This circuit emits a warning sound when night falls. The circuit is from a Hands On Electronics from the 90s. The Sensor is a common LDR and R6 adjusts the trigger point.
This circuit incorporates the passive control of the previous circuit and was also found in the...
I found this circuit on a December 1976 Radio Elettronica. The Italian magazine no longer exists, but...
This circuit is like the previous one except that it can be triggered electronically. The circuit is...