Environmental Sensors

Need a new type of sensor? Interfaced a sensor that you want to tell everyone about?
black_unicorn
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Environmental Sensors

Postby black_unicorn » Wed Apr 25, 2012 9:58 am

Good morning:

I'm thinking of sensors to build a weather station.

- Wind Speed ​​Sensor
- Rain Sensor
- Solar radiation sensor
- Soil moisture sensor

Greetings!

borisg
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Re: Environmental Sensors

Postby borisg » Thu Apr 26, 2012 12:47 am

The Phidgets light sensor is too sensitive for quantifying solar radiation and would need filters to reduce the light intensity to <1000 lux. The old Phidgets light sensor was insensitive enough, or you could salvage one of the photocells from a night light that turns itself off in the daytime. Alternatively, one could use a solar cell and measure the current through a load resistor which would be proportional to sunlight intensity.

One source of soil moisture sensors I'm testing are made by Vegetronix (http://vegetronix.com/) and they run off 5 V and produce a voltage in the range of 0-3 V which can be converted to soil moisture percentage by a piecewise linear approximation. They can also be used as fluid level sensors. I used a Phidgets A/D connector to easily connect it up to an 8/8/8 board. I've tested the VH400 soil moisture probe only.

As far as a rain gauge goes, I suppose you could use the Vegetronix 400 in the fluid level measuring mode and have some sort of mechanical actuator dump the contents of the rain gauge when it gets full.

Haven't decided how to best do the wind speed sensor yet as I'm still looking for a simple means of quantifying wind direction. Putting a propeller on an electric motor will give a voltage proportional to the rotation rate and the system can be calibrated by mounting it on the outside of a vehicle and driving at various speeds.

The IR sensor can be used as a cloud sensor as the back-radiation one gets from a cloud is considerably warmer than from clear sky. There hasn't been enough completely dry weather lately where I live for me to risk trying this as I don't think the IR sensor would like rain very much. The IR sensor has an on-board temperature sensor which has a relative accuracy of better than 0.1 C.

black_unicorn
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Re: Environmental Sensors

Postby black_unicorn » Thu Apr 26, 2012 5:22 am

Dear borisg:

Thank you very much for the information, primarily by the probe VH400 Series.

The radiation sensor I have solved it with a solar cell and a resistor.

The wind speed sensor at first I built and caliber, so does the rain gauge.

Now, for the wind speed sensor and rain sensor I have no luck in getting the equivalent type. That is, that run on 5 V and produce a voltage in the range 0-3 V.

I even tried to get digital to allow me to use the D input of a Phidgets 8/8/8, but no luck.

Do you know where to get them somewhere?

Thank you!

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burley
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Re: Environmental Sensors

Postby burley » Thu Apr 26, 2012 7:24 am

My recommendation for a windspeed sensor is to build your own anemometer. You can use an encoder on the shaft of the anemometer to determine the speed at which it is rotating. This will allow you to calculate windspeed.
Brian Burley
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support@phidgets.com

black_unicorn
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Re: Environmental Sensors

Postby black_unicorn » Tue Jun 12, 2012 7:04 am

Dear borisg:
You told me: "... One source of soil moisture sensors are made ​​by testing'm Vegetronix(http://vegetronix.com/) and they run off 5 V and produces a voltage in therange of 0-3 V can be converted to Which soil moisture by a piecewiselinear Percentage Approximation. They can Also be Used as fluid levelsensors. I used to Phidgets a / D connector to connect it up to Easily an8/8/8 board. I've tested the soil moisture probe VH400 only ... "

I would like to ask you this: Did you connect directly to the sensor or is there some intermediate stepin order to communicate the sensor with Phidgets board?

As I can convert sensor input to a reading in Volts, and then make calculations? (getSensorValue(int index)
* 0,005), is correct for NonPhidgets Sensor?

Any tip to help before starting to test this sensor?

Thanks.

black_unicorn
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Re: Environmental Sensors

Postby black_unicorn » Tue Jun 12, 2012 8:11 pm

I share the solution I developed and worked perfectly for my purpose:
My starting point was: How to get a sensor reading consistent with Phidgets? My sensor supports input from 3.3V up to 20 v and returns an output between 0V and 3V.

My solution:
(getIk (). getSensorValue (Puerto_Entrada_Analoga_Humedad_Suelo) * 5.0) / 1000.0

This gave me back the voltage sensor.

I can not say it is the best or the most optimized, but it worked for my needs.

Until next time.

szahran
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Re: Environmental Sensors

Postby szahran » Thu Aug 08, 2013 12:59 am

Hello,

I'm interested in knowing how to connect the soil moisture sensor (http://www.vegetronix.com/) to the phidget 8/8/8 board.

Would you please let me know, how you connected it with the board?

Also how accurate were its readings, and how could you interpret the sensor value into a soil moisture value or indicator ?

Thanks in advance!

black_unicorn
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Re: Environmental Sensors

Postby black_unicorn » Thu Aug 08, 2013 5:32 am

szahran wrote:Hello,

I'm interested in knowing how to connect the soil moisture sensor (http://www.vegetronix.com/) to the phidget 8/8/8 board.

Would you please let me know, how you connected it with the board?

Also how accurate were its readings, and how could you interpret the sensor value into a soil moisture value or indicator ?

Thanks in advance!


Hello szahran:

Red Vegetronix to Red Phidgets
Black Vegetronix to White Phidgets
Bare Vegetronix to Black Phidgets

To read the voltage applied to the following formula:
(getIk (). getSensorValue (Puerto_Entrada_Analoga_Humedad_Suelo) * 5.0) / 1000.0

Finally, the applied voltage obtained for the conversion:
http://vegetronix.com/Products/VH400/VH400-Piecewise-Curve.phtml

Good luck!

szahran
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Re: Environmental Sensors

Postby szahran » Thu Sep 05, 2013 12:39 am

Thanks black_unicorn!

I recently got the sensor and I wired it the way you described. I could see the sensor values in the phidget GUI.

I got values like 13(sensor in the air), 75(sensor in soil), 262(the tip of the sensor in water), 500 (sensor completely in water).

I applied your formula to those values:
13 -> 0.065
75 -> 0.375
262 -> 1.31
500 -> 2.5

As I understood those converted values are the voltage value, is it like the higher the voltage the more moist soil it is? I'm not quite sure how to correlate this to the equations in http://vegetronix.com/Products/VH400/VH ... urve.phtml

Basically all I need is to correlate the sensor values with the state of the soil in terms of moisture and the larger the scale is the better the results.

Another thing I'm using the Java API to read the sensor values, is

Code: Select all

(getIk (). getSensorValue (Puerto_Entrada_Analoga_Humedad_Suelo) * 5.0) / 1000.0


different than

Code: Select all

sensorBoard.getSensorValue(sensorId);
where sensorBoard is an instance of InterfaceKitPhidget and sensorId is the index of the sensor.

I would appreciate your reply.

Thank you very much,
szahran

black_unicorn
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Re: Environmental Sensors

Postby black_unicorn » Thu Sep 05, 2013 5:39 am

What you need to do is the following:

Double VWC = 0L;
Double voltage = ....
if (voltage> = 0.0 && <1.1) {
VWC = 10.0 * (voltage) - 1.0;
} else if (voltage> 1.1 && <1.3) {
VWC = 25.0 * (voltage) - 17.5;
} else .......


Do you understand?

Other important thing to keep in mind:

Soil's holding capacity is less than 50%, so Vegetronix only calibrate to 50%. Above 50% you can use to straignt line as an approximation -

Provide only Vegetronix curves for a single soil type. It's possible the curves could vary for other types of soil. Most soils do not have a holding capacity above 50%. Sandy soil holds the Least amount of water <50%.

See too: http://www.vegetronix.com/TechInfo/How- ... -VWC.phtml


szahran wrote:Thanks black_unicorn!

I recently got the sensor and I wired it the way you described. I could see the sensor values in the phidget GUI.

I got values like 13(sensor in the air), 75(sensor in soil), 262(the tip of the sensor in water), 500 (sensor completely in water).

I applied your formula to those values:
13 -> 0.065
75 -> 0.375
262 -> 1.31
500 -> 2.5

As I understood those converted values are the voltage value, is it like the higher the voltage the more moist soil it is? I'm not quite sure how to correlate this to the equations in http://vegetronix.com/Products/VH400/VH ... urve.phtml

Basically all I need is to correlate the sensor values with the state of the soil in terms of moisture and the larger the scale is the better the results.

Another thing I'm using the Java API to read the sensor values, is

Code: Select all

(getIk (). getSensorValue (Puerto_Entrada_Analoga_Humedad_Suelo) * 5.0) / 1000.0


different than

Code: Select all

sensorBoard.getSensorValue(sensorId);
where sensorBoard is an instance of InterfaceKitPhidget and sensorId is the index of the sensor.

I would appreciate your reply.

Thank you very much,
szahran


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