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.
This circuit is from a 2005 Linear Technology application manual. The circuit uses a commercial...
We found this circuit in an English publication from 1982. The power MOSFET can be of any type and the...
We found this circuit in a 1982 documentation. An intercom to be good must be sensitive and have...