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    With this simple temperature to voltage converter circuit we can do a precise measurement of the temperature in a room. A NTC resistor or a thermistor is used as a sensor that has a strong temperature dependence.
    If the NTC temperature rises then the output voltage rises with 0.5 V per 10C.

    Conversion factor depends on the type of thermistor resistance used. If you want to read the temperature directly on an universal measurement device then the value of R9 must be choosed so that the desired sensitivity is achieved (R8 must be equal with R9).
    The power supply voltage level is not critical; D1 zener voltage can be between 4.7 V and 8.2 V. The current consumption is about 12 mA.

    Temperature-Voltage Converter Circuit Diagram

    temperature voltage converter circuit diagram

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    18 Responses to "Temperature to Voltage Converter Circuit"

    1. RE: High School Science projects;
      We do an annual project using chemical reactions to run small motors powering toy cars. These reactions tend to be .9-1.3v @ 1ma. Is there an easy method of increasing the outputs to power the cars?

      • ROHAIL KHAN says: on March 25, 2012 at 11:24 am

        ya
        connect to the output common collector amplifier output power will be increased.
        by ROHAIL KHAN

        ;

    2. Sir,can you please provide me the exact operation of the circuit temperature to voltage converter

    3. can you please provide me the exact operation of circuit temperature to voltage converter with report

      • Jim Keith Jim Keith says: on July 24, 2012 at 1:33 pm

        The 4 resistors (including pot) on the left side form a resistance bridge circuit.
        The 470Ω resistor and zener form a shunt voltage regulator to minimize the influence of variations in the 12V power supply.
        The operational amplifier and the remaining resistors make up a classic differential amplifier that measures the voltage difference between the mid-points of the bridge.
        Virtually any operational amplifier may be used.

    4. how many watt require to heat a pipe of 1-1.5 inches dia 230 V HEATING LENGTH 2ft temp. 160-200 c

      • Jim Keith Jim Keith says: on July 24, 2012 at 1:19 pm

        Use the rule of thumb:
        Temp Rise = 1.24mW/°C/cm²
        This provides an estimation for temp rise in the order of 50 to 100°C. For higher temperatures, there is more radiation cooling, so it will take more power–perhaps double. Hope this helps

      • Jim Keith Jim Keith says: on July 24, 2012 at 1:40 pm

        for convection cooling

    5. what is the capacitor action in the above circuit……? How does the capacitors act?

    6. The 1nF capacitor provides frequency compensation for the op amp to prevent oscillation. Most op amps have an internal capacitor for this function.

      The 100nF capacitor slows down the response of the circuit. The RC time constant = 680K * 100nF = 68mS. Fast response is unnecessary because temperature variations are generally very slow.

      • DEar sir,
        Please tell me in the upper circuit what is the symbol (with values 6.8V n 400mW)on the left is for?
        seeing it 4 the first time…
        Thnx.

    7. Oghenejabor says: on November 6, 2012 at 8:41 am

      Please sir, I am having difficultly in replacing a Burt transformer in a circuit board. The capacitor connected to it is 25v/100uf

    8. rohail khan says: on November 11, 2012 at 11:29 am

      DEAR SIR,
      Will u send me notes of a differential amplifier with mathematical calculation???

    9. This is a 6.8V zener diode–it is required to provide voltage stability so that changes in voltage (as the 12V battery discharges) do not appear as changes in temperature.

    10. Would I be able to control the temperature of a heating tray? This consists of a shallow closed in metal box about 3cm deep and about 50 cm long and 30 cm wide. Inside is a resistance coil of about 350 Ohms. The power supply is 220 VAC. I want to be able to melt material in a metal bowl on the tray with the proviso that the temperature of the melted material stays at approximate 30 C.

    11. Abhijith says: on January 5, 2014 at 1:15 pm

      Sir,what will be the maximum possible range of temperature that will be effectively converted to voltage and ensure safety of the circuit

    12. input voltage is 12,output is around 10?right?

    13. Tilahun says: on June 20, 2014 at 8:51 am

      sir could you explain the possibilty of any type of heat can be converted in to requred voltage ? if is possible how about temprature from hot gas?

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