I have I circuit that I built and it is powered by a 9v battery. On the board I am using a LP2950 5v regulator TO-92 package. I would like to turn off the battery when the voltage falls to 7.5V. I have been experimenting with a 7.5V zener, cathode attached to the the positive terminal on the battery, the anode to a 1.2k resistor and that same resistor connected to the base of a 2N3904 transistor. The collector of the 2N3904 connects to the ground leg of my LP2950 regulator, the emitter connects to battery ground. This seems to work but instead of turning the transistor off instantly, it is cycling the power on/off until finally the battery is disconnected. I have very little landscape on the PCB to work with so I am trying to keep this as small as possible.
Any suggestions?
Thank you
Any suggestions?
Thank you