Digital temperature sensor

Description.

Here is a straight forward, yet effective digital temperature controller that can be used with temperature control systems.

The circuit uses IC LM 35 (IC3) to as the temperature sensor. The output of LM 35 is given to the IC ADC 0804 (IC4) which converts the analog output of the LM 35 to digital output. The ADC 0804 is a 8 bit ADC. Eight LED’s are connected to the output  of ADC to show the output logic. If needed the LED’s can be avoided and the output can be connected to any suitable external circuit like temperature controller etc. A 5V fixed voltage regulator based on 7805 (IC1) powers the circuit. Another variable voltage regulator based on LM317 (IC2) is used to provide the reference voltage to the ADC 0804.

Circuit diagram with Parts list. 

Digital Temperature Sensor Circuit

Digital Temperature Sensor Circuit

Notes. 

  • POT R10 can be used to adjust the scale factor of the ADC.The reference voltage at pin  7 of ADC0804 should be 2.5 V for full scale.
  • Assemble the digital circuit project on a good quality PCB or common board.
  • If 1A bridge is not available make one with four 1N 4007 diodes.
Show Comments

29 thoughts on “Digital temperature sensor

  1. FIKADU DIRIBA

    thank u i am student pleace how i get the progeram of oil immersed distrubution transformer temperature sensor LM35 AND drive fan in micro c progeram

    Reply
  2. sathi

    i want connection for lm35 with adc0804 then that output given to encoder dow can i do this connection please help me

    Reply
  3. ganesh waysal

    hallo,
    i want to make temperature controller so please send me how to interface adc 0804 with 8051 using LM 35,and also send its ALP prgramming.
    i’m very thankful to you.

    Reply
  4. raj kumar sharma

    hi,
    i want to make aanalog to digital convertor with

    usb so i want your guide lines to make acircuit

    diagram .

    Reply
  5. sara

    hi sir
    please heeeeeeeeelllllppppppppppp meeeeeeeeeee
    I also need the detail of the component used after the bridge (AC 230V) It has the symbol of a transformer but i am not sure at all. please help me out.
    Thanks

    Reply
  6. sara

    I need the detail of the component used after the bridge (AC 230V) It has the symbol of a transformer but i am not sure at all. please help me out.
    Thanks

    Reply
  7. Neerav

    Hi i am actually using this circuit in my assignment. i am doing my circuit in Proteus. is there any need to connect pin8,10 and 20?
    I also need the detail of the component used after the bridge (AC 230V) It has the symbol of a transformer but i am not sure at all. please help me out.
    Thanks

    Reply
  8. seetharaman

    Hi Shaban and Vysakh please communicate in english such that others can also use your valuable information.

    Reply
    • jeni

      hello,plz help me,am working on this circuit,,plz send me the simulation of this circuit on proteus,,am very thank ful to you

      Reply
  9. erf

    plz put full description, I got problem in the simulation ?
    pin number 20 is connected to where? also 8 and 10 ? for pin number 7 need to connect to -2/5 or +2/5 ?
    i simulated in proteus but i can’t get the result plz describe it if is possible
    thanks alot

    Reply
  10. chandrashekar

    Its very good site for electronics persons and i like very much this site.

    Thanks for providing imformation

    Reply

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