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[on:]

Hello Everyone,
This is my first project with arduino. I have some experience with Picaxe microcontrollers.

I was trying to develop a circuit that reads the temperature of the soil.
I am using a TMP36 sensor to do this. My question pertains to the circuit to get this result.
In other words, since the middle pin of the TMP36 reads temperature and the middle pin needs to be connected to analog pin of the arduino, how can I connect  another wire that touches the soil on one end and connects to the analog input pin on the other hand & then transmit the temp to the middle pin of the TMP36.

I hope my question makes sense and someone can give me some idea.

Thankyou.

[Reply #1 on:]

The TMP36 is the sensor.

Look at a datasheet here:
http://www.analog.com/static/imported-files/data_sheets/TMP35_36_37.pdf

I'll assume you have the T0-92 3 wire package.

I think you want Pin one to power.  Pin three to ground.  Pin two to analog in on the Arduino.  You are reading the change in the voltage on Pin 2 to get the temp.

You must have or there must be a conversion table.  This volt reading equals that temp.  Maybe you calibrate and make your own.  Don't know. 

If you are shoving it in the soil, you may need to pay attention to mounting it and protecting it. Don't know your application so can't speak to that.

[Reply #2 on:]

You can use a phone cord to connect to your sensor so your arduino doesn't have to be outside, but rather indoors. Take a look at this project I did. I have arduino and Phi-1 shield in my car and pass a 12ft phone cord to the back of my car to sense obstacles behind me.

http://liudr.wordpress.com/2011/02/12/arduino-parking-sensor/