{"id":1345,"date":"2014-02-01T01:17:17","date_gmt":"2014-02-01T07:17:17","guid":{"rendered":"http:\/\/fortmarinus.com\/blog\/?p=1345"},"modified":"2014-06-28T20:43:04","modified_gmt":"2014-06-29T01:43:04","slug":"how-to-measure-temperature-with-a-thermistor","status":"publish","type":"post","link":"http:\/\/fortmarinus.com\/blog\/1345\/","title":{"rendered":"How to Measure Temperature with a Thermistor"},"content":{"rendered":"<p>An NTC (Negative Temperature Coefficient) Thermistor is a passive electrical component whose resistance varies inversely with temperature.<sup><a href=\"#footnote_0_1345\" id=\"identifier_0_1345\" class=\"footnote-link footnote-identifier-link\" title=\"Wikipedia &amp;#8220;Thermistor&amp;#8221;\">i<\/a><\/sup> It is often used as a temperature sensor. The relationship between resistance and temperature can be described with the &#8216;beta&#8217; formula.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" src=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/NTC-thermistor-symbol.png\" alt=\"\" title=\"NTC-thermistor-symbol\" width=\"150\" height=\"100\" class=\"aligncenter size-full wp-image-1398\" \/><\/P><\/p>\n<p>In this experiment we will show how to use the National Instruments myDAQ<sup><a href=\"#footnote_1_1345\" id=\"identifier_1_1345\" class=\"footnote-link footnote-identifier-link\" title=\"National Instruments &amp;#8220;myDAQ Portable Measurement and Instrumentation Device&amp;#8221;\">ii<\/a><\/sup> in conjunction with LabVIEW<sup><a href=\"#footnote_2_1345\" id=\"identifier_2_1345\" class=\"footnote-link footnote-identifier-link\" title=\"\">iii<\/a><\/sup> to create a Virtual Instrument that automatically and continuously measures the temperature. It is noted, however, that myDAQ\/LabVIEW are not needed for the simplest form of this exercise, which can be performed with just a multimeter and a thermistor. <\/p>\n<p style=\"text-align: center;\"><span style=\"color: #9c8a6a;\">_______________________________________________________________________________________<\/span><\/p>\n<h3><strong>Parts List<\/strong><\/h3>\n<ul>\n<li>1x National Instruments myDAQ (using the DMM ohmmeter probes)<\/li>\n<li>1x LabVIEW software<\/li>\n<li>1x 10K\u03a9 Thermistor (ex: Vishay NTCLE100E3  from Digikey BC2396CT-ND)<sup><a href=\"#footnote_3_1345\" id=\"identifier_3_1345\" class=\"footnote-link footnote-identifier-link\" title=\"\">iv<\/a><\/sup> <\/li>\n<li>2x pieces of wire (or probes)<\/li>\n<li>1x (optional) MyProtoboard<sup><a href=\"#footnote_4_1345\" id=\"identifier_4_1345\" class=\"footnote-link footnote-identifier-link\" title=\"\">v<\/a><\/sup> (or any breadboard) <\/li>\n<\/ul>\n<h3><strong>Equations<\/strong><\/h3>\n<p>The relationship between resistance and temperature is given by the &#8216;beta&#8217; equation<sup><a href=\"#footnote_5_1345\" id=\"identifier_5_1345\" class=\"footnote-link footnote-identifier-link\" title=\"NTC Thermistors &amp;#8220;Engineering Notes from Spectrum Sensors and Controls Inc. via Digikey Corp.&amp;#8221;\">vi<\/a><\/sup>, a simplified approximation of the Steinhart-Hart equation.<sup><a href=\"#footnote_6_1345\" id=\"identifier_6_1345\" class=\"footnote-link footnote-identifier-link\" title=\"Wikipedia &amp;#8220;Steinhart&ndash;Hart equation&amp;#8221;\">vii<\/a><\/sup> The Beta value (B), the Reference Temperature (T0), and the Reference Resistance (R0) are given in the thermistor&#8217;s datasheet<sup><a href=\"#footnote_7_1345\" id=\"identifier_7_1345\" class=\"footnote-link footnote-identifier-link\" title=\"Vishay BCcomponents &amp;#8220;NTCLE100E3\n NTC Thermistors, Radial Leaded, Standard Precision&amp;#8221;\">viii<\/a><\/sup>. The component&#8217;s Resistance (R) is measured by an ohmmeter and then Temperature (T) can be solved for. <\/p>\n<p style=\"text-align: center;\">The &#8216;Beta&#8217; Equation:<\/P><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #000000;\"><img src='http:\/\/s.wordpress.com\/latex.php?latex=B%20%3D%20%5Cfrac%7BT_%7B0%7D%5Ccdot%20T%7D%7BT-T_%7B0%7D%7D%5Ccdot%20ln%5Cleft%20%28%20%5Cfrac%7BR_%7B0%7D%7D%7BR%7D%20%5Cright%20%29&#038;bg=ffffff&#038;fg=9C8A6A&#038;s=2' alt='B = \\frac{T_{0}\\cdot T}{T-T_{0}}\\cdot ln\\left ( \\frac{R_{0}}{R} \\right )' title='B = \\frac{T_{0}\\cdot T}{T-T_{0}}\\cdot ln\\left ( \\frac{R_{0}}{R} \\right )' class='latex' \/><\/span><\/p>\n<p style=\"text-align: center;\">Solving for T,<\/P><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #000000;\"><img src='http:\/\/s.wordpress.com\/latex.php?latex=T%20%3D%20%5Cfrac%7BB%7D%7Bln%20%5Cbig%28%20%5Cfrac%7B%20R%20e%5E%7B%20%5Cfrac%7BB%7D%7BT_%7B0%7D%7D%20%7D%20%7D%7BR_%7B0%7D%7D%20%5Cbig%29%7D&#038;bg=ffffff&#038;fg=9C8A6A&#038;s=2' alt='T = \\frac{B}{ln \\big( \\frac{ R e^{ \\frac{B}{T_{0}} } }{R_{0}} \\big)}' title='T = \\frac{B}{ln \\big( \\frac{ R e^{ \\frac{B}{T_{0}} } }{R_{0}} \\big)}' class='latex' \/><\/span><\/p>\n<h3><strong>&#8216;Circuit&#8217; Setup<\/strong><\/h3>\n<p>Simply attach the myDAQ ohmmeter probes to the thermistor which can be placed optionally onto the breadboard. The resistance will be measured by the myDAQ and sent to LabVIEW for processing.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" src=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorCircuitPhoto.jpg\" alt=\"\" title=\"ThermistorCircuitPhoto\" width=\"400\" height=\"400\" class=\"aligncenter size-full wp-image-1375\" srcset=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorCircuitPhoto.jpg 992w, http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorCircuitPhoto-150x150.jpg 150w, http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorCircuitPhoto-300x300.jpg 300w\" sizes=\"(max-width: 400px) 100vw, 400px\" \/><\/p>\n<p>&nbsp;<br \/>\n&nbsp;<\/p>\n<h3><strong>LabVIEW Front Panel<\/strong><\/h3>\n<p>The Virtual Instrument Front Panel allows the user to input the Beta Value, the Reference temperature, and the Reference Resistance, again taken from the Datasheet. The resistance measured by the myDAQ is also displayed. The interface graphically outputs the calculated temperature in Kelvin, Celsius, and Fahrenheit. <\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" src=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorLabViewPanelScreenshot.jpg\" alt=\"\" title=\"ThermistorLabViewPanelScreenshot\" width=\"470\" height=\"542\" class=\"aligncenter size-full wp-image-1377\" srcset=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorLabViewPanelScreenshot.jpg 470w, http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorLabViewPanelScreenshot-260x300.jpg 260w\" sizes=\"(max-width: 470px) 100vw, 470px\" \/><\/P><br \/>\n&nbsp;<br \/>\n&nbsp;<\/p>\n<h3><strong>LabVIEW Block Diagram<\/strong><\/h3>\n<p>The block diagram is the programming language of LabVIEW and the back-end of the Front Panel. Each component on the Front Panel is graphically represented in the block diagram. The image shows how the variable inputs from the front panel and the myDAQ are passed through a graphical representation of the beta formula and then output as temperature values.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" src=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorLabViewBlockScreenshot.jpg\" alt=\"\" title=\"ThermistorLabViewBlockScreenshot\" width=\"945\" height=\"720\" class=\"aligncenter size-full wp-image-1378\" srcset=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorLabViewBlockScreenshot.jpg 945w, http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorLabViewBlockScreenshot-300x228.jpg 300w\" sizes=\"(max-width: 945px) 100vw, 945px\" \/><\/p>\n<p>&nbsp;<br \/>\n&nbsp;<\/p>\n<h3><strong>Excel Calculator<\/strong><\/h3>\n<p>If myDAQ and LabVIEW are not available, Excel can be used to calculate the temperature. <\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" src=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorCalculatorScreenshot.jpg\" alt=\"\" title=\"ThermistorCalculatorScreenshot\" width=\"810\" height=\"758\" class=\"aligncenter size-full wp-image-1379\" srcset=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorCalculatorScreenshot.jpg 810w, http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorCalculatorScreenshot-300x280.jpg 300w\" sizes=\"(max-width: 810px) 100vw, 810px\" \/><\/p>\n<p>&nbsp;<br \/>\n&nbsp;<\/p>\n<h3><strong>Findings<\/strong><\/h3>\n<p>In this experiment, we measured the temperature under the following scenarios: room temperature, surrounding the thermistor with a bag of ice, and grasping it while blowing hot breath on it.  Indeed, the thermistor&#8217;s resistance is inversely related to temperature. This is a relatively easy experiment that can serve as a good introduction to circuit elements, data acquisition, and LabVIEW programming. Enjoy!<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" src=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorScenarioFindings.jpg\" alt=\"\" title=\"ThermistorScenarioFindings\" width=\"501\" height=\"289\" class=\"aligncenter size-full wp-image-1380\" srcset=\"http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorScenarioFindings.jpg 501w, http:\/\/fortmarinus.com\/blog\/wp-content\/uploads\/2014\/02\/ThermistorScenarioFindings-300x173.jpg 300w\" sizes=\"(max-width: 501px) 100vw, 501px\" \/><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #9c8a6a;\">_______________________________________________________________________________________<\/span><\/p>\n<h3><strong>Downloads<\/strong><\/h3>\n<p><a title=\"Marinus' National Instruments LabVIEW Thermistor Calculator Virtual Instrument\" href=\"http:\/\/www.fortmarinus.com\/downloads\/Thermistor%20Temperature%20Calculator.vi\"  target=\"_blank\">Marinus&#8217; National Instruments LabVIEW Thermistor Calculator Virtual Instrument<\/a> <\/strong>(v1.0) 2014 01 31<br \/>\n<a title=\"Marinus' Thermistor Temperature Calculator in Excel\" href=\"http:\/\/www.fortmarinus.com\/downloads\/FortMarinus%20Electronics%20Calculator.xlsm\"  target=\"_blank\">Marinus&#8217; Thermistor Temperature Calculator in Excel<\/a> <\/strong>(v1.0) 2014 01 31<\/p>\n<p style=\"text-align: center;\"><span style=\"color: #9c8a6a;\">_______________________________________________________________________________________<\/span><\/p>\n<p>&nbsp;<br \/>\n&nbsp;<\/p>\nReferences:<ol class=\"footnotes\"><li id=\"footnote_0_1345\" class=\"footnote\"><a href=\"http:\/\/en.wikipedia.org\/wiki\/Thermistor\" onclick=\"javascript:_gaq.push(['_trackEvent','outbound-article','http:\/\/en.wikipedia.org']);\" target=\"_blank\">Wikipedia<\/a> &#8220;Thermistor&#8221; [<a href=\"#identifier_0_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><li id=\"footnote_1_1345\" class=\"footnote\"><a href=\"http:\/\/sine.ni.com\/nips\/cds\/view\/p\/lang\/en\/nid\/210929\"  target=\"_blank\">National Instruments<\/a> &#8220;myDAQ Portable Measurement and Instrumentation Device&#8221; [<a href=\"#identifier_1_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><li id=\"footnote_2_1345\" class=\"footnote\"><a href=http:\/\/www.ni.com\/labview\/\"  target=\"_blank\">National Instruments<\/a> &#8220;LabVIEW System Design Software&#8221; [<a href=\"#identifier_2_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><li id=\"footnote_3_1345\" class=\"footnote\"><a href=http:\/\/www.digikey.com\/product-detail\/en\/NTCLE100E3103JT2\/BC2396TR-ND\/2230724\"  target=\"_blank\">NTC Thermistor<\/a> &#8220;Digi-Key BC2396TR-ND&#8221; [<a href=\"#identifier_3_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><li id=\"footnote_4_1345\" class=\"footnote\"><a href=http:\/\/sine.ni.com\/nips\/cds\/view\/p\/lang\/en\/nid\/210925\"  target=\"_blank\">MyProtoboard<\/a> &#8220;Protoboard Kit by Elenco for myDAQ via National Instruments&#8221; [<a href=\"#identifier_4_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><li id=\"footnote_5_1345\" class=\"footnote\"><a href=\"http:\/\/www.digikey.com\/Web%20Export\/Supplier%20Content\/api-technologies-1171\/pdf\/api-ntc-engineering-notes.pdf?redirected=1\"  target=\"_blank\">NTC Thermistors<\/a> &#8220;Engineering Notes from Spectrum Sensors and Controls Inc. via Digikey Corp.&#8221; [<a href=\"#identifier_5_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><li id=\"footnote_6_1345\" class=\"footnote\"><a href=\"http:\/\/en.wikipedia.org\/wiki\/Steinhart%E2%80%93Hart_equation\"  target=\"_blank\">Wikipedia<\/a> &#8220;Steinhart\u2013Hart equation&#8221; [<a href=\"#identifier_6_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><li id=\"footnote_7_1345\" class=\"footnote\"><a href=\"http:\/\/www.vishay.com\/docs\/29049\/ntcle100.pdf\"  target=\"_blank\">Vishay BCcomponents<\/a> &#8220;NTCLE100E3<br \/>\n NTC Thermistors, Radial Leaded, Standard Precision&#8221; [<a href=\"#identifier_7_1345\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><\/ol>","protected":false},"excerpt":{"rendered":"<p>An NTC (Negative Temperature Coefficient) Thermistor is a passive electrical component whose resistance varies inversely with temperature.i It is often used as a temperature sensor. The relationship between resistance and temperature can be described with the &#8216;beta&#8217; formula. In this experiment we will show how to use the National Instruments myDAQii in conjunction with LabVIEWiii [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[32,9],"tags":[36,42,34,33,37,35],"_links":{"self":[{"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/posts\/1345"}],"collection":[{"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/comments?post=1345"}],"version-history":[{"count":65,"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/posts\/1345\/revisions"}],"predecessor-version":[{"id":1440,"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/posts\/1345\/revisions\/1440"}],"wp:attachment":[{"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/media?parent=1345"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/categories?post=1345"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/fortmarinus.com\/blog\/wp-json\/wp\/v2\/tags?post=1345"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}