Thanks Brian for sharing, just curious why stereo input Jack? With a mono plug-in aren't you shorting to ground the middle connection anyway? Or am I missing something?
Take a second look at the schematic. Ground for the circuit is connected to ground for the jack, and the middle connection of the jack is connected to the - terminal of the battery. In this configuration, the battery will not be hooked up to the circuit unless there is a cable in the jack. It's like having a power switch without the switch!
Of course, if you plug a stereo cable into the jack, it's not going to work. And if you forget and leave the cable plugged in, it will drain the battery. It's a tradeoff, but if you don't have any power switches handy, it sure beats plugging and unplugging the battery!
Makes sense. Works the same way my pre-amps works, I didn't look close enough at the schematic for a switch. Duh on my part!
Yes, the middle leg of a stereo jack is actually like a switch, they also make mono jacks with this configuration? Thanx for looking fellas :)
I like the simplicity of this. Sometime back I had a garage sale find of a technician's toolbox with all sorts of resistors, caps, ics, boards etc. Will be definitely building a few from your diagram. Thanks, KD