Found in the 1976 Siemens transistors manual, this circuit works with AM or FM IF signals. In the diagram information is given for the coils.
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...