dc42:
The circuit given in reply #5 is missing an important detail. There should be a resistor between the collector of Q2 and the junction of R2 and the base of Q2. Without this resistor, Q1 may overheat due to excessive collector current. Alternatively (and preferably), replace Q2 by a P-channel mosfet.
You meant between the collector of Q1 and the base of Q2 right?
1k should be enough right?
I will eventually (probably) will use pmos and not bipolar but I guess I will get the bipolar first (shipment is already on the way)