This circuit was obtained from a 1967 GE SCR manual. It is intended for controlling relays responding to a decrease or increase in temperature.
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...