This circuit was found in a 80's Popular Electronics. The sensor can be any phototransistor. The circuit is indicated for an audio link modulated in pulses.
This circuit is from an old French publication. With it we can have full wave control of a charge...
This is an improved version of the previous circuit also found in the December 1990 Radio...
This VCO with the 4046 PLL generates signals from 0 to 1.5 kHz. The circuit is from a Radio...