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More than Circuit EngineeringHigh-accurate Measurement of Temperature (by the Nyquist Formula)
Ñõåìû >> Measurement >> High-accurate Measurement of Temperature (by the Nyquist Formula)High-accurate Measurement of Temperature (by the Nyquist Formula)
Through
the Circuit of high-accurate Thermometer (Pic.1) is possible to measure
temperature in a range from 260° Ñ to +2200° Ñ with the accuracy of measurement 0.1°
Ñ. Electro-motive Force (EMF) is determined by a Formula:
k – Boltzmann’s Constant
– Absolute Temperature of
Resistor;
– Frequency Band of Electro-motive Force
A1 – Active Band-pass Filter (Look Pic.1. High-accurate
Thermometer Circuit).
Pic.1.
High-accurate Thermometer Circuit.
(Measurement of Temperature in a
range from 260° Ñ to +2200° Ñ with the accuracy of measurement 0.1°
Ñ)
In the Input of Operational Amplifier À3 a Resistor R is applied. Resistor R has Square-law dependence Resistances from Voltage. That allows to get Line Voltage Uout. (Pic.1).
The Value of Resistors is calculated from formulas:
Resistor Square-law Characteristic can be get by using a Diode ÊÄ512.
Pic.2. Circuit of change VA Diode
Characteristic.
Pic. 3. Volt-ampere Diode
Characteristic.
Volt-ampere Diode Characteristic is not Square-law. But Calculating of Resistor R make possible to create VA Diode Square-law Characteristic.
added 18.07.07 01:02:51 | 
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