Sensors

As I am building a sensor networks I need sensors, I guess thinking about the sensors should be the first priority but my project is probably more about the network itself than the sensors, or more about the technology for making the measurements than the actual measurements:)

One thing I could think of for my sensor network was to use if for determining when our plants needs watering, hence I needed a moisture sensor.

I found a number of designs on the web which measured moisture by measuring the resistance between two metal rods (in a block of gypsum) placed in the soil:

http://www.cheapvegetablegardener.com/2009/11/how-to-make-cheap-soil-moisture-sensor-2.html

This design is very cheap so I might use if I decide to build many sensors but first I need to evaluate the Vegetronix VG400-LV.

http://www.vegetronix.com/Products/VG400/

The Vref for the A/D input for the Jeenode is 3.3V and the output from the VG400 is 0 - 1.8V, so the input signal should be handled by just connecting it directly to the Jeenode, although some if the precision is lost it should be acceptable for my purpose.