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.
This circuit was found in the July 1969 issue of Radio Electronics magazine. It also appeared in...
We found this circuit in the August 1994 Electronics Now magazine. The circuit is based on the...
This 4.5 MHz oscillator, or according to the crystal, was found in American documentation from the...