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.
This simple optical alarm circuit was found in the 1991 Electronics Experimenter Handbook. The...
This broadband amplifier was found in an Elektor from the 90's. The gain is 10 dB with a noise...
A recreational application of the 4018 is shown in the figure in which we have electronic dice....