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Moisture Detector

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A bar-graph LED driver is used to drive 10 LEDs to give a relative indication of moisture. The moisture probes are connected so that electrical conductivity due to moisture tends to forward bias Q1, providing a dc voltage at pin 5 of U1 that is proportional to leakage current. Ideally, the probes should be made of stainless steel.


Parts List:
Component: Value: Datasheet: Qty:
Resistor

10K

Not Available 01
Resistor

1K

Not Available 02
Resistor

1.5K

Not Available 01
Resistor 54K Pot Not Available 01
Capacitor 0.1uF Not Available 01
IC LM3914 Available 01
Diode LED Not Available 10
Transistor 2N3904 Available 01