Door Alarm


Posted on Apr 14, 2012

This circuit emits a beep and/or illuminates a LED when someone touches the door-handle from the outside. The alarm will sound until the circuit will be switched-off. The entire circuit is enclosed in a small plastic or wooden box and should be hanged-up to the door-handle by means of a thick wire hook protruding from the top of the case. A wide-range sensitivity control allows the use of the Door Alarm over a wide variety of door types, handles and locks. The device has proven reliable even when part of the lock comes in contact with the wall (bricks, stones, reinforced concrete), but does not work with all-metal doors.


Door Alarm
Click here to download the full size of the above Circuit.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Dremel Speed Controller
100W 420-450Mhz push-pull linear amplifier
2 channel 100W min AF Power Amplifier STK4231II
switch mode power supply How does this circuit regulate voltage
Transistor current limit circuit power handling
roboat
Electronic siren circuit
OPB350 Tube Liquid Sensor
Circuit Project: Wireless Doorbell
Reference earphones
Single-ended four-channel amplifier schematic
DAC0832 single - bipolar voltage output interface circuit



Top