The integrated circuits used in this configuration are not common today. The circuit is from the 1983 Intersil Databook. The indicator is 8 digits.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...