Vegetronix Economic Soil Moisture Sensor
Economic Soil Moisture Sensor Probe - VH400
All of Vegetronix soil moisture sensors have the following properties:
Insensitive to salt.
Regulated input voltage
Wide input voltage range
Note: VH400 model is compatible with HOBO U12 loggers only by using the specially designes SSE Electronics. It is also directly compatible with the analog channels of the HOBO U30 and H22 loggers and stations, and the GP2 Data Logger from Delta-T.
The VH400 has a narrow sensing range, and only senses in the immediate proximity, and so is insensitive to differences in the volume of the medium being measured.
If the probe is going to be buried or if the probe is going to be used to measure pots of differing volumes then the VH400 should be used.
Use the VH400 soil moisture sensors in soils where the soil will have higher water saturation.
Use the VH400 where you need an absolute moisture measurement that is independent of volume, as in the case of measuring moisture in potted plants.
See Video: Soil Moisture Sensor as Water Level Sensor
The Techno Gardener demonstrates how a Vegetronix soil moisture sensor can be used as a water level sensor.
The Techno Gardener shows you how to wire up a Vegetronix soil moisture sensor to a digital multimeter.
|Selection Table:||VH400 Series|
|Supply Voltage:||3.3V to 20 VDC.|
|Power on to Output stable:||400 ms|
|Operational Temperature:||-40ºC to 85ºC|
|Output Voltage Range:||0 to 3V|
|Typical Power:||< 7mA|
|Sensitive to Volume:||No|
|Sensitive to salt:||No|
|Frequency of Operation:||80MHz|
|Internal Voltage Regulator:||Yes|
|Applications:||Low power consumption, sprinkler controlers, moisture monitoring of highly saturated soils, monitoring of ground soil and soil in pots of differing volume.|
Most curves can be approximated with linear segments of the form:
where m is the slope of the line
The VH400's Voltage to VWC curve can be approximated with 4 segents of the form:
m= (VWC2 - VWC1)/(V2-V1)
After m is determined, the y-axis intercept coefficient b can be found by inserting one of the end points into the equation:
|0 to 1.1V||VWC= 10V-1|
|1.1V to 1.3V||VWC= 25V- 17.5|
|1.3V to 1.82V||VWC= 48.08V- 47.5|
|1.82V to 2.2V||VWC= 26.32V- 7.89
|Red||POWER: 3.3V to 20 VDC.|
|Black||OUT: (0 to 3V related to moisture content.)|
Some Data Loggers of this list may require the use of the SSE Anticipator with the VH400 Sensor.