We found this circuit in an American publication from 1977. The circuit drives two LEDs according to the control of the inputs. The technology is TTL requiring 5 V to power supply.
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...