transistorsvirtual-ground
I designed and prototyped the circuit below. The circuit works as expected but Q2 is getting really hot during operation. I simulated it in LTSpice and saw that Q2 draws more current but the range is in 700uA.
The input voltage in prototype is around 20V. What may be the reason for the increase in temperature of Q2?
simulate this circuit – Schematic created using CircuitLab
I achieved something similar with the below circuit. Does use some extra components, but will happily switch the 12V on and off!
Whilst I think this achieves what you're looking for - i've found it to be better to use a transistor to switch the path to ground on or off, rather than using it to turn the 12V supply on.
See Below;
simulate this circuit – Schematic created using CircuitLab
By shorting out the collector-base junction you have converted the transistor into a diode. Diodes can't amplify current. The circuit will not oscillate.
Best Answer
This is something close to what I'm thinking about. It's really not all that different from the usual class-AB power amplifier stage of an audio amplifier.
simulate this circuit – Schematic created using CircuitLab
This circuit includes some details to handle BJT variations and using the Sziklai arrangement helps circumvent issues related to heating in the power BJTs, \$Q_1\$ and \$Q_2\$. You will need to adjust \$R_{14}\$ to set the quiescent current (just measure the voltage across \$R_1\$ or \$R_2\$ while setting this.) I've also included \$R_{13}\$ to handle the Early Effect of \$Q_5\$ and \$R_{16}\$ to deal with accidental shorts (you can remove it, if you want, by simply bypassing it with a wire.) \$R_9\$ and \$R_{10}\$ are there to avoid oscillation and to help match BJT vagaries. But they also can be removed (bypass them) if you want.