BioBoard/Documentation/Temperature: Difference between revisions

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=Introduction to temperature=
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=Building a thermometer=
 
==Digital thermometer==
 
===What you need===
 
===How to build it===
 
===Things to keep in mind===
 
==Thermistor==
A thermistor is a type of resistor which has a very well known dependence of the resistance on temperature, and the change is quite steep so that we can resolve small differences in temperature. We are using them in place of thermometers, and they are sometimes referred to a "resistance thermometers" - they are inexpensive, easy to find, and are '''very''' easy to interface to the Arduino.  They are specified mainly by their room temperature (25 C) resistance and a common value is 10 kOhms. If many models are available, like from a major electronics supply house, you can also specify the tolerance and you can choose from different shapes and sizes (the size of a match head is good for starters).  As well, there are two general types of thermistors - ones that increase in resistance with increasing temperature (PTC) and those that decrease in temperature with increasing temperature (NTC).
===What you need===
Besides your Arduino, all you need is a standard resistor with a value that is the same as the room temperature resistance of your thermistor.  You'll be building a "voltage divider" so that you can use the 5 VDC output of the Arduino and have good resolution over the full temperature range of the thermistor (usually something like -40 C to +125 C, perfect for biological experiments).  For our examples we'll be using a 10 kOhm NTC thermistor (Sparkfun and Hacktronics carry these) with a 10 kOhm resistor for the bridge.
===How to build it===
 
===Things to keep in mind===
 
=Interfacing and measuring=
 
=Calibrating a home-built thermometer=
 
=Making it cooler=
 
=Geeking out=
 
=Links=

Latest revision as of 08:19, 30 September 2016

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