Thermistors Temperature or Frequency Conversion Circuit

Published:2011/8/1 0:27:00 Author:Michel | Keyword: Temperature, Frequency, Conversion Circuit | From:SeekIC

The picutre 3-6 is thermistor temperature or frequency conversion circuit.Because thermistors resistance changes with the temperature in linear way,the change can be used in voltage controlled oscillator.In the circuit,A1-A4 uses current type operational amplifier LM390O,RP1 and RP2 are used to adjust thermistors temperature-resistance properties and the voltage controlled oscillator voltage frequency characteristics.RP3 is used to regulate work range center of voltage controlled oscillator. Adjustment Process:When voltage controlled oscillator output voltage Ui is 7.5V and RP3are regulated,which makes output frequency f。 become 635Hz.lOkΩ calibrating resistance substitutes for thermistor RT and RP2 is regulated to make the output frequency f。 become 635Hz.Then 13·3kΩcalibrating resistance substitutes for thermistor RT again,RP1 is regulated to make the output frequency f。 become 143Hz.Please adjust like this for many times until the satisfying result is obtained.



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