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.
The integrated circuit used in this stereo preamp is uncommon today, but the circuit can be...
This circuit was found in a 1967 General Electric manual. It is intended for the control of high...
Carbon microphones are no longer used in most projects. However, finding one in the scrap metal, it...