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本文介绍一种以廉价晶体管做温度敏感元件,且适合于大批生产的电子温度计。这种仪表的特点是:从-50℃到+125℃温度范围内,测量精度为±0.1℃;通过1000天室温至125℃的温度循环试验,稳定度为±0.02℃;探头可以自由互换而使用者无须再作校准,工厂生产时也只用在一个温度下作出厂校准,而且是按新的低热质密封晶体管封装的。文中也介绍了理论分析和研制过程中所做的试验。且指出:如果晶体管的集电极电流是绝对温度的适当的二次函数,那么敏感元件晶体管的V_(be)几乎跟温度成线性变化。文章从理论上分析了各种电流函数对敏感元件晶体管V_(be)的线性度的影响,并与试验结果进行了比较。说明了求出最佳电流函数的方法,也介绍了电流函数发生器电路。文章还指出:若采用更贵的电流函数发生器并使敏感元件在三点作校准,则将达到±0.01℃的精度。文章还讨论了各种市场上买到的晶体管跟理论予测值的符合程度,也给出了晶体管的选择准则。
This article describes a low-cost transistor temperature-sensitive components, and suitable for mass production of electronic thermometers. This instrument is characterized by: from -50 ℃ to +125 ℃ temperature range, the measurement accuracy of ± 0.1 ℃; through 1000 days room temperature to 125 ℃ temperature cycling test, the stability of ± 0.02 ℃; probe can be freely swapped The user no longer need to calibrate, the factory production only with one factory calibration temperature, and is based on the new low thermal mass sealed transistor package. The article also introduces the theoretical analysis and testing in the development process. And pointed out: If the collector current of the transistor is a proper quadratic function of the absolute temperature, the V be of the transistor of the sensing element changes almost linearly with the temperature. In this paper, the influence of various current functions on the linearity of V_ (be) of the sensor transistor is theoretically analyzed and compared with the experimental results. Described the method to find the best current function, also introduced the current function generator circuit. The article also pointed out: If the use of more expensive current function generator and the sensor at three calibration points, it will reach ± 0.01 ℃ accuracy. The article also discusses the compatibility of various commercially available transistors with theoretical predictions, and gives the guidelines for transistor selection.