Using a 74123 TTL this circuit was found in the Radio Elecronics magazine of June 1975. The power supply must be 5 V. The capacitor determines the activation time.
We found this circuit in a 1977 publication for radio amateurs. It serves to test general purpose...
This circuit is from a 1998 Poptronics. The circuit triggers a buzzer after a certain time, waking...
This circuit for electronic voltmeter was found in a publication by Gernsback from 1960. The...