EXPERIMENT NO.

1
OBJECT: To measure the parameter of op-amp.

APPARATUS REQUIRED: Bread Board, IC741, Resistors, DC Supply Function Generator,

Multi meter, CRO Probes, Connecting Wires.

THEORY:
An op-amp is a high gain, direct coupled differential linear amplifier choose response
characteristics are externally controlled by negative feedback from the output to input, op-amp
has very high input impedance, typically a few mega ohms and low output impedance, less than
100Ω. Op-amps can perform mathematical operations like summation integration,
differentiation, logarithm, anti-logarithm, etc., and hence the name operational amplifier op-
amps are also used as video and audio amplifiers, oscillators and so on, in communication
electronics, in instrumentation and control, in medical electronics, etc.
Circuit symbol and op-amp terminals:
The circuit schematic of an op-amp is a triangle as shown below in Fig. 1-2-1 op-amp has two
input terminal. The minus input, marked (-) is the inverting input. A signal applied to the minus
terminal will be shifted in phase 180o at the output. The plus input, marked (+) is the non
inverting input. A signal applied to the plus terminal will appear in the same phase at the output
as at the input. +VCC denotes the positive and negative power supplies. Most op-amps operate
with a wide range of supply voltages. A dual power supply of +15V is quite common in practical
op-amp circuits. The use of the positive and negative supply voltages allows the output of the op-
amp to swing in both positive and negative directions.

Fig. op-amp circuit symbol

Op-amp characteristics:
The ideal behavior of an op-amp implies that
a. The output resistance is zero.
b. The input resistance seen between the two input terminals (called the differential input
resistance) is infinity.
c. The input resistances seen between each input terminal and the ground (called the common
mode input resistance) are infinite.
d. op-amp has a zero voltage offset ie., for V1 = V2 = 0, output voltage VO = 0
e. Common mode gain AC is zero.
f. Differential mode gain, Ad is infinity.
g. Common Mode Rejection Ratio (CMRR) is infinity
h. Bandwidth is infinite, ie., Ad is real and constant.
i. Slew rate is infinite.
j. Since VO = Ad (V1 – V2) and Ad = ∞
V1-V2 = VO/Ad = 0
ie.,V1 = V2
The above condition implies that the inverting and non-inverting terminals are at the same
potential because of the very high (infinite) gain property. This condition along with the
condition i1 = i2 = 0 are the keys to the simplified analysis of the op-amp circuits.
An ideal op-amp draws no current from the source and its response is also independent of
temperature. However, a real op-amp does not work this way. Current is taken from the source
into op-amp inputs. Also the two inputs respond differently to current and voltage due to
mismatch in transistors. A real op-amp also shifts its operation with temperature. These non-
ideal characteristics are:

(a)Input Impedance:
• Impedance is calculated on one input when the other is ground.
• Equal to transistor base/gate impedance with feedback.
• Bipolar input (741) -2 MΩ.
• JFET input (TL071) -10 12 Ω.
(b)Output Impedance:
• Intrinsic output impedance is measured with no feedback.

• Operational voltage feedback reduces the output impedance.

• The output impedance is: Z’out = vth / is.

• The thevenin output voltage is: vth = -iin Rf.
• With vout shorted to ground, vA = iin Rf.
• Internally the voltage drop is is Zout = A0 vA = A0 iin Rf.

(c)Input offset voltage:

Ideally, the output voltage should be zero when the voltage between the inverting and non
inverting inputs is zero. In reality, the output voltage may not be zero with zero input voltage.
This is due to un-avoidable imbalances, mismatches, tolerances, and so on inside the op-amp. In
order to make the output voltage zero, we have to apply a small voltage at the input terminals to
make output voltage zero. This voltage is called input offset voltage .i.e., input offset voltage is
the voltage required to be applied at the input for making output voltage to zero volts. The 741
op-amp has input offset voltage of 5mV under no signal conditions. Therefore, we may have to
apply a differential input of 5mV, to produce an output voltage of exactly zero.

(d)Input bias current:

The op-amp’s input is a differential amplifier, which may be made of. BJT or FET. In either
case the input transistors must be biased into this linear region by supplying currents into the
bases.
In an ideal op-amp, no current is drawn from the input terminals. However, practically, input
terminals conduct a small value of dc current to bias the input transistors when base currents
flow through external resistances, they produce a small differential input voltage or unbalance;
this represents a false input signal. When amplified, this small input unbalance produces an
offset in the output voltage.
The input bias current shown on data sheets is the average value of base currents entering into
the terminals of an op-amp.
(e)Slew rate:
Among all specifications affecting the ac operation of the op-amp, slew rate is the most
important because it places a severe limit on a large signals operation. Slew rate is defined as the
maximum rate at which the output voltage can change. The 741 op-amp has a typical slew rate of
0.5 volts per microsecond (V/μs). This is the ultimate speed of a typical 741; its output voltage
can change no faster than 0.5V/μs. If we drive a 741 with large step input, it takes 20μs (0.5
V/μsX10V) for the output voltage to change from 0 to 10V.
• Slew rate measures the speed that the op-amp can respond to a changing input voltage.
• Slew rate is particularly important in digital applications –square waves with rapid voltage
changes.

(f) Common mode rejection ratio (CMRR):

In an ideal different amplifier, Ad is infinite while AC must be zero. However, in a practical
differential amplifier; Ad is very large and AC is very small. ie., the differential amplifier
provides very large amplification for difference signals and very small amplification for common
mode signals.
Many disturbance signals/noise signals appear as a common input signal to both the input
terminals of the differential amplifier. Such a common signal should be rejected by the
differential amplifier. “The ability of a differential amplifier to reject a common-mode signal is
expressed by a ration called Common Mode Rejection Ratio, denoted as CMRR”.
CMRR is defined as the ratio of the differential voltage gain Ad to common mode voltage
Gain Ac.
• Typical CMRR = A0 / ACM = 60 to 120 dB.
• Corresponding gain makes ACM on the order of 1.
• Input bias current adds to common-mode gain, but can be corrected.

• The bias current is pulled into the inverting input through both R1 and R2. If R3 is equal to the

parallel equivalent of R1 and R2 the voltage drops will cancel.

(g)Gain-bandwidth product:
The gain, G is defined as the gain of the op-amp when a signal is fed differentially into the amp
and no feedback loop is present. This gain is ideally infinite, but in reality is finite, and also
depends on the frequency. At low frequency this gain is maximum, decreases linearly with
increasing frequency, and has a value of one at the frequency commonly referred to as the cut-off
frequency (in equation form, Gfc = 1). For the 741 op-amp, fc is given as 1 MHz, and the open-
loop gain at this frequency is simply one. Gf is defined as the gain-bandwidth product, and for all
frequencies this product must be a constant equal to fc . The figure below graphically illustrates
this relationship for the 741 op-amp. When feedback is provided, as in an inverting amplifier, the
gain is given by G = – Rf / R1; however, it must be recognized that the magnitude of this gain
can never exceed the gain as given by the gain-bandwidth product.

(h) POWER SUPPLY REJECTION RATIO (PSRR)

If the supply of an op amp changes, its output should not, but it typically does. If a change of X
volts in the supply produces an output voltage change of Y volts, then the PSRR on that supply
(referred to the output, RTO) is X/Y. The dimensionless ratio is generally called the power
supply rejection ratio (PSRR), and Power Supply Rejection (PSR) if it is expressed in dB.
However, PSRR and PSR are almost always used interchangeably, and there is little
standardization within the semiconductor industry..
PSRR or PSR can be referred either to the output (RTO) or the input (RTI). The RTI value can
be obtained by dividing the RTO value by the amplifier gain. In the case of the traditional op
amp, this would be the noise gain. The data sheet should be read carefully, because PSR can be
expressed either as an RTO or RTI value.
PSR can be expressed as a positive or negative value in dB, depending on whether the PSRR is
defined as the power supply change divided by the output voltage change, or vice-versa. There is
no accepted standard for this in the industry, and both conventions are in use. If the amplifier has
dual supplies, it is customary to express PSR separately for each. This is very useful for
amplifiers that can be used in either dual or single-supply applications.
POWER SUPPLIES AND POWER DISSIPATION:
Op amps have no ground terminal. Specifications for the power supply are quite often in the
form ±X volts, but in fact it might equally be expressed as 2X volts. What is important is where
the CM and output ranges lie relative to the supplies. This information may be provided in
tabular form or as a graph.
Often data sheets will advise that an op amp will work over a range of supplies (from +3 V to
±16.5 V for example), and will then give parameters at several values of supply, so that users
may extrapolate. If the minimum supply voltage is quite high, it is usually because the device
uses a structure requiring a threshold voltage to function (e.g., zener diode).

PROCEDURE:

1. Connect the ckt. According to the dig.

2. Connect +15V to pin no.7 and –15V to pin no.4 of 741.
3. Switch on the power supply.
4. Check the output amplitude on CRO.
5. Observe and get data for characteristics for op-amp 741.

RESULT:

We have measured the op-amp parameter and performed the experiment successfully.
PRECAUTIONS:
(1) Use the component of proper value.
(2) Make the connection tight.
(3) Take care about the voltage limit of +VCC & - VEE.
(4) Check the connections before switch on the power supply.
EXPERIMENT NO.2

(a)OBJECT: Study and design Integrator using op-amp.

APPARATUS REQUIRED: CRO, Function Generator, Bread Board, and 741 IC, ±12V
supply, Resistors, Capacitors and Connecting leads.

THEORY:

Integrator: A circuit in which the output voltage is the integration of the input voltage is called
an integrator.

In the practical integrator to reduce the error voltage at the output, a resistor RF is connected
across the feedback capacitor CF. Thus, RF limits the low-frequency gain and hence minimizes
the variations in the output voltage.
CIRCUIT DIAGRAM:

PROCEDURE:
1) Connect the circuit according to the circuit diagram.
2) Apply square wave to the input terminal of integrator circuit.
3) Set the input voltage 1V peak to peak and frequency at 1KHz.
4) Note down the input and output waveform.
5) Draw the waveform on graph paper.
OBSERVATIONS TABLE:

RESULT:

We have successfully studied and performed the Integrator using op-amp.

PRECAUTIONS:

1. Take care of proper pin configuration of 741.

2. Make the connections tight.
3. Use the components of proper value.
4. Take care about the voltage limit of +Vcc & Vee.
5. Keep the amplitude and frequency of input signal in such a way that output can be observed
clearly.
(b)OBJECT: Study and design Differentiator using op-amp.

APPARATUS REQUIRED: CRO, Function Generator, Bread Board, and 741 IC, ±12V
supply, Resistors, Capacitors and Connecting leads.
THEORY:

Differentiator circuits as its name implies, performs the mathematical operation of differentiator,
that is, the output waveform is the derivative of the input. The differentiator may be constructed
from a basic inverting amplifier when an input resistor R1 is replaced by a capacitor C,

Vo= -RF C d Vin /dt

Thus, the output Vo is equal to the RF C times the negative instantaneous rate of change of
the input voltage Vin with time.
The right-hand side of the capacitor is held to a voltage of 0 volts, due to the "virtual ground"
effect. Therefore, current "through" the capacitor is solely due to change in the input voltage.
A steady input voltage won't cause a current through C, but a changing input voltage will.
Capacitor current moves through the feedback resistor, producing a drop across it, which is
the same as the output voltage. A linear, positive rate of input voltage change will result in a
steady negative voltage at the output of the op-amp. Conversely, a linear, negative rate of
input voltage change will result in a steady positive voltage at the output of the op-amp. This
polarity inversion from input to output is due to the fact that the input signal is being sent
(essentially) to the inverting input of the op-amp, so it acts like the inverting amplifier
mentioned previously. The faster the rate of voltage change at the input (either positive or
negative), the greater the voltage at the output.
The formula for determining voltage output for the differentiator is as follows:

CIRCUIT DIAGRAM:
PROCEDURE:

1. Connect the circuit as per the circuit diagram.

2. Apply the input signals i.e, Sinusoidal, Square waves.
3. Check the output waveform i.e, the wave shape of the signal.
4. Note that the output will be the differentiation of the applied signal or not.
5. Plot various input output wave shapes.

OBSERVATIONS TABLE:

GRAPH:

RESULT:

We have successfully studied and performed the Differentiator using op-amp.

PRECAUTIONS:
1. Take care of proper pin configuration of 741.
2. Make the connections tight.
3. Use the components of proper value.
4. Take care about the voltage limit of +Vcc & Vee.
5. Keep the amplitude and frequency of input signal in such a way that output can be observed
clearly.
EXPERIMENT NO.3

RC PHASE SHIFT AND WIEN BRIDGE OSCILLATORS USING IC741

OP-AMP

(a) RC Phase Shift Oscillator:

OBJECT: Study and design RC Phase Shift Using IC741 Op-amp.

APPARATUS REQUIRED: Bread Board CRO Probes Connecting wires 741 Op-amp, Resistors,
Capacitors.

THEORY:

Oscillator is a circuit which generates output without any input. Oscillator can be defined as a
device that converts dc to ac. Oscillators can be classified as: Based on the components used: RC
Oscillators - RC Phase shift, Wien Bridge Oscillator LC Oscillators - Colpitts, Hartley, Clapp
Oscillator Crystal Oscillators Based on the type of waveform: Sinusoidal Oscillators – RC Phase
shift, Wien Bridge, Colpitts, Hartley, Non-Sinusoidal Oscillators- UJT relaxation Oscillators
Based on frequency range: Audio frequency oscillator – RC oscillators Radio frequency
oscillator – LC oscillators Barkhausen criterion for oscillations:
1) For sustained oscillations the phase shift around the circuit( amplifier and feedback circuit)
should be 360o or 0o.
2) The magnitude of the loop gain of the oscillator should be greater than or equal to 1.
A Phase shift oscillator consists of an Op-Amp as the amplifying stage and three RC cascaded
networks as the feedback circuit. The feedback circuit provides feedback voltage from the output
back to the input of the amplifier. The Op-Amp is used in the inverting mode, therefore any
signal that appears at the inverting terminal is shifted by 180o at the output. An additional 180o
phase shift required for oscillation is provided by the 3 RC sections – each section providing a
Phase shift of 60o. Thus the total phase shift around the loop is 360 o (or 0o). At some specific
frequency when the phase shift of the cascaded IC Applications Lab Manual ECE, MRCET 27
RC sections is exactly 180o and the gain of the amplifier is sufficiently large, the circuit will
oscillate. This frequency is called the frequency of oscillation fo and is given by fo = 1/2πRC√6
= 0.065/ RC At this frequency, the magnitude of gain Av must be at least 29 i.e., Rf/R1 = 29.
Thus the circuit will produce a sinusoidal waveform of frequency fo if the gain is 29 and the total
Phase shift around the circuit is exactly 360o or 0o.

CIRCUIT DIAGRAM:

PROCEDURE:
1. Connect the components/equipment as shown in the circuit diagram.
2. Switch ON the power supply.
3. Connect the output of the circuit to CRO through probes.
4. Adjust the potentiometer to get the accurate sinusoidal waveform on CRO.
5. Calculate the practical frequency of oscillation fo = 1/T by observing the time period of the
output sinusoidal waveform on the CRO and compare it with theoretical frequency of oscillation
fo = 1/2πRC√6
6. Sketch the output waveform by noting the time period and peak to peak voltage of the output
waveform.
OBSERVATIONS TABLE:

EXPECTED WAVEFORM:

RESULT:

We have successfully studied and performed the RC phase shift oscillator using op-amp.

PRECAUTIONS:
 Use the component of proper value.
 Make the connection tight.
 Take care about the voltage limit of +VCC & - VEE.
 Take care of proper pin configuration of 741.
b) Wien Bridge Oscillator:

OBJECT: Study and design Wien Bridge Oscillator Using IC741 Op-amp.

APPARATUS REQUIRED: Bread Board CRO Probes Connecting wires 741 Op-amp, Resistors,
Capacitors.

THEORY:

Because of its simplicity and stability, one of the most commonly used audio-frequency oscillators is
the Wien Bridge. The circuit diagram shows the Wien Bridge oscillator in which the Wien Bridge
circuit is connected between the amplifier input terminals and output terminal. The bridge has a
series RC network in one arm and a parallel RC network in the adjoining arm. In the remaining two
arms of the bridge, resistors R1 & Rf are connected. The feedback signal in this circuit is connected to
the non-inverting terminal, therefore the Op-Amp is working in non-inverting mode. Hence this
amplifier doesn‟t provide any phase shift. Therefore the feedback network need not provide any
phase shift. The condition of zero Phase shift around the circuit is achieved by balancing the bridge.
When the bridge is balanced, the frequency of oscillation f o is exactly the resonant frequency which
is given by the equation fo = 1/2πRC = 0.159/RC At this frequency the gain A v required for sustained
oscillation is 3(practically it is more). i.e. A v = 1+Rf/R1 = 3.

CIRCUIT DIAGRAM :
PROCEDURE:
1. Connect the components/equipment as shown in the circuit diagram.
2. Switch ON the power supply.
3. Connect the output of the circuit to CRO through probes.
4. Adjust the potentiometer to get the accurate sinusoidal waveform on CRO.
5. Calculate the practical frequency of oscillation fo = 1/T by observing the time period of the
output sinusoidal waveform on the CRO and compare it with theoretical frequency of oscillation
fo = 1/2πRC
6. Sketch the output waveform by noting the time period and peak to peak voltage of the output
waveform.

OBSERVATIONS TABLE:

EXPECTED WAVEFORMS:
RESULT:

We have successfully studied and performed the Wein’s bridge oscillator using op-amp.

PRECAUTIONS:
 Use the component of proper value.
 Make the connection tight.
 Take care about the voltage limit of +VCC & - VEE.
 Take care of proper pin configuration of 741.
 EXPERIMENT NO.-4

OBJECT: To study and design first order LPF, HPF and Band notch/reject filters using op-amp
IC741 and to obtain frequency response.
APPARATUS REQUIRED:

THEORY:
LOW PASS FILTER:
A frequency selective electric circuit that passes electric signals of specified band of frequencies
and attenuates the signals of frequencies outside the brand is called an electric filter. The first
order low pass filter consists of a single RC network connected to the non-inverting input
terminal of the operational amplifier. Resisters R1 and RF determine the gain of the filter in the
pass band. The low pass filter as maximum gain at f = 0Hz. The frequency range from 0 to FH is
called the pass band the frequency range f > fh is called the stop band.
The first order low pass butter worth filter uses an Rc network for filtering. The op-amp is used
in the non inverting configuration, hence it does not load down the RC network. Resistor R1 and
R2 determine the gain of the filter.
V0/Vin = Af /(1+ jf/f h)
Af = 1+ Rf /R1= passband gain of filter
F=frequency of the input signal
Fh=1/2ΠRC =High cut off frequency of filter
V0/Vin=Gain of the filter as a function of frequency
The gain magnitude and phase angle equations of the LPF the can be obtained by converting
V0/Vin into its equivalent polar form as follows|V0/Vin| = Af /(√1 +(f/f l2) Φ =- t a n - 1 ( f / f h)
Where Φ is the phase angle in degrees. The operation of the LPF can be verified From the gain
magnitude equation.
HIGH PASS FILTER:
High pass filters are often formed simply by interchanging frequency. Determining resistors and
capacitors in LPFs that is ,a first order HPF is formed from a first order LPF by interchanging
components ‘R’ and ‘C’ figure. Shows a first order butter worth HPF with a lower cut off
frequency of ‘ Fl’. This is the frequency at which magnitude of the gain is 0.707 times its pass
band value. Obviously all frequencies, with the highest frequency determinate by the closed loop
band width of op-amp. For the first order HPF the output voltage is
V0= [1+Rf /R1]j2ΠRCVin/(1-j2ΠfRC)
V0/Vin=Af [j(f/f l)/(1=j(f/f l)]
Where Af +Rf /R1pass band gain of the filter.
F =frequency of input signal.
Fl=1/2ΠRC = lower cut off frequency
Since, HPFs are formed from LPFs simply by interchanging R’s and C’s .The design and
frequency scaling procedures of the LPF share also applicable to HPFs.
Band Reject or Notch filter: - Notch filter is generally known as narrow band reject filter. In
this filter frequency are attenuated in the stop band while they are passed outside this band. The
bandwidth of this filter is much smaller due to its higher Q (> 10). the notch output frequency at
which maximum attenuation occurred, is given by:
F N = 1 / (2 П R C)

CIRCUIT DIAGRAM:
LPF:

HPF:

BNF:
PROCEDURE:

1. Connections are made as per the circuit diagram.

2. Apply sine wave of amplitude 2Vp-p to the non inverting input terminal.
3. Values the input signal frequency.
4. Note down the corresponding output voltage.
5. Calculate gain in db.
6. Tabulate the values.
7. Plot a graph between frequency and gain.
8. Identify stop band and pass band from the graph.

OBSERVATION TABLE :(LPF )

OBSERVATION TABLE:(HPF)
OBSERVATION TABLE :(BNF )

CALCULATIONS LPF:
Fh=1/2πRC
Fh=1/2πx15kx0.01μf
= 1k
Choose c=0.01μf
Av=1+Rf/R1
With this
R1=10k
Rf=10k

HPF:
Choose a standard value of Capacitor C say 0.01 μF
Then fL=1/2πRc
1/2πx15kx0.01μf
= 1k
FL=1k
A=1+Rf/R1
With this
R1=10k
Rf=10k

MODEL GRAPH:
LPF:

HPF:

RESULT:-
HPF : The obtained gain Av =__________
The band width =__________
LPF: The obtained gain Av =__________
The band width =__________
BNF: The obtained gain Av =__________
The band width =__________
The HPF, LPF and BNF filters are designed and obtained gain is found to be equal to the
theoretical value of gain. The frequency response of LPF, HPF and BNF is plotted using IC741
Op-Amp.

PRECAUTIONS:
 Use the component of proper value.
 Make the connection tight.
 Take care about the voltage limit of +VCC & - VEE.
 Take care of proper pin configuration of 74.

EXPERIMENT No.5

OBJECT: Study and design square wave generator and saw-tooth wave generator using op amp
741.

APPARATUS REQUIRED: CRO, Function Generator, Power supply, Bread Board, 741 IC,

Resistors, capacitor and connecting leads.

THEORY:

Square wave generator :

Square waves are generated when the op-amp is forced to operate in the saturation region. That
is, the output of the op amp is forced to swing respectively between +Vsat and – Vsat. Resulting
in the generation of square wave. The square wave generator is also called a free –running or
astable multivibrator. Assuming the voltage across capacitor C is zero at the D.C. supply voltage
+Vcc and –VEE are applied. Initially the capacitance C acts, as a short circuit. The gain of the
op-amp is very large hence V1 drives the output of the op-amp to its saturation.

Saw-tooth wave generator :

sawtooth waveform can be also generated by an asymmetrical astable multivibrator followed by
an integrator  The sawtooth wave generators have wide application in time-base generators and
pulse width modulation circuits.
The difference between the triangular wave and sawtooth waveform is that the rise time of
triangular wave is always equal to its fall of time while in saw tooth generator, rise time may be
much higher than its fall of tim , vise versa . The triangular wave generator can be converted in
to a sawtooth wave generator by injencting a variable dc voltage into the non inverting terminal
of the  integrator.

CIRCUIT DIAGRAM:
 SQUARE WAVE GENERATOR

SAW-TOOTH WAVE GENERATOR

PROCEDURE:
1. Connect the circuit as shown in figure.
2. Switch on the power supply.
3. No. Input signal is feed from function generator. It is self generating.
4. Frequency can be varied by changing RC combination.
5. Output is obtained at pin 6 of op-amp

WAVEFORMS:
RESULT: We have successfully studied and obtained Square Wave on CRO.

PRECAUTIONS:
1. Take care of proper pin configuration of 741.
2. Make the connections tight.
3. Use the components of proper value.
4. Take care about the voltage limit of +Vcc & Vee.
5. Keep the amplitude and frequency of input signal in such a way that output can be observed
clearly.
 EXPERIMENT No.6
OBJECT: To study and design Instrumentation Amplifier Using Op-amp.

APPARATUS REQUIRED: Op-Amp (μA -741), DC Power Supply (12-0- 12) V, CRO (0-
20MHz range), Resistors 1KΩ, 10KΩ 5) Bread board.
THEORY:

Instrumentation amplifier: The instrumentation amplifier is a differential amplifier that has high
input impedance and the capability of gain adjustment through the variation of a single resistor.

Instrumentation amplifier circuit

The voltage drop across R gain is equal to the voltage difference of two input signals. Therefore,
the current through R gain caused by the voltage drop must flow through the two “R” resistors
above and below R gain. It has been shown in class that the output is given by

Though this configuration looks cumbersome to build a differential amplifier, the circuit has
several properties that make it very attractive. It presents high input impedance at both terminals
because the inputs connect into non inverting terminals. Also a single resistor Regain can be used
to adjust the voltage gain.

PROCEDURE:
1. Connect the circuit and use the component values determined in the pre lab. Use the dual
power supply of ±7 V.
2. Apply a 1 KHz, 1Vpp sine wave to input 1 and a 1V dc voltage from the power supply for
input2. Make accurate sketches of the input and output waveforms on the same axis in time
domain. The oscilloscope’s input should be “DC” coupled.
3. Get a hardcopy output from the scope display with input and output waveforms to confirm that
the circuit operates as an instrumentation amplifier where the output voltage is a linear
combination of the input waveforms.

RESULT:

We have successfully studied and performed the Instrumentation amplifier using op-amp.

PRECAUTIONS:

1. Take care of proper pin configuration of 741.

2. Make the connections tight.
3. Use the components of proper value.
4. Take care about the voltage limit of +Vcc & Vee.
5. Keep the amplitude and frequency of input signal in such a way that output can be observed
clearly.
 EXPERIMENT No.7
OBJECT: To study and design Comparator circuits using OP-AMP IC741.

APPARATUS REQUIRED: Bread Board, IC741, Resistors DC Supply Function Generator,

Multi meter, CRO Probes, Connecting Wires.

THEORY:

Comparator: A Comparator is a non-linear signal processor. It is an open loop mode application of

Op-amp operated in saturation mode. Comparator compares a signal voltage at one input with a
reference voltage at the other input. Here the Op-amp is operated in open loop mode and hence the
output is ±Vsat. It is basically classified as inverting and non-inverting comparator. In a non-inverting
comparator Vin is given to +ve terminal and V ref to –ve terminal. When Vin < Vref, the output is –Vsat
and when Vin > Vref, the output is +V sat (see expected waveforms). In an inverting comparator input is
given to the inverting terminal and reference voltage is given to the non inverting terminal. The
output of the inverting comparator is the inverse of the output of non-inverting comparator. The
comparator can be used as a zero crossing detector, window detector, time marker generator and
phase meter.

CIRCUIT DIAGRAM:

PROCEDURE:
1. Connect the components/equipment as shown in the circuit diagram.
2. Switch ON the power supply.
3. Apply 1 KHz sine wave with 5 V pp at the non-inverting input terminal of IC741 using a function
generator.
4. Apply 1V dc voltage as reference voltage at the inverting terminal of IC741.
5. Connect the channel-1 of CRO at the input terminals and channel-2 of CRO at the output
terminals.
6. Observe the input sinusoidal signal at channel-1 and the corresponding output square wave at
channel-2 of CRO. Note down their amplitude and time period.
7. Overlap both the input and output waves and note down voltages at positions on sine wave where
the output changes its state. These voltages denote the Reference voltage.
8. Plot the output square wave corresponding to the sine input with V ref = 1V.

OBSERVATIONS TABLE:

EXPECTED WAVEFORMS: Comparator input & output waveform.

RESULT:
We have successfully studied and performed a comparator using op-amp.

PRECAUTIONS:

1. Take care of proper pin configuration of 741.

2. Make the connections tight.
3. Use the components of proper value.
4. Take care about the voltage limit of +Vcc & Vee.
5. Keep the amplitude and frequency of input signal in such a way that output can be observed
clearly.
 EXPERIMENT NO.8
OBJECT: To study and design voltage to current And Current to voltage converter using op-
amp.

APPARATUS REQUIRED: 741CP op-amp, resistor, potentiometer, Digital multimeter,

(DMM) Oscilloscope, DC power supply.

THEORY:

Op-amps also make excellent voltage-to-current and current-to-voltage converters. These

converters are in effect transducers which take a signal in one form, either voltage or current, and
convert it to a signal of the other form. When analog voltage signals must be transmitted long
distances by wire circuits, it is common to convert the voltage signal to a current for transmission
and then back to a voltage at receiving end. This technique eliminates problems due to voltage
drops in along circuit. The current path, called a current loop, is a series circuit. Since the current
at all points in a series circuit must be the same, signal level is independent of circuit length.

Current to Voltage Converter :

Current to voltage converter

Point A is held at zero volts (a virtual ground) by the output of the op-amp; and since most of Iin
must flow through Rf, Vo must be approximately;
Voltage to Current Converters:

Voltage to current converter

The current through the load

Schematic diagram of the current to voltage converter circuit:

PROCEDURE:
1. Build the circuit. Be sure E is initially set to zero.
2. Apply power to the circuit and by adjusting the potentiometer.
3. Measure the values of E and Vo corresponding to different in values. Record these values in
the table.
OBSERVATIONS TABLE:
Schematic Diagram of the voltage to current converter circuit:

PROCEDURE:
1. Build the circuit.
2. By adjusting the potentiometer, measure and record the values of load current (current through
milliammeter ) for input voltages from 0 to +5 volts.

OBSERVATIONS TABLE:

RESULT:

We have successfully studied and performed the voltage to current and current to voltage
converter using op-amp.

PRECAUTIONS:
1. Take care of proper pin configuration of 741.
2. Make the connections tight.
3. Use the components of proper value.
4. Take care about the voltage limit of +Vcc & Vee.
5. Keep the amplitude and frequency of input signal in such a way that output can be observed
clearly.
EXPERIMENT NO.10
OBJECT: Study and design of IC 555 as astable, monostable and bistable multivibrator.

APPARATUS REQUIRED: IC 555, CRO, Function Generator, Bread Board, Resistors,

capacitor and connecting leads.
THEORY:

555 Timer - An 8 pin IC designed for use in a variety of switching applications.

Multivibrator - A circuit designed to have zero, one, or two stable output states.
There are three types of multivibrators:
1) Astable (or Free-Running Multivibrators)
2) Monostable (or One-Shot)
3) Bistable (or Flip- Flop)

1). Astable multivibrator – A switching circuit that has no stable output state. The astable
multivibrator is a rectangular wave oscillator. Also referred to as a free-running multivibrator.
The IC555 timer is a 8 pin IC that can be connected to external components for astable operation.
The simplified block diagram is drawn. The OP-AMP has threshold and control inputs.
Whenever the threshold voltage exceeds the control voltage, the high output from the OP –AMP
will set the flip-flop. The collector of discharge transistor goes to pin 7. When this pin is
connected to an external trimming capacitor, a high Q output from the flip flop will saturate the
transistor and discharge the capacitor.
When Q is low the transistor opens and the capacitor charges. The complementary signal out
of the flip-flop goes to pin 3 and output. When external reset pin is grounded it inhibits the
device. The on – off feature is useful in many application. The lower OP- AMP inverting
terminal input is called the trigger because of the voltage divider. The non-inverting input has
a voltage of +Vcc/3, the OP-Amp output goes high and resets the flip flop.
The output frequency is,
f = 1.44/(RA + RB)C
The duty cycle is,
D = RB / (RA + 2RB) * 100%
The duty cycle is between 50 to 100% depending on RA and RB.
2). Monostable multivibrator – A switching circuit with one stable output state. Also
referred to as a one-shot. The one-shot produces a signal output pulse when it receives a
valid input trigger signal.
This circuit is a monostable multivibrator, or one-shot, made with a 555 timer chip. Click the
logic input on the left (the "H"), and the output goes high for a short time, and then it goes
low again.
A timing interval starts when the trigger input ("tr") is brought low. When this happens, the 555
output goes high. This causes the capacitor to be charged until it reaches 6.67V. Then, the timing
interval ends, the output goes low, and the capacitor is discharged through the input. The
capacitor in front of the trigger input causes the monostable to be negative-edge triggered. If the
capacitor is replaced with a wire, and the logic input is held low too long, then the 555's output
will start to oscillate.
3). Bistable multivibrator – A switching circuit with two stable output states. Also referred
to as a flip-flop. The output changes state when it receives a valid input trigger signal, and
remains in that state until another valid trigger signal is received.

DIAGRAM:
Practical Circuit Diagram:
PROCEDURE:
Astable multivibrator:
1) Connect the circuit using the component values as per the design.
2) Observe and sketch the capacitor voltage wave form (pin-6) and output waveform
(pin-3) measure the frequency and duty cycle of the output wave form.
3) Connect the circuit of fig using component values as per the design and repeat the
step 2 by adjusting both the potential meters for duty cycle of 10%, 50% and 90%
with a frequency of 1 kHz.

Monostable Multivibrator:
1) Connect the circuit using the component values as per the design.
2) Set the square wave 2.5V peak and 1KHz trigger input on function generator.
3) Apply the trigger input at pin-2 through capacitor C1. Observe both trigger input and
the output of the multivibrator on CRO simultaneously and sketch the waveforms.
4) Repeat the step 3 for trigger input of 2KHz frequency.

WAVEFORMS:
 RESULT:
We have successfully study and design the IC 555 as astable, monostable and bistable
multivibrator.
PRECAUTIONS:
 Use the component of proper value.
 Make the connection tight.
 Take care about the voltage limit of VCC.
 Take care of proper pin configuration of 555 IC.
.