This 80's Exar circuit has a carrier detector for frequencies up to 500 kHz. The circuit uses a company 567 which is still a common component.
I found this circuit in an article in a 2003 publication. The circuit is an example of how to...
The L coil of this receiver determines the received waveband. The circuit is from a 1963...
This circuit is from an old American publication, using transistors of the time and operating with a 48...