This circuit uses a transistor to trigger the alarm from a low quiescent current sensor. The relay is 12 V. The circuit is from Radio Electronics magazine, April 1975.
This circuit was obtained from an old American documentation having a limited adjustment range....
The movement of the LEDs in this circuit mimics the back-and-forth movement of a pendulum, making it...
This circuit is from a 1967 documentation. It makes use of varicap and diode tunnel in addition to...