Integrator and Differentiator using IC 741 OpAmp
Prerequisite: Know the theory about the experiment. Study the pin diagram and functioning of each pin of IC 741. Study how an integrator and a differentiator work.
Objective: To study the working of opamp as differentiator and integrator.
Apparatus:
Bread board  1 
Regulated power supply  1 
CRO  1 
IC 741  1 
Resistors 10k, 100K  1 each 
Resistors 1.5 k, 150  1 each 
Capacitor 0.01F, 0.1F  1 each 
Function generator 1 Hz to 2MHz  1 
Connecting wires 
Circuit diagrams:
Practical Integrator R_{f} = 100k, R_{1 }= 10K, C_{f }= 0.1f
Fig 1. Integrator Circuit
Practical Differentiator R_{f} = 1.5 k, R_{1 }= 150, C_{f }= 0.1f, C_{1 }= 0.01f
Fig 2. Differentiator circuit
Procedure:
INTEGRATOR:
 Connect the circuit as shown in fig 1.
 Apply a symmetrical square wave of 2Vpp amplitude and 1 KHz frequency.
 Connect the input and output of the circuit to channel 1 and channel 2 of the CRO respectively and observe the waveforms.
 Draw the waveforms along with the levels on a graph.
 Compare the practical values with theoretical values.
 Repeat the same for sinewave.
DIFFERENTIATOR:
 Connect the circuit as shown in fig 2.
 Apply a symmetrical triangular wave of 2Vpp amplitude and 1KHz frequency.
 Connect the input and output of the circuit to channel 1and channel 2 of the CRO respectively and observe the waveforms.
 Draw the waveforms along with the levels on a graph.
 Compare the practical values with theoretical values.
 Repeat the same for the sinewave.
TABULAR FORM:
INTEGRATOR:
S.No  Input Waveform  Time period  Amplitude  Output waveform  Amplitude  Time period 

1  Square wave (1KHz)  1ms  2Vpp  
2  Sine wave (1KHz)  1ms  2Vpp 
DIFFERENTIATOR:
S.No  Input Waveform  Time period  Amplitude  Output waveform  Amplitude  Time period 

1  Triangular wave (1KHz)  1ms  2Vpp  
2  Sine wave (1KHz)  1ms  2Vpp 
Expected Waveforms:
a. Integrating square wave
b. Integrating sine wave waveform
c. Differentiator output for square wave
d. Differentiator output for sine wave waveform
Result: Designed and verified differentiator and integrator circuits using OpAmp 741.
Outcome: After conducting this experiment students are able to design the circuits using opamps to perform integration and differentiation operations for different waveforms.
Viva Questions:
1. Define integrator.
Ans: An integrator is a device to perform the mathematical operation known as integration, a fundamental operation in calculus. The integration function is often part of engineering and scientific calculations. Electronic analog integrators were the basis of analog computers.
2. Define differentiator.
Ans: A Differentiator is a circuit that is designed such that the output of the circuit is proportional to the time derivative of the input.
3. Write down output voltage formula for the integrator.
Ans:
4. Write down output voltage formula for the differentiator.
Ans:
5. What is the output of the differentiator for square wave input?
Ans: Spikes
6. What are the problems in an ordinary opamp differentiator? What are the changes in the circuit of the practical differentiator to eliminate these problems?
Ans: Problems in an Ordinary opamp differentiator are instability and high frequency noise. A Resistor is added in series with the capacitor at the input and a capacitor is added in parallel to the resistor in the feedback circuit in the practical differentiator to eliminate the above problems.
7. What are the problems in an ordinary opamp Integrator? What are the changes in the circuit of a practical integrator?
Ans: The gain of an integrator at low frequency is very high and the circuit goes to saturation. The feedback capacitor is shunted with a resistor in the practical integrator to overcome the above problem.
8. What is a lossy integrator?
Ans: The practical integrator is known as lossy integrator.
9. How a sine wave and cosine wave can be discriminated?
Ans: When t = 0, Sine wave amplitude is zero and the cosine wave amplitude is maximum.
10. Why integrators are preferred over differentiators in electronic circuits?
Ans: In differentiators, the gain increases at high frequency and are not stable.

UpdatedOct 14, 2016

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