Turn circuit on when another is broken? Answered
I am having a delema on how I should have my preamp that I am assembling turn on. I don't want to use a toggle switch or anything, because I always forget to turn it off, and I end up draining the battery.
So, I was thinking of having some sort of system that involves turning the preamp on when a 1/4 audio cable is plugged into the jack.
However, I don't want to use the common method, having ground and the second pin shorted by the barrel of the audio cable (jack plug switch is the only name I can find associated with it...)
Thing is, some of the cables that will be plugged into it aren't mono, so it wouldn't work. In fact, if I plugged my headphones into it, it would run 9v through one of the drivers... Don't want to do that.
I noticed the jack I purchased has six pins. Three for audio, and three that connect to the other three ONLY WHEN NOTHING IS PLUGGED IN. When something is plugged in, the three metal contacts are lifted off of the other three pins. Since this device will only be mono, I was planning on connecting the left and the right together. This would mean, that when nothing is plugged in, the other set of pins (that aren't connected to anything when something is plugged in) would be connected, but when something is plugged in, the circuit would be broken.
So, is it possible to use those two pins as a switch? Thing is, I need it the other way around: when the circuit is closed, the amp is off. When the circuit is open, the amp is on.
How would I invert it?
And what gate is it called?
EDIT: A NOT gate is what I am looking for. Is there any simple way of making one, for such a situation? The power supply is 9v, and it would be switching it on and off.