doubt in using TIP122 transistors

Fabian Salinas L said:

I have a doubt about your answer and I hope it's not a dumb one. Isn't Tip122 switched on or off by a small current on the base?

Click to expand...

Only if it is in a circuit where it is configured as a (saturated) switch. In your circuit in post #1 it is not. A saturated switch is a special case of a common emitter circuit. Your circuit is an emitter follower, one name for a common collector circuit. In your circuit it is impossible for the transistor to saturate, so it is not the most efficient circuit.

ak