DOOR AJAR MONITOR


Posted on Feb 7, 2014

The monitor senses an ajar door and, if the situation isn`t corrected within 20 seconds, sounds a beeping alarm. The circuit is controlled by a magnetic reed switch and magnet on the door. With the door closed, the switch is closed and the alarm is disarmed. Opening the door opens switch, C1 starts charging up through R1. Approximately 20 seconds later, th..


DOOR AJAR MONITOR
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