Radio with amplifier (CB20486E)

We found this circuit in a publication of 1991. The audio amplifier is an operational that admits equivalent.

Antennas for ISM LoRa, SigFox - Antenova
Antenova Grandis antennas can be purchased from Mouser Electronics for frequencies from 868 MHz to...
Crystal AM transmitter (CB20584E)
This short-range transmitter has the frequency determined by the crystal. The frequency can be...
Capacitance Relay (CB4992E)
This capacitance or approximation relay was found in an ancient American documentation. The SCR...