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    Astable Multivibrator Using Ic741

    Uploaded by

    F.V. Jayasudha
    This document describes an experiment to generate a square wave using an IC 741 operational amplifier and a 555 timer IC in astable multivibrator mode. It includes the components required, the theory of operation explaining how a square wave is produced, diagrams of the circuit design, and procedures for constructing the circuit and measuring the output waveform frequency. The aim is to design an adjustable square wave oscillator and verify that the observed frequency matches the calculated theoretical frequency.

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    © All Rights Reserved
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    Astable Multivibrator Using Ic741

    Uploaded by

    F.V. Jayasudha
    295 views3 pages
    This document describes an experiment to generate a square wave using an IC 741 operational amplifier and a 555 timer IC in astable multivibrator mode. It includes the components required, the theory of operation explaining how a square wave is produced, diagrams of the circuit design, and procedures for constructing the circuit and measuring the output waveform frequency. The aim is to design an adjustable square wave oscillator and verify that the observed frequency matches the calculated theoretical frequency.

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    Original Title

    ASTABLE MULTIVIBRATOR USING IC741

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    This document describes an experiment to generate a square wave using an IC 741 operational amplifier and a 555 timer IC in astable multivibrator mode. It includes the components required, the theory of operation explaining how a square wave is produced, diagrams of the circuit design, and procedures for constructing the circuit and measuring the output waveform frequency. The aim is to design an adjustable square wave oscillator and verify that the observed frequency matches the calculated theoretical frequency.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    295 views3 pages

    Astable Multivibrator Using Ic741

    Uploaded by

    F.V. Jayasudha
    This document describes an experiment to generate a square wave using an IC 741 operational amplifier and a 555 timer IC in astable multivibrator mode. It includes the components required, the theory of operation explaining how a square wave is produced, diagrams of the circuit design, and procedures for constructing the circuit and measuring the output waveform frequency. The aim is to design an adjustable square wave oscillator and verify that the observed frequency matches the calculated theoretical frequency.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 3

    DEPARTMENT OF ECE SATHYABAMA

    Expt. No: 5
    Date ASTABLE MULTIVIBRATOR USING IC 741 and Timer IC 555
    AIM:
    To design a circuit to generate a Square Waveform of desired frequency using IC 741 and Timer IC 555 in
    Astable Multivibrator mode.

    APPARATUS REQUIRED

    Sl.No. Description Range / Number/ Value Qty

    1 Integrated Regulated Power Supply (ICPS) ±15 V 1

    2 Cathode Ray Oscilloscope (CRO) 20 / 40MHz, Dual Trace 1

    3 Operational Amplifier (OP-AMP) IC 741 1

    4 Resistor As per Design 5

    5 Capacitor 0.1µF 3

    6 Regulated Power Supply (0-30) V 1

    7 Timer IC IC 555 1

    8 Resistor 470 , 6.8 K , Each one


    10K 2

    9 Capacitor 470pF, 1Nf, 0.1µF Each one

    10 Bread board & Connecting wires

    THEORY:
    Square wave outputs are generated when the Op-Amp is forced to operated in the saturated region i.e. the
    output of the Op-Amp is forced to swing between positive saturation +V sat and negative saturation V sat
    resulting in a square wave output. This square wave generator is called a free running or Astable
    Multivibrator.The output of the Op-Amp in this circuit will be in the +ve and ve saturation depending on whether
    the differential voltage V id is +ve or ve respectively.In this circuit the Op-Amp runs from one quasi stable state
    to another on its own the output is a square wave whose frequency is determined by the RC combination. A

    Vsat or Vsat the output is also feedback to the input terminal after integrating by
    means of low pass RC combination. Whenever input at the ve terminal just exceeds V ref, switching takes
    place resulting in a square wave output.

    Feedback rate

    25
    DEPARTMENT OF ECE SATHYABAMA

    Total time period -

    The 555 timer is a highly stable device for generating accurate time delay or oscillations. It is a 8 pin IC
    that can be connected to external components for astable and monostable operations. Initially when the output
    is high C starts charging towards Vcc through Ra and Rb. As soon as the voltage across the capacitor equals 2/3
    Vcc, Comparator 1 triggers FF and the output switches low. Now C starts discharging through R b and transistor
    Q1. When Vc = 1/3 Vcc comparator 2 triggers FF and output goes high. Then the cycle repeats.
    The time during which the capacitor charges from 1/3 Vcc to 2/3Vcc is equal to the time, the output is high and
    is given by Tc = 0.69 (Ra + Rb)C
    Discharging time Td = 0.69Rb C
    Total time period of the output waveform
    T = Tc + Td = 0.69 (Ra + Rb)C.
    The 555 IC Timer: The 8-pin 555 timer IC is used in many projects, a popular version is the NE555. Most
    circuits will just specify '555 timer IC' and the NE555 is suitable for these. The 555 output (pin 3) can sink and
    source up to 200mA.
    To check the 555 IC timer the following procedure has to be followed. Apply 5V DC to
    pin no.8 and ground connection to pin no.1. Now the voltage at pin no. 5 will be 2/3 Vcc (3.3V)
    hence the Timer IC is in good condition otherwise the IC to be changed.

    CIRCUIT DIAGRAM:

    26
    DEPARTMENT OF ECE SATHYABAMA

    P
    ROCEDURE:

    1. Construct the circuit as per Circuit diagram shown in figure.


    2. Switch ON the RPS and CRO.
    3. Observe the Square Waveform at output pin of the IC and Ramp waveform across the capacitor.
    4. Verify the observed frequency with theoretical our calculated frequency
    5. Note the readings and draw the waveforms in Graph Sheet.

    TABULATION:

    Sl.No. Description R in ohms C in µF Theoretical Practical


    Frequency (HZ) Frequency

    1 IC 741

    2 IC 555

    RESULT:

    Thus the Square Wave Generator using IC 741 and IC 555 were constructed and waveform is traced.

    27

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