Switch to open or close two isolated circuits

I want to turn two devices with different voltages on and off at the same time. One is a small amp and the other is an Echo. One is DC 5v, the other DC 12v. I ordered a DPST mini-toggle (SW-T2-3A-A-A2-M2) and connected both circuits, but with the toggle one way, the amp is on and Echo off and the other way, the amp is off and the Echo is on. I thought a DPST switch is what I needed, but clearly not. I thought I wired it wrong, but if both circuits are isolated, then wiring wrong would mean it does not work at all. What am I missing here? Any help would be appreciated!

Welcome to the Digikey tech forum. A DPST switch should do the trick for what you’re trying to achieve. Check to be sure the wires from each circuit are connected to the proper terminals. Here is a link that may also give some insight.

Welcome to the forum.

Based on your description it should be working. So either the wiring is not correct or the switch is defective.

Here’s a diagram of the proper wiring shown schematically and a labeled pictorial diagram.

It’s very easy to test the switch with an ohmmeter.

In the OFF position there must be near infinite resistance between all four terminals.

In the ON position there must be near zero resistance between A&B and between C&D. All other terminal combinations must be near infinite resistance.

Thanks, that is what I thought. After testing, the switch works just fine. Turns out that one device I want to power is an amp and the on/off circuit from that amp turns the amp on when the circuit is open and off when the circuit is closed. So when I connected both devices, it was confusing to see the amp on when the switch was in the off position. I should be able to get the result I want with a 4PDT (on/off) switch. Electronics are not my strong suit, but I am leaning from smart folks like you. Thanks!

Ah, you’re not adding a switch to the amps power, you’re adding an external switch to the amps existing power switch.

Many, possibly most, devices nowadays have a built-in power switch that doesn’t actually switch off power. Instead it tells the computer in the device to go into the lowest power sleep mode. This shortens the delay during the computer start-up vs. cold booting, and lowers cost because power switches are more expensive than input switches.

When I add an extra switch for power control I avoid that situation by simply wiring the switch into the power input cord.

You should be able to use an DPDT switch with one connection using the NO contact and the other connection using the NC contact.

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Great information! I will try the DPDT switch then. Thanks again for the education.