This circuit is from an old American publication. It divides a 40 to 60 MHz TTL signal by integer values such as 2, 3 or 4. The circuit must be powered by 5 V.
This circuit is from 1964 documentation but can be easily implemented based on current components....
This Power supply sources from 500 to 1,000 mA according the transformar and was found in a...
This photo-relay uses a Darlington stage to increase sensivity. Any photo-transistor can be used....