Found in a 1968 American documentation, this circuit generates 1 kHz signals. The SCR used is not a common component today.
This circuit, found in a Popular Electronics from 1978, causes two LEDs to flash alternately for a...
The transformer inf this circuit is a 6 or 9 V unit and diodes 1N4002. The filter capacitor is 2...
This circuit was obtained in a Popular Electronics from the 90's. The gain depends on R4 and R3....