Electronic thermometer

Posted on Feb 5, 2014

This very simple circuit is an electronic thermometer using an inexpensive silicon transistor (2N2222) as the temperature sensor or probe. The circuit provides better than 1ƒ accuracy over a 100ƒ range. An LM113 diode regulates the input voltage to 1. 2 V. The 1. 2 / is applied through R2 to set the operating current of the temperatu

Electronic thermometer
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re-sensing 2N2222. R4 biases the amplifier output for zero output at 0ƒ, while feedback resistor R5 calibrates the output scale factor to 100 mV/ƒ. Once the output is zeroed, the scale factor does not change the zero. National Semiconductor Linear Applications Handbook 1991, p 171.

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