Multiple Temp Sensors

Hi,

I have read a few different threads on here and on other site discussing temp sensors, but as I am a complete novice I would like to ask not only a solution but also for some little guidance on what the solution means.

Arduino Uno is my board. Among other things I want to run 2 temperature sensors for measuring temps in 2 different locations.

I want to put the temp sensors on the end of at least 3m of lead length.

Some people have suggested that the temp sensors pick up noise on varying lead lengths and suggest to quieten the noise to put capacitors into the mix.

Can some one explain exactly where I would put the capacitors in (maybe a simple line drawing/schematic)

What would be the best sensor to work on a 3m lead length TMP35,LM35,DS18B20 etc or another type.

If you help, could you also explain a little on what the capacitor does within the above circuit design and what values would do etc

Thank you for helping.

The TMP35 and LM35 are analog. The value depends on the reference voltage of the Arduino. It means you can never be sure if that is an accurate temperature. Long wires could introduce some noise. Some sensors don't allow a capacitor, for others it is required with long wires.

The DS18B20 uses the OneWire bus. It is a digital temperature sensor and designed to be used with long wires (3 meters is no problem). Use a good library, and check if the data is valid. If you get valid data, you can be sure that the temperature is accurate. If you don't get valid data, just try again. A number of DS18B20 can be used on the same OneWire. I think that 10 sensors, each with 3 meters of wire, should be no problem.

OneWire start page : http://playground.arduino.cc/Learning/OneWire Paul Stoffregen maintains the library : http://www.pjrc.com/teensy/td_libs_OneWire.html The OneWire library has an example for the DS18B20. You don't need more. There is however a library that makes the use easier : http://milesburton.com/Main_Page?title=Dallas_Temperature_Control_Library

author=Peter_n link=msg=2321789 date=1437309593]

The OneWire library has an example for the DS18B20. You don’t need more. There is however a library that makes the use easier

You can hardly go wrong with the DS18B20, provided you work within its operating range -25 to 125. They are available with 3m and even 5m cable and plug for just a few dollars. If I recall correctly, the example in for them in the oneWire library must be about the worst programme ever written for Arduino. You will surely be better off here, a far more competent crowd who won’t mess you about.

http://www.hacktronics.com/Tutorials/arduino-1-wire-tutorial.html

they actually use the Miles Burton library alluded to above