This circuit can be used with 3 receivers and is intended for low frequencies (medium wave range). We found it in the September 1995 Electronics Now magazine.
This oscillator has its frequency controlled by crystal and its frequency can be between 100 kHz...
This small crystal microphone transmitter was indicated in an 80s spy book. The range depends on...
The circuit shown is from the 1994 Linear Applications Handbook by National Semiconductor. The...