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 squelch circuit is placed at the input of the single receiver audio amplifier stage. Its...
This circuit was suggested by Texas Instruments in a 1980s documentation. The transistor must be...
We found this circuit in a European publication of the 1980s. The transistor could be the BC549. The...