We found this circuit in an article in Radio Electronics magazine from November 1971. The circuit has several sensor inputs and is based on programmable unijunction transistors or PUTs.
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...