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 was found in an English publication from the 80's. It triggers a buzzer (with...
The SN72741 integrated circuit is nothing more than the version of Texas Instruments of the known...
This simple circuit connects in external battery to a load when the AC Power line fails. S1 can be...