This circuit was found in a Electronics World of 1968. The integrated circuit is the MC1320P from Motorola, uncommon today.
The photo FET is not a common component today. In this 1964 Electronic Design application we have a light...
In the figure we have a basic shield circuit with TTL to TTL optical isolator. For the emitting...
This circuit is from Motorola technical documentation from the 70s, but it can be easily assembled...