This circuit, found in a 1964 US documentation, consists of a selective amplifier that lets only 10 Hz pass around a 400 Hz center frequency with the indicated components.
We found this circuit in a Radio Electronics magazine from December 1969. The circuit uses a...
We found this circuit in a 1991 publication. It is intended for low-impedance microphones,...
This circuit can be used in the car to convert the 12 V from the battery in 6 or 9 V up to 2 A....