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.
This circuit triggers a relay when the detected humidity falls below a value. The system can be...
We found this circuit in an old General Electric documentation. In fact, PUTs are not common...
This alarm circuit was found in a 1997 publication. It uses two reed-switches to arm and disarm the...