This circuit is from Radio Electronics from March 1977. The integrated circuit is from that time and the circuit is intended for an infrared audio link. The modulation is in pulse frequency.
This well-known configuration that appears elsewhere on the site is from an English documentation. In it,...
We found this simple operating tester 741 in a European publication in 1991. The circuit...
Found in Radio Electronics, this circuit doubles the voltage of the 117V power grid to activate...