We found this small audio amplifier in the November 1999 issue of Electronics Now magazine. The integrated circuit used is not very common today.
This circuit triggers a relay when a light beam that hits the phototransistor is cut off. The...
This flip-flop controlled by an LDR-type photocell was found in Radio Electroinics magazine from...
This circuit is from a publication from the 60s. The circuit, with minor changes, can be assembled with...