This circuit is from a 1976 amateur radio manual. The transistor can be the BD136 and the frequency adjustment is done in a potentiometer. The supply can be done with voltages from 6 to 15 V.
This MOSFET circuit for microphone applications was found in the December 1969 issue of Radio...
This operational amplifier circuit with power output using complementary transistors was found in a...
This circuit is from a publication of the 70s, but it can be easily assembled with the BC548. The...