This timer, like the previous circuits, uses a currently uncommon integrated circuit. The time is given by capacitor C1 and R2 which has the range of values indicated in the diagram.
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...