This flip-flop controlled by an LDR-type photocell was found in Radio Electroinics magazine from June 1959. Note that it can be powered from the mains and directly controls a sensitive relay.
This well-known circuit is another version of a 2-transistor transmitter found on the Internet. In this...
This traditional amplifier configuration is from the National Semiconductor's Linear Applications Handbook...
We found this circuit in a 70s Electronic Design documentation. The circuit uses general-purpose...