This circuit can function as both a light alarm and a shadow alarm. The components are common. The circuit includes the power supply. Output transistors must be mounted on heatsinks.
In this circuit the capacitor under test is charged at switch position A and then discharged...
This is a common circuit in the 1990s, when experimental FM transmitters were in vogue. The...
Using a piezoelectric sensor of the time, this circuit was found in the February 1994 issue of...