pedals, there are a few designs (mostly digital) that will require a power input with an isolated ground to avoid hum.

The AMZ Power pc board can supply the following:

• +18v filtered power (depending on your wall adapter voltage)
• Multiple +9v regulated power outputs (enough to drive 10 or more pedals)
• Low voltage sag output for dying battery simulation
• Negative 9v for PNP boosters and fuzz boxes
• and more!

Order the current version of the power pcb from the Catalog Page.