# Last edited on 2017-02-07 05:57:47 by jstolfi

DIGITAL THERMOMETERS

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2017-01-02

  Had bought two digital aquarium thermometers from Banggood.
  The digital display has 0.1 C precision.  The sensing element
  is a chrome-plated (??) metal cylindrical capsule ~4 mm diameter, 
  closed at bottom, with an insulated wire coming out from the
  top, sealed with some black material.
  
  For near ambient temperature, they seemed to match the analog 
  thermometer (Incotherm).
  
  Tested them by placing the sensors, taped together above the
  capsule, in an ice bath. The wires too were immersed for the last ~5
  cm.
  
  The displays show 1.5--2.0 C when the analog thermometer shows 0 C
  exactly. Only when pressed against the ice they would show 0.1--0.2 C.
  
  Presumably the electronic sensor (resistor or transistor) inside
  the capsule generates some heat by itself.