This circuit visually indicates that a high voltage is present in an outlet or other point. The neon lamp is common, and the appearance of the assembly is suggested in the same figure.
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...