Based on a PLL 567, this circuit serves as a receiver for the CB9574E circuit. S tuning is done in R1 and it is used for frequency modulated signals.
This circuit is from the 1960 Mullard transistor manual. The transistors are germanium from the...
This circuit, which may have other applications, trips a load if the voltage on the telephone line...
This circuit was found in a 1986 documentation and can use any operational amplifier like the 741...