We found this circuit in the October 1996 Electronics Now magazine. The circuit uses LDRs as sensors and drives relays. The relays must have voltages according to the power supply.
When a pulse of light reaches the sensor [a CDs cell or LDR] the flip-flop changes its state....
This circuit is an impedance adapter. The circuit is from a Radio Electronics from April 1966. The...
This circuit was obtained in an old American documentation serving only for general purpose NPN...