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 circuit was found in the National Semiconductor's Linear Applications of 1978. The circuit uses...
Indicated for checking the operation of small FM transmitters, this circuit was found in an...
We found this circuit in Radio Electronics magazine from September 1959. The circuit has different...