This TTL circuit has a well-known configuration, having been found in a Radio Electronics magazine from December 1980. The power supply must be 5 V.
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...