This is a traditional 741 configuration with gain close to 100. We found it in the December 1972 Radio Electronics magazine. The power source must be dual.
This circuit for a 455 kHz ceramic filter was found in the October 1952 Radio Electronics...
This circuit was found in a Poptronics of the 90's. It can be powered by voltages between 6 and 15...
The microphone of this short-range MW transmitter should be low impedance magnetic (a small...