Experiments 6 - 10

EC2700 LAB
Roll No: 120CH0057
Name: Siddharth Gautam
Date of Submission: 19-11-2021
EXPERIMENT - VI
Aim: Input and Output characteristics of BJT.

Components Required: Resistor (1K-ohm and 470K-ohm resistor), Transistor (1 BC547

transistor), Single strand wires as needed, Bread Board.

Measuring Equipment Required: PSU, Ammeter, Voltmeter.

Principle: The three terminals of a BJT are Emitter (E), Collector(C) and Base (B). The
Common Emitter (CE) configuration is the most frequently encountered configuration. In
this the emitter is common or reference to both the input and output terminals (in this
case common to both the base and collector terminals). Two sets of characteristics are
necessary to fully describe the behaviour of the CE configuration: input and output
characteristics.

Procedure:

● For Input Characteristics

1. Connect the circuit in the following manner.

2. Set 𝑉𝐶𝐸 (BAT1) at 1V.

 3. Increase the input voltage for 𝑉𝐵𝐸 (BAT2) in steps of 0.5V and note the
corresponding 𝐼𝐵.
4. Repeat for 𝑉𝐶𝐸 = 2𝑉

𝑉1 𝐼𝐵 (𝑉𝐶𝐸 = 1) 𝑉𝐵𝐸 (𝑉𝐶𝐸 = 1) 𝐼𝐵 (𝑉𝐶𝐸 = 2) 𝑉𝐵𝐸(𝑉𝐶𝐸 = 2)

0 0 0 0 0

0.5 0 0.49 0 0.49

1.0 0.261 0.74 0.299 0.74

1.5 0.785 0.78 0.733 0.755

2.0 1.202 0.79 1.3 0.756

2.5 1.703 0.80 1.729 0.764

3.0 2.196 0.81 2.238 0.768

3.5 2.677 0.82 2.786 0.771

4.0 3.195 0.827 3.22 0.777

4.5 3.728 0.836 3.781 0.781

5.0 4.194 0.84 4.246 0.789

● Output Characteristics

1. Set up the circuit as shown in the diagram.

2. For 𝑅1 = 1𝑀Ω, set 𝐼𝐵 = 4. 3 µ𝐴.
3. Vary 𝑉2 in steps of 1V and note the corresponding 𝐼𝐶 and 𝑉𝐶𝐸.
4. Repeat for 𝑅3 = 470𝑘Ω and 𝐼𝐵 = 10µ𝐴.
EXPERIMENT VII
Aim: To design an RC-coupled amplifier

Components Required: 1 BC548 transistor, 1 68K-Ohm resistor, 1 18K Ohm resistor. 1

1.2 K-Ohm resistor, 1 K-Ohm resistor, 2 1 nF capacitor, 1 33nF capacitor.

Equipment Required: Function generator, DSO, Voltmeter, Ammeter, Bread Board.

Theory: An amplifier is a device that is used to amplify input voltage or current. The RC
coupled CE transistor amplifier is a popular scheme of cascading two or more amplifiers
to achieve the required levels of amplification. The interstage coupling is done by using a
RC network, hence the name.The variation of gain with frequency of an amplifier is
called the frequency response characteristics of the amplifier. The bandwidth of the RC
amplifier is the difference between upper cut-off frequency and lower cut-off frequency.
It represents the range of frequencies that the amplifier is most effective in amplifying.
The cut-off frequency points are determined from the frequency response graph, where
the gain (dB) is 3 dB lower than the maximum gain. For a transistor to act as an amplifier,
it must be properly biased. i.e. its emitter base junction must be forward biased and
collector base junction must be reverse biased. The transistor is operating in the active
region, and is verified by measuring the DC bias conditions.

Circuit Diagram(s):
Procedure:

Connect the components as shown in the diagram.

1. Apply a 50mv peak-to-peak signal from the function generator to the input of the
amplifier and measure output voltage in the CRO. Note down the Vpk-pk readings for
different frequencies keeping the input signal constant.

2. Calculate the voltage gain in dB for each frequency and plot the frequency response
curve in a semi-log graph paper. From it find the bandwidth.

3. In the mid frequency, select any frequency, go on increasing the input, observing the
output in the oscilloscope. At some value of input, the output waveform starts showing
distortion. That input value in volts or mv is called the signal handling capacity.
EXPERIMENT VIII
Aim: Design of inverting and non-inverting amplifiers using Op-Amp.

Components Required: 1 IC741 amplifier, 1 1K-Ohm resistor, 1 3.9K-Ohm resistor.

Equipment Required: Multimeter, CRO, Bread Board, Function Generator, Power

Supply

Theory: An Operational Amplifier or OpAmp is a very high gain differential amplifier

with high input impedance and low output impedance. The basic circuit is made using a
difference amplifier having two inputs and one output. The plus (+) input produces an
output that is in phase with the signal applied, whereas an input to the minus (-) input
results in an opposite polarity output. Most existing OPAMPs are produced on a single
semiconductor substrate as an Integrated Circuit (IC741).

Procedure:

1. The OpAmp was set up as per the circuit diagram (inverting or non-inverting as
the case may be).

2. Power supply was provided and the gain of the amplifier was measured by noting
down the output voltage with a multimeter.

3. The gain was determined with the value of feedback resistor(Rf) keeping the input
resistance constant(Rin).
Circuit Diagrams:
 Inverting Amplifier

Non-Inverting Amplifier

Observation Table

Type Input Output Theoretical Practical Phase

Gain Gain Difference
(DEG)

Inverting 1V -4V -3.9V -3.96 180

Non-Inverti 1V 5.52V 4.9V 4.84 0

ng
EXPERIMENT IX
Aim: To design a low pass and high pass filter.

Components required: 1 10K-ohm resistor, 1 0.01mF capacitor.

Equipment required: Function generator, Bread board, CRO

Theory: A filter is a circuit that passes a specific range of frequencies while rejecting
other frequencies. A passive filter consists of passive circuit elements,such as capacitors,
inductors, and resistors. The most common way to describe the frequency response of a
filter is to plot the filter voltage gain (Vout/Vin) in dB as a function of frequency (f). The
frequency at which the output power gain drops to 50% of the maximum value is called
the cut-off frequency (fc). When the filter dB voltage gain is plotted as a function of
frequency on a semi log graph using straight lines to approximate the actual frequency
response, it is called a Bode plot. A Bode plot is an ideal plot of filter frequency response
because it assumes that the voltage gain remains constant until the cut-off frequency is
reached.

● Low pass filter: A low-pass filter (LPF) is designed to pass all frequencies below
the cut-off frequency and reject all frequencies above the cut-off frequency. It is
simply an RC series circuit across the input, with the output taken across the
capacitor. At the cut-off frequency, the capacitive reactance of capacitor C is equal
to the resistance of resistor R, causing the output voltage to be 0.707 times the
input voltage (-3dB).

● High pass filter: A high-pass filter (HPF) is designed to pass all frequencies
above the cutoff frequency and reject all frequencies below the cut-off frequency.It
is simply an RC series circuit across the input, with the output taken across the
resistor.
Circuit diagram:

Procedure:

1. Connect the components as shown in the diagram.

2. Set up the circuit as shown taking the output across the capacitor (For HPF set the
circuit as shown and take the output across the resistor). The input for the filter is
taken from the output of the function generator. The input to filter is also
connected to channel 1 and the output is connected to channel 2 of the CRO

3. Vary the frequency of the input signal over a wide frequency range (but keep the
input amplitude fixed). Note the Values of Vout for each frequency and calculate
the corresponding Gain.
Observations

1. Low Pass Filter

2. High Pass Filter
EXPERIMENT X
Aim: Verification of basic logic gates.

Components required: 2mm banana connectors, logic gates ICs, wires.

Equipment required: 5v power supply, universal workstation, bread board.

Theory: Logic gates are electronic circuits which perform logical functions on one or
more inputs to produce one output. When all the input combinations of a logic gate are
written in a series and their corresponding outputs written along them, then this input/
output combination is called Truth Table.

Procedure:

1. The VCC +5v should be connected to the IC pin 14 w.r.t Ground pin 7.

2. The inputs of the logic gate should be connected to the logic switches and its
output to the logic indicator (LED).

3. Various input combinations should be applied and output should be observed for
each one.

4. The truth table should be verified for each input/ output combination.

5. The process should be repeated for all other logic gates

Observations

For 7408 IC (AND)

For 743T IC (OR)

For 7404 IC (NOT)

For 7400 IC (NAND)

For 7486 IC (NOR)

For Half-Adder Circuit

For Full-Adder Circuit