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 was originally indicated to receive the signals from CIR1178. However, it can be used...
In fact, this 1986 documentation circuit consists of a set of rhythmic LEDs that blink to the...
Signals ranging from a few millivolts to a few volts can be used to excite a relay with this...