I found tis circuit in na old documentation from 1958. The circuit uses germanium transistor availble that time and hard to obtain today. The circuit is indicated for phono applications using variable reluctance transducer.
This circuit can be implemented with standard photodiodes consisting of a two input optical AND gate....
This TTL counter was found in the March 1991 issue of Radio Electronics magazine. The circuit is...
The circuit shown in figure uses a photodiode as a sensor element and its main feature is to have...