[TriEmbed] Fw: Raspberry Pi & remote temp sensor

[John Vaughters]

On , John Vaughters <jvaughters04 at yahoo.com> wrote:
 
I am a big fan of 10k Thermistors. They are SUPER cheap and have a decent temp range to. They require an analog input but basically you use them with another 10K regular resistor as a voltage divider. I have used them to measure room temperature and Coolant temperature on a car to operate an electirc fan. I ran wire about 10 feet long, but you could run it much much longer. All you would have to do is compensate the resistance into the calulation. But I doubt you would have to at all except for very long distances. In any case you always want to calibrate any temp reading if you need true accuracy. This can be done with software or resistance trimming. 

Here is the calculation code and other use information.

Arduino Playground - Thermistor2

 
 Arduino Playground - Thermistor2
/*  * Inputs ADC Value from Thermistor and outputs Temperature in Celsius  *  requires: include <math.h>  * Utilizes the Steinhart-Hart Thermistor Equation:   
View on playground.arduino.cc Preview by Yahoo  
 
John Vaughters
On Friday, May 2, 2014 9:27 PM, Terry King <terry at terryking.us> wrote:
 
Hi,

There is a lot about this temperature sensor on the ArduinoInfo.Info WIKI here:
http://arduino-info.wikispaces.com/Brick-Temperature-DS18B20

On that page you'll see a link to the  "MAXIM Application note about Long Cables"

Net: 50 feet or so no problem... Many people run 100+ feet using CAT5 cable.

Regards, Terry King
...In The Woods in Vermont, USA
terry at yourduino.com

---------------------( COPY )---------------------
Not sure about the 1-wire.  I have some DHT22 / AM2302 (one signal wire,
but not "1-wire" protocol) running about 16 meters on wire that was once
used for security system sensors.  Hooked to an Arduino right now, but they
worked similarly on a Raspberry Pi before I used that for another project.


On Fri, May 2, 2014 at 4:06 PM, Grawburg <grawburg at myglnc.com> wrote:

> I have an RPi set up with two DS18B20 temperature sensors - one is fixed
> on a breadboard and one is the waterproof unit with about a meter
> extension (got from AdaFruit).  Works fine as is. I do not need a
> waterproof sensor but would like to put the sensor 10 to 15 feet away from
> the RPi: we are measuring the temperature at different points in a room.
>  What's the reasonable limit for extending the sensor away from the Pi?
>
>
> Thanks,
> Brian Grawburg
>
> --
> I will no longer use Mozilla/Firefox. I now use Opera Web Browser.
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Regards, Terry King
...In the Woods in Vermont USA
terry at terryking.us

-The One who Dies with the most Parts LOSES. What do you need??



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