We found this circuit in a 1972 publication. The circuit is indicated for the application of TTL signals for transmission via coaxial cable. The circuit must be powered by a voltage of 5 V.
We have dozens of similar projects in articles and circuits on this site. This is from Radio...
This circuit with an unusual configuration was found in the January 1974 issue of Radio...
This interesting circuit from 1967 documentation uses three series lamps to regulate the voltage...