@▷ Gate Alarm Diagram | Diagram for Schematic

Gate Alarm Diagram

Gate alarm schematic diagram 277x300 Gate Alarm Diagram

Above alarm is a simple gate alarm circuit based on IC 4093B.

IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate (or window, etc.) is opened. The circuit is intended not so much to sound like a siren or warning device, but rather to give the impression: “You have been noticed.” R1 and D1 may be omitted, and the value of R2 perhaps reduced, to make the Gate Alarm sound more like a warning device. VR1 adjusts the frequency of the sound emitted.

IC1d is a timer which causes the Gate Alarm to emit some 20 to 30 further pips after the gate has been closed again, before it falls silent, as if to say: “I’m more clever than a simple on-off device.” Piezo disk S1 may be replaced with a LED if desired, the LED being wired in series with a 1K resistor.

Please check the figure 2 about how to install the reed switch. You may using other types of switch, your creativity is absolutely important to get best result in switch installation.

Source: http://www.zen22142.zen.co.uk/Circuits/Alarm/Galarm.html

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