looking for watersensor with voltage output

Hello everybody ;)

I am currently looking for a watersensor / leafwetness sensor with a voltage output. This is basically to switch on / off a ventilation, and the hardware I have to use has only voltage inputs.

This is not for use with an arduino, but i thought that some hobbyist there could have an idea.

I thought about this because I know those arduino sensors that would perfectly meet my need if I could easily convert their output in voltage (0-1 or 0-5 would be perfect).

here are the links : http://www.seeedstudio.com/depot/electronic-brick-%C3%82%E2%80%93-water-sensor-p-682.html?cPath=144 http://www.seeedstudio.com/depot/twig-water-sensor-p-748.html?cPath=144_151

If anybody had a clue, this would make my day !!!

Thanks per advance, Edouard

In essence the sensor changes resistance in the presence of water. To turn this into a voltage simply connect a resistor in series and connect it to a voltage source. The the output across the sensor will be a voltage that changes in the presence of water.

However what sort of voltage change do you need for your equipment and what input impedance does it have? These are important if you want it to work.

Thanks for your feedback, if the sensor is already a 'big resistor', i don't understand why plugging another in serie ? (I've not done electronic since i was 13yo) please explain me again =(

it is possible to adjust the voltage threshold on the input of the equipment I will use (see technical data : http://en.telic.de/telemetry/std32/technical-data-std32.html) My idea was to use the same voltage than the equipment itself which accept 5V. this way I could have a 0 - 5V variation on the input and adjust threshold value according to 'wetness acceptance' of the client.

here are the links : http://www.seeedstudio.com/depot/electronic-brick-%C3%82%E2%80%93-water-sensor-p-682.html?cPath=144 http://www.seeedstudio.com/depot/twig-water-sensor-p-748.html?cPath=144_151

The second link contains the following link - http://garden.seeedstudio.com/index.php?title=Twig_-_Water_Sensor - which contains some schematic and even Arduino (compatible) code how to detect water ON/OFF.

You should be able to use this sensor with a (power) transistor to switch 0/5 V. - http://www.tpub.com/neets/book7/25c.htm -

Or do you need a analog level metering sensor that goes from 0..1..2..4..5 volt??

Grumpy_Mike: To turn this into a voltage simply connect a resistor in series and connect it to a voltage source. The the output across the sensor will be a voltage that changes in the presence of water.

I found this schema http://www.sensorwiki.org/doku.php/tutorials/basic_sensor_interfacing_techniques. If I understand well my sensor is the R1 and I need a small resistance for R2. By this way, when my sensor is dry, it have a very high resistance and ouput voltage is very low, when the sensor gets wet, its resistance drop down to nearly zero and the output voltage rize up to input voltage.

Am I correct ?

robtillaart: The second link contains the following link - http://garden.seeedstudio.com/index.php?title=Twig_-_Water_Sensor - which contains some schematic and even Arduino (compatible) code how to detect water ON/OFF.

The thing is that I don't want to use arduino for this project because arduino board + gprs shield + relay shield is more expensive than the STD32 unit (which has already all the functions I need and is much more industrial product). Anyway, thanks for helping.