To calibrate the gauge, connect the battery and press the probes gently into a pot containing a plant that is just on the verge of needing water (stick it in so that only an inch of the probe is left visible at the top). Turn the potentiometer until the `OK` LED lights and then turn it back to the point where that LED goes out and the ''W`, or ' 'Water`, LED just comes on.
The device should now be properly adjusted.
-small.png "CMOS Circuits Tutorial")
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