Found in an American documentation from 1969, this astounding circuitry makes a relay operate on 3 Hz cycles. The relay is of the high voltage type of the time.
This circuit was obtained in a 1980 publication, but it can be easily assembled today, as all...
This interesting manual circuit uses an SCR to switch a load on and off via pulses. The circuit was...
This Schmitt optical trigger with LDR was found in old documentation. The relay must be sensitive, or an...