Hi, this my first post! I'm a complete novice with electronics, so please bear with me..
I'm currently making a standalone atmega8l based battery powered project, which I would like to draw 0 power when it's off. However, for various reasons I don't want to have a simple on/off switch, because people could forget to turn the circuit off after use and it would empty the battery in no time.
So my cunning (?) plan is this: I use a separate battery (e.g. a button cell or something), with a pushbutton. The positive side of this connects to the base of a transistor, so that when the button is pushed and held briefly, the circuit turns on. Then, a pin on the AVR which is connected to the same base pin of the transistor is pulled HIGH, so that when the push button is released, the power stays on until i bring the AVR pin to LOW.
I connected up this circuit, and it does start up just fine when i connect a battery to the base and emitter legs of the transistor, or connect the 5v out pin from the VR to the base, but when i disconnect it from the base, the circuit shuts off instantly - even though the AVR pin is high (i verified that it is with an LED first).
Does anyone have any ideas as to why this isn't working as I thought? I will try to provide some pictures of the circuit later, but for now I'm curious if I'm missing something obvious