This circuit is from a Motorola documentation from 1968. The integrated one is an operational of the time still in metallic casing. Modern equivalents can be used.
Found in a 90s Popular Electronics, this circuit triggers a load from the audio signal applied to...
This old receiver (1967) uses germanium transistors from the time and coupling transformers,...
I found this circuit in a Popular Electronics from 1992. The circuit can be easily implemented with BC549...