This interface shield circuit is from the 1983 Intersil Databook. The components used are uncommon today. ADCs are low-cost digital converters. The power source voltage 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...