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SMT50 Soil Moisture Sensor

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» Accurate volumetric soilmoisture measurement

» Integrated temperaturemeasurement

» Suitable for any soil type

» Analog voltage output

» Robust and reliable

» Easy installation

» Low cost

01/2018

SMT50 Soil Moisture Sensor

SPECIFICATION

Accuracy: Soil volumetric water content (VWC)» Using factory calibration up to ± 2% (VWC) in mineral soils

with moderate salinity from 0 to 50% VWCTemperature

» Typical ± 0.8°C

Resolution: 8 bit = 0.2% volumetric water content10 mV/°C

Range: 0 to 50% volumetric water contentTemperature: -20 to +85°C

Output signals: Water content: 0 - 3 V linear for 0 to 50% vol. water contentTemperature: 0.5 V + (Temperature in °C) • 0.01 V / °Csee characteristiv curvesStartup time: 300 msOutput resistance: 10 kOhm

Power: 3.3 - 30 V DC, 2.7 mA

Cable length: 10 m

Sensor dimensions: ca. 13,5 cm x 2,15 cm

Data logger compatibility: Any logger capable of appropriate power excitation and suitableanalog inputs

2

01/20183

Wiring color code: Brown: +Vbat (power supply)White: GND (ground)Green: Voltage output temperatureYellow: Voltage output soil moisture

Connector pin assignment:

Characteristic curve temperature:

Voltage to temperature conversion:Temperature in °C = (Voltage in V - 0.5 V) / (0.01 V)Example: Voltage = 1 V → Temperature = 50 °C

Characteristic curve water content:

Voltage to water content conversion:Water content in % = (Voltage in V) / (3 V) • 50Example: Voltage = 1.5 V → Water content = 25%

brow

n

brownwhitegreenyellow

= +Vbat= GND= Temperature= Soil moisture

whi

tegr

een

yello

w

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6Vo

ltage

inV

-25 0 25 50 75 100

Temperature in °C

0,0

0,5

1,0

1,5

2,0

2,5

3,0

Volta

gein

V

0 10 20 30 40 50

Vol. water content in %

INSTRUCTIONS

SMT50 Soil Moisture Sensor