I would like to replicate the functionality inside the Ampoids guitar amp (9v battery) in which the circuit is turned on only when you plugin a male 6.3mm mono jack to it

Ampoid guitar amp showcase

I believe that the most common form of this connector is actually a stereo NC type of connector, in which the circuit "breaks" when the plug is inserted in

6.3mm female stereo jack Switched female jack diagram

Is there a way in which I can achieve the desired functionality with a NC female 6.3mm (1/4") connector?, that is: making the 9V battery power on the circuit when a male mono plug is inserted on the switched female connector

I have looked at this article by Brian Smoot on CUI Devices a few times but it explains it in terms of stereo connectors and I get confused.

  • 1
    \$\begingroup\$ yes, there is a way, but it would be easier to find a connector with NO contacts \$\endgroup\$
    – jsotola
    Feb 9, 2021 at 3:02

1 Answer 1


If you are using mono 1/4 inch phone plugs, you can use a stereo jack (no switch contacts needed on the jack).

Connect the ground side of the battery to the ring terminal of the jack rather than to Ground. When you insert the plug, the ring contact of the jack will touch the sleeve of the plug, completing the battery connection to Ground.

  • \$\begingroup\$ Thanks for your input, it makes all the sense in the world. Here is the actual wiring on one of those amps editing a little to increase the brightness I can see the connections are as follow: Signal in (to board) - Ring (battery GND to board) - Sleeve (batter GND IN). so this solves the mystery. \$\endgroup\$ Feb 9, 2021 at 3:32

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