This circuit was found in an American documentation from the 90's. What it does is provide at the output a voltage that is the average of the voltages set for the inputs.
This circuit activates a relay when the sensor receives light. The sensor can be any common LDR,...
We found this circuit in a 1980 documentation. With basic changes, including transistors that were...
When a small air current reaches the piezoelectric sensor, a small audio signal is generated and...