This circuit was obtained from the April 1978 Radio Electronics magazine. The other circuit is a PLL of the time. The power supply must be 15 V symmetrical.
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...