hello everybody
i want some help about how to transport the output signal of the LM35
to a microcontroller which is 10 to 13m away from the sensor what should i do, and i need a design for an amplifier to the signal

 

How were you planning to make the connection? And what is the input impedance of the microcontroller's A to D?

 

You should go to National's website and download their datasheet for the LM35.

Check out the Applications section. One application deals with using an ADC IC near the LM35 to digitize the signal early, before noise gets on the analog output.

I would not suggest trying to amplify the LM35 output, nor running it for long distances.

 

http://www.omega.com/literature/transactions/volume2/analogsignal2.html

Convert the signal to a proportional 4-20ma one way it can be done.

Another is to use an ADC and a communications circuit to transmit the data. There are many ways to do it.