I've built a PCB with a 7805 based power supply on it. I tested the other parts of the PCB on a breadboard before I had the PCB made, but as the power supply circuit looked straightforward, I just took it out of a local electronics catalog without testing it.
The problem I'm having is the power supply only outputs 2.8V until you put it under some load. Surely the TIP2955 should not affect the circuit in any way until the voltage drop across the 3 ohm resistor rises above 0.6V? What on earth is going on? I've even taken the components off the PCB and built them on a tag strip. Still only 2.8V until some current is drawn.
It's also worth pointing out that the 7805 is getting quite hot with the circuit at rest. But seems fine when a load (10 ohm 5W resistor, so about 1/2A) is applied.