Product specifications

DS6420 (Rev. E, 1/4/07)
2-13
Vantage Pro2
TM
Accessories
6420
Leaf Wetness Sensor
For the Wireless Leaf & Soil Moisture/
Temperature Station (# 6345)
The Leaf Wetness Sensor detects the presence of surface moisture. The sensor is an artificial-leaf electrical-resistance
type. It consists of a sensing grid, low-voltage bi-polar excitation circuit, and conductivity-sensing circuit. The
Vantage Pro2 console measures the conductivity across the grid and displays the result as a moisture level, scaled
from 0 to 15. The user may select the threshold level at and above which moisture-hour totals are accumulated.
The sensing grid is a gold-plated etched circuit on an epoxy-glass substrate; the excitation and sense circuits are
encapsulated in black epoxy. The included mounting bracket holds the sensor at a 45° angle to simulate a typical leaf
position and to permit runoff of excess moisture; it may be mounted on a vertical post, pipe, or stake, or on the Sensor
Mounting Arm.
General
Sensor Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Artificial leaf electrical resistance
Excitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bipolar (3V nominal) built-in
Time Constant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 seconds
Attached Cable Length . . . . . . . . . . . . . . . . . . . . . . . . . . 40' (12 m)
Note: Increasing the cable length above the recommended maximum cable length causes measurement error in the form of lower leaf wetness readings.
Cable Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-conductor, 26 AWG
Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modular connector (RJ-11)
Recommended Maximum Cable Length
(see Note 1). . . . . 200' (61 m) using 4-conductor 26 AWG cable
Material
Substrate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glass-reinforced, ceramic-filled laminate
Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 oz. copper, nickel, and 50 µ inch gold plate
Mounting Bracket. . . . . . . . . . . . . . . . . . . . . . . . . . . White powder-coated aluminum
Dimensions (length x width x height)
Leaf Wetness Sensor. . . . . . . . . . . . . . . . . . . . . . . . 4.00" x 2.25" x 2.25" (102 mm x 58 mm x 58 mm)
Sensor Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 in
2
(28 cm
2
)
Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 oz. (.4 kg)
Sensor Output
Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to 15
Dry/Wet Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . User-selectable
Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.5
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.5 to 75 seconds
Input/Output
Supply Voltage and Current . . . . . . . . . . . . . . . . . . . . . . 100 µA (typical) @ 3 VDC
Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 to 3 VDC
Connections
Yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 VDC
Red . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground
Green . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Output