Operating in the range of 3 to 100 MHz, this circuit was found in documentation from the 70s. Observe the coil. The field effect transistor is a component of the era.
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...