This small tone generator was found in the November 1987 issue of Radio Electronics magazine. The phototransistor is common and controls the sounds generated. The basic frequency is given by C1.
We found this circuit in the June 1991 issue of Radio Electronics magazine. The integrated circuit is...
This circuit was found in a 1967 RCA documentation. The components are of the time. The circuit...
This timer for short intervals was found in a documentation from 1966. The transistor is made of...