Found in a 1992 book, this circuit is intended for operation with audio signals. Equivalent operational amplifiers can be used. The optical coupler is an unusual type today.
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....