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Door Alarm
Building: Easy
Program: Easy

Building Instructions



Connect a short wire from the Ultrasonic Sensor to port 4 on the NXT.

Door Alarm Programming

Use the program Door Alarm for your Door Alarm.  This program would be easy to modify if you want to change the sounds, adjust the the sensitivity, etc.


How to Use Your Door Alarm

Set up your door alarm inside a room and pointing across the doorway.   When you run the program, it will detect a person walking through the doorway and sound the alarm!  After going off, the alarm will automatically "reset" and start looking for the next intruder.

Be careful not to point the sensor at a nearby wall, the inside of the door frame, or other object, or it will just sound the alarm constantly!



The Door Alarm program is set to detect something that is closer than 30 inches to the sensor, and it has a pretty wide field of "view", but if you know what you are doing, you might be able to slip in undetected.  Try to see if you can find ways to enter the room undetected, then see if you can modify the mechanical design or the program to fix those weaknesses.

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