We found this configuration in documentation from the 1980s. It applies to almost any operational amplifier and in this version requires a symmetrical power supply.
Found in a publication by Gernsback from 1960, this circuit makes use of germanium transistors of the time....
To control relays or DC motors safely with double isolation via the parallel port, we suggest the...
This circuit is from a 1975 Sperimentare (number 11). The circuit uses optical coupling for a...