This current boosting circuit uses an op-amp and 3 transistors. The current depends on Q1. The circuit is from the 1995 Encyclopedia of Electronic Circuits Volume 5.
Found in a 1964 Electronic Design, this circuit must use transistors according to the supplied...
This circuit powered by photovoltaic cells was found in the November 1998 issue of Electronics Now magazine....
This low impedance microphone preamp uses an operational amplifier with FET. The power supply must...