We found this circuit in the Encyclopedia of Electronic Circuits Volume 5 from 1995. It uses a 3-terminal transducer from the time. The circuit is triggered by light.
This is a 1960s amplifier setup found in a period publication. The circuit uses a special driver...
The purpose of this circuit is to extend the range of frequency meters (typically up to 30 MHz) to...
This circuit was found in a documentation of the 80's having characteristics of high overvoltage given by...