This circuit that we found in a 1990 documentation uses an LED as a sensor. The operational amplifier is equivalent to the 741 and the trigger adjustment is made in the potentiometer.
This circuit uses discharge tubes as active elements. The circuit is from a 1960s Signalite...
June 2016 – Mouser Electronics already have in stock the TPS56C215 converter from Texas...
This sensitive signal follower with an LM386 integrated circuit can be used in both audio and RF...