This circuit was obtained from an American 1980s documentation. The frequency depends on the crystal and the circuit may be a PNP that reaches the generated frequency.
This circuit was obtained in a 1970 EEE and applies to almost any operational amplifier. The...
The circuit shown in the figure generates a square signal (50% active cycle) when the pressure switch...
We found this transistorized AM receiver of the regenerative type of excellent quality in a...