We found this preamplifier with 70 dB gain for microphones in American documentation from the 90's. Consumption is low and equivalent transistors can be used.
Indicated for activation by microcontrollers, this circuit was found in the Radio Electronics...
We found this circuit in an English publication in 1991. The circuit can be assembled with...
This tuner circuit was found in an old English documentation. The JFET can be any general purpose...