Quartz thermometer

<p>The quartz thermometer is a high-precision, high accuracy temperature sensor. It measures temperature by measuring the frequency of a <a href="/facts/Crystal_oscillator/QhhohzPu">quartz crystal oscillator</a>. The oscillator contains a specially cut crystal that results in a linear temperature coefficient of frequency, so the measurement of the temperature is essentially reduced to measurement of the oscillator frequency. Resolutions of .0001 °C, and accuracy of .02 °C from 0-100 °C are achievable. The high linearity makes it possible to achieve high accuracy over an important temperature range that contains only one convenient temperature reference point for calibration, the <a href="/facts/Triple_point/Npary634">triple point of water</a>.
</p><p>Introduced by <a href="/facts/Hewlett-Packard/abuNSYNu">Hewlett-Packard</a> in 1965, the successor company, <a href="/facts/Agilent/wKJ8cvAc">Agilent</a>, has discontinued the Model 2804A Quartz Thermometer.
Other manufacturers make nearly linear-in-temperature quartz crystals that may be used to construct thermometers of similar performance.
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<ul><li><a href="http://www.hparchive.com/Journals/HPJ-1965-03.pdf">original announcement</a></li>
<li><a href="https://www.keysight.com/en/pd-2804A%3Aepsg%3Apro-pn-2804A/quartz-thermometer?cc=US&lc=eng">2804A Quartz Thermometer discontinued</a> - last version of the manual, available here, is dated 1986</li>
<li><a href="https://web.archive.org/web/20101130042739/http://statek.com/products/pdf/10162.pdf">Quartz temperature sensors</a> - linear crystals for making thermometers</li></ul>

Quartz thermometer open-in-new

Quartz thermometer