I am new to electronics and I am trying to build a DIY Fuzz Pedal. Before I construct it, I am trying to figure out how to use my pedal board's power supply with it instead of using a 9 volt battery. I am not sure of the parts I would need to get to make this work. Any help would be appreciated!

  • \$\begingroup\$ Go buy a cheap wall-wart.... \$\endgroup\$
    – Trevor_G
    Oct 18, 2017 at 18:08
  • \$\begingroup\$ Or even better, a benchtop power supply. Relatively inexpensive models are available at circuitspecialists, etc. \$\endgroup\$
    – JYelton
    Oct 18, 2017 at 18:17

1 Answer 1


As a fellow musician, I applaud your effort, but must point out that the nature of your question leads me to believe you need a lot more information before attempting to build an electronic device.

A power supply (I assume you have a typical AC/DC transformer or "wall wart") and a battery are both voltage sources. As long as the battery or power supply can provide the required current and the voltage is correct, they are interchangeable.

But to address your question more directly, a guitar pedal (at least the ones I have) typically have a "DC barrel jack" which has a negative polarity. In other words, the polarity is the opposite of many other DC devices.

Polarity indicators

The connector on your power supply provides 9 volts, but the outer contact will be positive while the center pin will be negative.

9V Battery Polarity

You can see on a 9V battery that the smaller "male" terminal is positive. As long as the positive (outer) terminal of the power supply connects to the same power input pin on the device as the positive terminal of the battery, the polarity will be correct.

  • \$\begingroup\$ I always thought Boss and such did that just to make people buy their 'specialty' power supplies. Now I think they also do it to be jerks. \$\endgroup\$ Oct 18, 2017 at 18:16
  • \$\begingroup\$ I had an old Casio keyboard do the same thing. There are some potential reasons (electronics.stackexchange.com/q/230369/2028) but I definitely prefer positive polarity. \$\endgroup\$
    – JYelton
    Oct 18, 2017 at 18:19

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