Voltage into Frequency Converter Circuit using 741 IC

IC 741 is the most used and popular operational amplifier IC, because of its unique feature and low price. Various op-amp 741-based projects are already posted in the operational amplifier-based projects section. Now, here is a simple project using a couple of op-amps 741 IC called voltage into frequency converter.

Description of voltage into frequency converter Circuit using 741 IC

The circuit of voltage into frequency converter consists of a couple of op-amp 741, a couple of transistors, and a few passive components (resistors). The voltage of 0.5V to 15V is given to Vin pin 2 of IC1 through VR1 and resistor R1 and is converted to its corresponding frequency. This circuit posted here can also be used as voltage measurement in digital form.

circuit diagram of voltage into frequency converter

IC1 is configured in inverter mode and IC2 in Schmit trigger mode. The output of IC1 is dependent on input voltage and is given to the input of IC2. IC2 becomes ON and OFF in fixed time intervals. The triangle wave is obtained at the output of IC2. A Triangle wave is further amplified and changed into a square wave by two transistors T1 and T2. This square wave is given to counter roe reading.

PARTS LIST OF VOLTAGE TO FREQUENCY CONVERTER CIRCUIT USING 741 IC

Resistor (all ¼-watt, ± 5% Carbon)

R1 = 1 MΩ

R2 = 18 KΩ

R3 = 10 KΩ

R4 = 220 KΩ

R5 = 100 KΩ

R6 = 2.2 KΩ

R7 = 2.7 KΩ

R8 = 10 KΩ

R9 = 12 KΩ

VR1 = 500 KΩ

VR2 = 5 KΩ

 Capacitor

 C1 = 0.1 µF (Ceramic Disc)

Semiconductors

IC1, IC2 = 741 (General Purpose Operational Amplifier)

D1 = 1N34 (Germanium Diode)

T1, T2 = BC108 (general purpose low power Silicon NPN bipolar junction transistors )

24 Thoughts to “Voltage into Frequency Converter Circuit using 741 IC”

  1. BHANU PRAKASH

    TELL ME THE CAPACITANCE OF C1 CAPACITOR

    1. Thank you for recalling, I have updated the value of capacitor c1

  2. BHANU PRAKASH

    please tell me where exactly the input is given either 2nd or 3rd terminal of first IC and tell me about the 4th terminal in second IC

  3. Pin 2 2 and 3 of IC1 is connected as shown in circuit diagram and pin 4 of IC2 is zero potential pin which is not necessary to connect.

    1. Muzamil

      Can i use fixed resistor instead of variable resistors used above

      1. You most have to use variable resistor.

  4. Mahdieh

    hello
    what is vin? pulse or dc

  5. khan

    i want to know how to check frequency at output

      1. aditya thota

        sir can i know complete project details of under and over voltage indicator with op amp window comparator

  6. Ta

    i think the square wave should be obtained at the output of 2nd IC itself as it is in Schmitt Trigger mode, the transistors ahead just amplify it.

  7. somasundaram

    my simulation of the above circuit is not coming correct in multisim

  8. rakshith

    what is the formula to calculate frequency theoreticaly

  9. talha saeed

    sir,telll us the use of frequency converter and its advantage
    why we need frequency converter.

  10. talha

    what will be output of voltage into frequency converter by lm 741 ic?

  11. Tejaswini

    How to calculate the theatrical frequency?

  12. supreetha m s

    How to get the output for voltage to frequency converter?

  13. Bawya Mayuranathan

    is it easy to design the ciruit

  14. Bawya Mayuranathan

    i am 2nd year student our group has joined to do a small project.please recommend some of the small and simple projects

  15. shivanagesh

    how to measure the output frequency?

  16. Uday

    will u please upload video of above expt

  17. Uday

    plz upload video

  18. Imran

    Sir, where should I get the output and what is the formula for frequency. I did transient analysis but it was dc

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