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.
The circuit shown is suggested by National Semiconductor's Linear Applications Handbook. The base...
With this circuit a logic output signal from a microcontroller or other digital TTL configuration can...
This conventional oscillator with the 741 can be precisely adjusted to produce a 400 Hz signal. The...