SOIL_MOISTURE_MONITOR

Published:2009/7/17 3:58:00 Author:Jessie | From:SeekIC

In the circuit, when R6 equals the value of the resistance of the soil between the two probes, the bridge circuit is in balance. To set up the circuit, bring the soil that you wish to monitor to the proper moisture level and insert the two probes into that soil. Then adjust R6, until the two LEDs are both off, or at least dim to the same level. The two LEDs serve as a null indicator. That is, LED2 is on when the ground resistance is higher than the preset resistance of R6, and LED1 is on when the ground resistance is lower than the preset value. When both LEDs go dark or dim to the same brilliance, the bridge circuit is in balance. At balance, R6 equals the ground resistance. The probes are two 6-inch by 1/16-inch round stainless-steel rods mounted about 1 inch apart in an insulated handle.



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