Water_seepage_alarm_using_an_LM3909_chip

Published:2009/7/20 6:00:00 Author:Jessie | From:SeekIC

Water seepage alarm using an LM3909 chip. Circuitry inside dashed lines is the LM3909. Standby battery current drain is 100μA. The multivibrator rate is about 1 hertz when it starts and increases as more moisture passes across the sensor. The sensor should be part of the box housing the circuitry. The sensor consists of two 6-inch strips of metal about an eighth-inch apart. Stainless steel or copper will work well. Battery life for a single alkaline penlight cell is about 3 months (courtesy National Semiconductor Corporation.)



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