IC Relay? Audio Patchbay

Thread Starter


Joined Dec 7, 2015
Okay, so I have an interesting patchbay design that I need help with.

I have a 12v DC Magnetic-Lock that will be active, and magnetizing a secret door. To get the secret door to open, the circuit to the mag-lock must be broken.

I have two options. My first option would be to run the mag-lock signal straight through the patchbay, and create a parallel circuit so that when it is patched correctly, all of the "normals" break which breaks the circuit, opening the door.

My second option would be to use a Relay or some type of IC-Chip to go between the mag-lock and the patchbay, so that when patched correctly, the patchbay creates a full circuit to the relay, triggering the off switch for the mag-lock.
Unfortunately, I know absolutely nothing about Relays or IC-Chips. Can somebody help?

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Joined Feb 5, 2010
I will assume somethings to start.

If using 1/4 inch mono plug Jacks you could use stereo Jacks and plugs and wire all the un-used audio connection in series through your plugs.

If you made it have three "key" Jacks and three special stereo plugs then only by putting those three special plugs in the three key stereo Jacks would you complete a series of ground connections to bring a ground potential out to your relay.


Joined Aug 1, 2013
The difference between your two methods is having the patchbay contacts switching the mag-lok power directly, or switching a control signal to a power switch. The latter method is vastly superior in terms of reliability, because the jack contacts will arc whenever the DC power to the coil is interrupted. This is a small scale version of what fires spark plugs in a car, called an inductive kick. Seems like a rude thing to do to an unsuspecting jackfield.

While there are many ICs that will do this job, so will a single transistor with one resistor and one diode.

What is the steady-state current for the mag-lok?