菜单
  

    by  a nominal  temperature coefficient a = (385k2)10-5  "C'.
    With  an excitation current  of 373 pA  and a total
    differential subtraction gain of  68.2 V/V, a  sensitivity of
    +)(cc
    10 pV/mK has been  obtained at  the measurement circuit
    output  (voltage  Vhem  in  Figg.  1  and  2).  The  output
    voltage from the measurement circuit of Fig. 2 is sent to
    an A/D converter (Harris,  ICL7129) which then drives a
    liquid  crystal display  (Varitronix, BD503DP) with  4%
    digits.  An  analog  voltage is also available  at  a  BNC
    output  connector on  the  back  of  the  thermometer case.
    Due  to  the kinds of A/D  converter and display that have
    been  adopted,  the theoretical  resolution  of  the  digital
    measurements  turns  out  to be 1 mK  or 10 mK  in  the
    temperature intervals of 320 "C or +200 "C,  respectively.
    The  desired measurement range can  be  selected  by  a
    manual switch  acting on  the  A/D  converter  and on  the
    dynamic of  the display (SO0 mV or +2 V,  respectively).
    Calibration  of  the instrument offset  and gain is  made
    possible by  means  of  the Rwl and  Rw2 potentiometers,
    respectively.  The  power  supply  consists  of  two  9-V
    batteries which are connected in series. Owing to  the low-
    power consumption of  the adopted electronic circuit, the
    power supply  allows for  a  continuous  operation of  the
    thermometer for a period longer than 100 hours.
    A picture of the entire instrument and sensor is shown
    in Fig. 3.  This  thermometer has been  developed mostly
    for near-room-temperature operation and it is specifically
    designed for thermoelectronic control loops aimed at the
    temperature  stabilization of  small  optical or mechanical
    parts  even  out side  of  the laboratory  environment.
    Henceforth, the device is portable and battery operated.
    loop topology  is  now  becoming  widely used  for
    temperature measurements using  resistive sensors. When
    compared  to  a  standard bridge circuit, the Anderson's
    loop  also presents the clear advantage  of  generating an
    output voltage  which varies;  linearly with the sensor
    resistance. If  a perfectly linear and calibrated electronic
    circuit  is  developed, the remaining measurement errors
    then arise from the sensor non-linearity and from the
    aging of both the sensor and the electronic circuit.
    In this paper the design and performance of a compact
    and accurate digital thermometer, with a 4%  digit display,
    is  described. The  thermometer  uses  a four-lead  Pt-100
    commercial temperature transducer sensed  by  a  doubly
    differential subtraction  circlcit  in  an  Anderson's  loop
    configuration. The combination of a low-noise electronics
    and a careful instrument calibration  allows  for  accurate
    temperature measurements  in  a  e00  OC  interval withm
    the operating range of the sensor.
    2. Digital Thermometer Design
    The  thermometer design  is based  on  a  current  loop
    excitation acting on  a  resistive  thermal  sensor whereas
    active doubly differential  subtraction is used  to  read  the
  1. 上一篇:甲基叔丁基醚MTBE英文文献和翻译
  2. 下一篇:LabVIEW外文文献和翻译
  1. 汽车乘员舱的声振耦合英文文献和中文翻译

  2. 立体光照成型的注塑模具...

  3. 数控机床英文文献和中文翻译

  4. 工业机械手英文文献和中文翻译

  5. 低频振动的铁路车轴的状...

  6. 接头的形状对沥青塞接头...

  7. 数控加工技术英文文献和中文翻译

  8. 杂拟谷盗体内共生菌沃尔...

  9. java+mysql车辆管理系统的设计+源代码

  10. 十二层带中心支撑钢结构...

  11. 电站锅炉暖风器设计任务书

  12. 酸性水汽提装置总汽提塔设计+CAD图纸

  13. 大众媒体对公共政策制定的影响

  14. 当代大学生慈善意识研究+文献综述

  15. 河岸冲刷和泥沙淤积的监测国内外研究现状

  16. 乳业同业并购式全产业链...

  17. 中考体育项目与体育教学合理结合的研究

  

About

751论文网手机版...

主页:http://www.751com.cn

关闭返回