This is a circuit for receiving signals from the previous transmitter. The circuit uses a common phototransistor. It was found in the August 1984 issue of Radio Electronics magazine.
With the change of the coil, the circuit can operate at frequencies between 30 MHz and 150 MHz....
The frequency of this Pierce oscillator, found in 1969 documentation, depends on the crystal. The...
This simple circuit can be used to power a simple communication system using ordinary telephones....