On my project, I want to use a transistor to cut power to a servo when not used. Im controlling the base of the 2n2222 with a logic pin from my uC (attiny85), linked with a 220ohm resistor to limit current to its base. My servo uses 100mA, and 2n2222 has a max collector current of 800mA so I should be good.
I can place the emitter-collector between battery GND and servo GND, or between battery VCC and servo VCC, and both seem to work, but it's problematic. (I know electrons flow from emitter to collector, and not the opposite, so I put the emitter on the battery side when I put it on GND, and vice versa when on the VCC side --- I tested flipping collector and emitter and current doesnt flow).
So it works, but I noticed on my multimeter that it consumes around 300uA when I put it on the GND side?? when I put the transistor on the vcc side, no energy is wasted. I'd place it on the vcc side instead, but it makes the servo move weakly, which I don't understand why either, because it moves just right when I place the transistor on gnd.
So, for now both have a disadvantage, but I can't explain why any of this happens.. I tried with a mosfet connected to GND of the servo but the same 300uA are wasted?? anyone has an idea? thanks a lot!