i want to make soil moisture sensor....plz suggest me circuit diagram n abt probes....plz help

 

I've seen these for less than $4 at the local hardware store. Is there a reason you want to build your own?

 

yeah i hv to make a project n connect sprinkler to them ,.....so that v use optimum water required for plants

 

Here is an excellent link - http://www.cheapvegetablegardener.com/2009/03/how-to-make-cheap-soil-moisture-sensor.html

Get a cheapo DVM and switch between the soil probes.

 

why capaictance is prefred over resistance?????which one is cheap and accurate???

 

why capaictance is prefred over resistance????

Are you referring to relative humidity sensors? The soil moisture probes mentioned so far are resistive.

The worst thing about the homemade ones is that each one's response may be a bit different, so they may all need to be calibrated before really accurate usage.

 

Hello,

The wiki says that often capacitive sensors are used:
http://en.wikipedia.org/wiki/Soil_moisture_sensor

Bertus