ASSIGNMENT NO · in accordance with Ohm's law: V = IR . The resistance R is equals to the voltage drop V across the resistor divided by the current I through the resistor. The primary

Basic Electronics laboratory manual Dept of Applied sciences and Engineering

International Institute of Information Technology, Hinjawadi, Pune. Page 1

OBJECTIVE:

1. Study of passive components -

Resistors, Capacitors, Inductors and transformers

2. To Identify and understand different types of connectors, switches.

THEORY:

There are two types of components that we come across in electronics namely Active

and Passive components. Resistors, Capacitors etc., are known as passive components

because they can only attenuate the electrical voltage and signals and cannot amplify

Whereas active devices like transistors, operational amplifier (Op Amp) can amplify or

increase the amplitude and energy associated with the signals.

Passive components

Resistors Capacitors Inductors

RESISTORS

A resistor is a two-terminal electronic component designed to oppose an electric current

by producing a voltage drop between its terminals in proportion to the current, that is,

in accordance with Ohm's law: V = IR. The resistance R is equals to the voltage drop V

across the resistor divided by the current I through the resistor.

The primary characteristics of resistors are their resistance and the power they can

dissipate. Other characteristics include temperature coefficient, noise, and inductance.

Practical resistors can be made of resistive wire and various compounds and films, and

they can be integrated into hybrid and printed circuits. Size and position of leads are

relevant to equipment designers; resistors must be physically large enough not to

overheat when dissipating their power. Resistors can be broadly of two types Fixed

Resistors and Variable Resistors.

ASSIGNMENT NO.1

TITLE: STUDY OF DIFFERENT ELECTRONIC COMPONENTS

Dipak

Highlight

Dipak

Highlight



The symbols are as shown below

Fixed Resistors:

Carbon Film (5%, 10% tolerance) and Metal Film Resistors (1%,2% tolerances) and wire

wound resistors. A fixed resistor is one for which the value of its resistance is specified

and cannot be varied in general.

Resistance Value:

The resistance value is displayed using the color code (the colored bars/the colored

stripes), because the average resistor is too small to have the value printed on it with

numbers. The resistance value is a discrete value. For example, the values [1], [2.2], [4.7]

and [10] are used in a typical situation.

Colour coding:

Example 1:

(Brown=1), (Black=0), (Orange=3)

10 x 103 = 10k ohm; Tolerance (Gold) = ±5%

Fig. 1.1: Resistor

Table 1.1: Color band chart for calculating the value of resistor

Color Value Multiplier Tolerence(%)

Black 0 1 -

Brown 1 101 ±1

Red 2 102 ±2

Orange 3 103 ±0.05

Yellow 4 104 -

Green 5 105 ±0.5

Blue 6 106 ±0.25

Violet 7 107 ±0.1

Gray 8 108 -

White 9 109 -

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Gold - 10-1 ±5

Silver - 10-2 ±10

None - - ±20

Variable Resistors:

Variable resistors are adjustable by changing the position of a tapping on the resistive

element and resistors with a movable tap ("potentiometers"), either adjustable by the

user of equipment or contained within, are also used.

Resistors are used as part of electrical networks and electronic circuits. There are special

types of resistor whose resistance varies with various quantities, most of which have

names, and articles, of their own the resistance of thermistor varies greatly with

temperature, whether external or due to dissipation, so they can be used for

temperature or current sensing metal oxide varistors drop to a very low resistance

when a high voltage is applied, making them suitable for over-voltage protection the

resistance of a strain gauge varies with mechanical load; the resistance of photoresistors

varies with illumination; the resistance of a Quantum Tunnelling Composite can vary

by a factor of 1012 with mechanical pressure applied and so on.

Units:

The ohm (symbol: Ω) is a SI-driven unit of electrical resistance, named after Georg Ohm.

Letter R is used for Ohms, ‘K’ for Kilohms and ‘M’ for Megaohms and placed where the

decimal point would go.

Examples

R47 0.47 ohms

4R7 4.7 ohms

470R 470 Ohms

4K7 4.7K ohms

47K 47K ohms

47K3 47.3K ohms

470K 470K ohms

Carbon Film Resistors:

Dipak

Highlight

Dipak

Highlight



This is the most general purpose, cheap resistor. Usually the tolerance of the resistance

value is ±5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently used. The

disadvantage of using carbon film resistors is that they tend to be electrically noisy.

Fig.1.2:Carbon film resistor (CFR)

Metal film Resistors:

Metal film resistors are used when a higher tolerance (more accurate value) is needed.

Nichrome (Ni-Cr) is generally used for the material of resistor. They are much more

accurate in value than carbon film resistors. They have about ±0.05% tolerance.

Fig.1.3:Metal film resistor (MFR)

Ceramic Resistors:

Another type of resistor is the Ceramic resistor. These are wire wound resistors in a

ceramic case, strengthened with special cement. They have very high power ratings,

from 1 or 2 watts to dozens of watts. These resistors can become extremely hot when

used for high power applications, and this must be taken into account when designing

the circuit.

Fig.1.4: Ceramic resistor

Single Line Network resistor:

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Fig.1.5: Single line network resistor

Wire Wound Resistors:

There is another type of resistor called the wire wound resistor. A wire wound resistor

is made of metal resistance wire, and because of this, they can be manufactured to

precise values. Also, high-wattage resistors can be made by using a thick wire material.

Wire wound resistors cannot be used for high-frequency circuits.

Fig.1.6: Wire wound resistor

Variable Resistors:

There are two general ways in which variable resistors are used. One is the variable

resistor whose value is easily changed, like the volume adjustment of Radio. The other

is semi-fixed resistor that is not meant to be adjusted by anyone but a technician. It is

used to adjust the operating condition of the circuit by the technician.

Semi-fixed resistors are used to compensate for the inaccuracies of the resistors, and to

fine-tune a circuit. The rotation angle of the variable resistor is usually about 300

degrees. Some variable resistors must be turned many times ( multi-turn Pot) to use the

whole range of resistance they offer. This allows for very precise adjustments of their

value. These are called "Potentiometers" or "Trimmer Potentiometers” or “presets”.

Dipak

Highlight

Dipak

Highlight



Fig.1.7: Variable resistors

Light Dependent Resistors:

One type of variable resistor is the Cadmium Sulphide Photocell. It is a kind of resistor,

whose value depends on the amount of light falling on it. When in darkness its

resistance if very large and as more and more light falls on it its resistance becomes

smaller and smaller.

Fig.1.8: Light dependent resistor

Thermistors:

The resistance value of the thermistor changes according to temperature. They are used

as a temperature sensor. There are generally two types of thermistors with

• Negative Temperature Coefficient (NTC)

• Positive Temperature Coefficient (PTC)

•

Fig.1.9: Thermistor

Dipak

Highlight

Dipak

Highlight



CAPACITOR

Capacitor consists of two or more parallel conductive (metal) plates which are not

connected or touching each other, but are electrically separated either by air or by some

form of insulating material such as paper, mica, ceramic or plastic and which is

commonly called the capacitors Dielectric.

Fig.1.10: Working of capacitor

Dielectric Capacitors are usually of the variable type where a continuous variation of

capacitance is required for tuning transmitters, receivers and transistor radios. The

position of the moving plates with respect to the fixed plates determines the overall

capacitance value. The capacitance is generally at maximum when the two sets of plates

are fully meshed together. High voltage type tuning capacitors have relatively large

spacings or air-gaps between the plates with breakdown voltages reaching many

thousands of volts.

Variable Capacitors symbol:

Fig.1.11: Trimmer capacitor

As well as the continuously variable types, preset type variable capacitors are also

available called Trimmers. These are generally small devices that can be adjusted or

Dipak

Highlight

Dipak

Highlight



"pre-set" to a particular capacitance value with the aid of a small screwdriver and are

available in very small capacitances of 500pF or less and are non-polarized.

Ceramic Capacitors:

Ceramic Capacitors or Disc Capacitors are made by coating two sides of a small

ceramic disc with silver and are then stacked together to make a capacitor. For very low

capacitance values a single ceramic disc of about 3-6mm is used. Ceramic capacitors

have a high dielectric constant (High-K) and are available so that relatively high

capacitances can be obtained in a small physical size.

Fig. 1.12: Ceramic capacitor

They exhibit large non-linear changes in capacitance against temperature and as a result

are used as de-coupling or by-pass capacitors as they are also non-polarized devices.

Ceramic capacitors have values ranging from a few Picofarads to one or two

microfarads but their voltage ratings are generally quite low.

Ceramic types of capacitors generally have a 3-digit code printed onto their body to

identify their capacitance value in picofarads. Generally the first two digits indicate the

capacitors value and the third digit indicates the number of zero's to be added. For

example, a ceramic disc capacitor with the markings 103 would indicate 10 and 3 zero's

in pico-farads which is equivalent to 10,000 pF or 10nF. Letter codes are sometimes used

to indicate their tolerance value such as: J = 5%, K = 10% or M = 20% etc.

ELECTROLYTIC CAPACITORS

Electrolytic Capacitors are generally used when very large capacitance values are

required. This insulating layer is so thin that it is possible to make capacitors with a

large value of capacitance for a small physical size as the distance between the plates, d

is very small.

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Fig. 1.13: Electrolytic Capacitor

The majority of electrolytic types of capacitors are Polarized, that is the DC voltage

applied to the capacitor terminals must be of the correct polarity, i.e. positive to the

positive terminal and negative to the negative terminal as an incorrect polarization will

break down the insulating oxide layer and permanent damage may result. All polarized

electrolytic capacitors have their polarity clearly marked with a negative sign to indicate

the negative terminal and this polarity must be followed. Electrolytic Capacitors are

generally used in DC power supply circuits due to their large capacitances and small

size to help reduce the ripple voltage or for coupling and decoupling applications. One

main disadvantage of electrolytic capacitors is their relatively low voltage rating and

due to the polarization of electrolytic capacitors. Electrolytic generally come in two

basic forms; Aluminum Electrolytic Capacitors and Tantalum Electrolytic Capacitors.

CAPACITOR CHARACTERISTICS

Fig.1.14: Capacitor characteristics



CAPACITOR COLOUR CODE TABLE:

Table 1.2 Capacitor color code table

Colour Digit

A

Digit

B

Multiplier

D

Tolerance

(T) > 10pf

Tolerance

(T) < 10pf

Temperature

Coefficient

(TC)

Black 0 0 x1 ± 20% ± 2.0pF

Brown 1 1 x10 ± 1% ± 0.1pF -33x10-6

Red 2 2 x100 ± 2% ± 0.25pF -75x10-6

Orange 3 3 x1,000 ± 3% -150x10-6

Yellow 4 4 x10,000 ± 4% -220x10-6

Green 5 5 x100,000 ± 5% ± 0.5pF -330x10-6

Blue 6 6 x1,000,000 -470x10-6

Violet 7 7 -750x10-6

Grey 8 8 x0.01 +80%,-

20%

White 9 9 x0.1 ± 10% ± 1.0pF

Gold x0.1 ± 5%

Silver x0.01 ± 10%

CAPACITOR VOLTAGE COLOUR CODE TABLE:

Table 1.3 Capacitor voltage color code table

Colour Voltage Rating (V)

Type J Type K Type L Type M Type N

Black 4 100 10 10

Brown 6 200 100 1.6

Red 10 300 250 4 35

Orange 15 400 40

Dipak

Highlight

Dipak

Highlight



Yellow 20 500 400 6.3 6

Green 25 600 16 15

Blue 35 700 630 20

Violet 50 800

Grey 900 25 25

White 3 1000 2.5 3

Gold 2000

Silver

Capacitor Voltage Reference

• Type J : Dipped Tantalum Capacitors.

• Type K : Mica Capacitors.

• Type L : Polyester/Polystyrene Capacitors.

• Type M : Electrolytic 4 Band Capacitors.

• Type N : Electrolytic 3 Band Capacitors.

Metalized Polyester Capacitor

Disc & Ceramic Capacitor

Dipak

Highlight



Fig. 1.15: capacitor value identification

Capacitor Tolerance Letter Codes Table

Table1.4: Capacitor tolerance letter code table

Letter B C D F G J K M Z

Tolerance C <10pF ±pF 0.1 0.25 0.5 1 2

C >10pF ±% 0.5 1 2 5 10 20 +80-20

Consider the capacitor below:

The capacitor on the left is of a ceramic disc type capacitor

that has the code 473J printed onto its body. Then the 4 = 1st

digit, the 7 = 2nd digit,

the 3 is the multiplier in pico-Farads, pF and the letter J is the

tolerance and this translates to:

47pF * 1,000 (3 zero's) = 47,000 pF , 47nF or 0.047 uF

the J indicates a tolerance of +/- 5%

Fig. 1.16: capacitor code

Mica Capacitors:

These capacitors use Mica for the dielectric. Mica capacitors have good stability because

their temperature coefficient is small. Because their frequency characteristic is excellent,

they are used for resonance circuits, and high frequency filters. They have very good

insulation, and so can be utilized in high voltage circuits. It was often used for vacuum

tube style radio transmitters, etc. Mica capacitors do not have high values of

capacitance, and they can be relatively expensive. Pictures shown are "Dipped mica

capacitors.” These can handle upto 500 volts. These capacitors have no polarity.

Fig.1.17: mica capacitor

Dipak

Highlight



Variable capacitors:

Variable capacitors are used for adjustment of frequency mainly. The value of the

capacitor can be affected by the capacitance of the screwdriver we use so we have to use

a special screwdriver.

There are different colors, as well. Blue: 7pF (2 -9), white: 10pF (3 -15), green: 30pF (5 -

35), brown: 60pF (8 -72). These capacitors are used for radio tuners. The capacitance is

varied by turning the spindle which changes the area between the plates.

Fig.1.18: variable capacitors

APPLICATIONS:

1) Energy storage

2) Pulsed power and weapons

3) Power conditioning

4) Power factor correction

5) Supression and coupling

6) Noise filters and snubbers

7) Motor starters

8) Signal processing

9) Tuned circuits

INDUCTORS:

Fig.1.19: Types of inductor

An inductor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it. An inductor's ability to store magnetic

energy is measured by its inductance, in units of Henries.

APPLICATIONS:

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



1) Inductors are used extensively in analog circuits and signal processing.

2) An inductor is used as the energy storage device in some switched-mode power

supplies.

3) Inductors are also employed in electrical transmission systems, where they are used

to depress voltages from lightning strikes and to limit switching currents and fault

current. In this field, they are more commonly referred to as reactors.

Fig.1.20: simple transformer

A transformer is a device that transfers electrical energy from one circuit to another

through inductively coupled electrical conductors. A changing current in the first circuit

(the primary) creates a changing magnetic field. This changing magnetic field induces a

changing voltage in the second circuit (the secondary). This effect is called mutual

induction.

If a load is connected to the secondary circuit, electric charge will flow in the secondary

winding of the transformer and transfer energy from the primary circuit to the load. In

an ideal transformer, the induced voltage in the secondary winding (VS) is a fraction of

the primary voltage (VP) and is given by the ratio of the number of secondary turns to

the number of primary turns:

By appropriate selection of the numbers of turns, a transformer thus allows an

alternating voltage to be stepped up — by making NS more than NP — or stepped

down, by making it less. Transformers are some of the most efficient electrical

'machines', with some large units able to transfer 99.75% of their input power to their

output. Transformers come in a range of sizes from a thumbnail-sized coupling

transformer hidden inside a stage microphone to huge units weighing hundreds of tons

used to interconnect portions of national power grids.

APPLICATIONS:

Dipak

Highlight

Dipak

Highlight



A major application of transformers is to increase voltage before transmitting electrical

energy over long distances through wires. Wires have resistance and so dissipate

electrical energy at a rate proportional to the square of the current through the wire. By

transforming electrical power to a high-voltage (and therefore low-current) form for

transmission and back again afterwards, transformers enable economic transmission of

power over long distances. Transformers are also used extensively in electronic

products to step down the supply voltage to a level suitable for the low voltage circuits

they contain. The transformer also electrically isolates the end user from contact with

the supply voltage.

Signal and audio transformers are used to couple stages of amplifiers and to match

devices such as microphones and recor d player cartridges to the input impedance of

amplifiers. Audio transformers allowed telephone circuits to carry on a two-way

conversation over a single pair of wires. Transformers are also used when it is necessary

to couple a differential-mode signal to a ground-referenced signal, and for isolation

between external cables and internal circuits.

CONNECTORS:

An electrical connector is a conductive device for joining electrical circuits together.

The connection may be temporary, as for portable equipment, or may require a tool for

assembly and removal, or may be a permanent electrical joint between two wires or

devices. Connectors may join two lengths of flexible wire or cable, or may connect a

wire or cable to an electrical terminal.

Properties of Electrical connector:

An ideal electrical connector would have a low contact resistance and high insulation

value. It would be resistant to vibration, water, oil, and pressure. It would be easily

mated/unmated, unambiguously preserve the orientation of connected circuits,

reliable, carry one or multiple circuits. Desirable properties for a connector also include

easy identification, compact snize, rugged construction, durability (capable of many

connect/disconnect cycles), rapid assembly, simple tooling, and low cost. No single

connector has all the ideal properties.

Power Connectors:

Domestic AC power plugs and sockets, NEMA connectors, Industrial and multiphase

power plugs and sockets for discussions of connectors used for electric power. Power

connectors must protect people from accidental contact with energized conductors.

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Power connectors often include a safety ground connection as well as the power

conductors. In larger sizes, these connectors must also safely contain any arc produced

when an energized circuit is disconnected or may require interlocking to prevent

opening a live circuit.

Fig.1.21: Power connectors

Above figure shows a common type of 115 VAC receptacle used to connect the power

cord to things such as personal computers and test equipment and a "Jones" or "Cinch-

Jones" connector. These have been around for decades, and are used in applications

such as supplying power to a DC motor.

Audio Connectors:

Fig. below shows what is commonly called an "RCA" plug and jack. They are two-

conductor connectors typically used with shielded cable. They are used in applications

such as connecting microphones and small speakers to audio amplifiers.

Fig. 1.22: Audio connectors

Modular telephone Connectors:

These are used with UTP (unshielded twisted pair) cables. Fig. shows an RJ11 connector

commonly used with 4-wire telephone cables. An RJ12 connector is the same size but

used with 6-wire cable. Fig. below shows an RJ45 connector used with 8-wire local area

network (LAN) cables.

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Fig.1.23: modular telephone connectors

BNC and UHF connectors

Fig. below shows a BNC cable commonly used with shielded cable, such as RG58,

carrying RF signals. Exactly what BNC stands for is unclear, but most people think the

B is for bayonet because of the way the connector locks on to the receptacle. BNC

connectors are common on electronics test equipment such as oscilloscopes.

Fig.1.24: BNC and UHF connectors

Fig. below, shows a UHF connector (UHF stands for Ultra High Frequency). Like the

BNC connector, it is used on coaxial cables carrying RF signals. It can be used on thicker

cable such as RG8. A UHF connector is threaded to screw onto the receptacle.

Fig. 1.25

D-Shell connectors:

Fig. 1.26 (A) Fig. 1.26 (B)

Dipak

Highlight



Fig. (A) shows a DB9 connector. Fig. (B) shows a so-called Centronics connector

commonly used for the printer port of a PC.

Fig. 1.27: Edge Connectors:

Insulation Displacement Connectors (IDCs)

Fig.1.28: (A) (B) (C)

Fig. above shows the types of connectors used with ribbon cables. Fig. A is a "DIP"

connector, which can plug into a standard IC DIP socket. The connector of Fig. B mates

a "header", which has pins on 0.1" centers and is common on circuit boards. The

connector of Fig. C is a "shrouded" header.

Plug and Socket Connectors:

Fig.:1.29 A male plug made by Amphenol

Plug and socket connectors are usually made up of a male plug and a female socket,

although hermaphroditic connectors exist, such as the original IBM token ring LAN



connector. Plugs generally have one or more pins or prongs that are inserted into

openings in the mating socket. The connection between the mating metal parts must be

sufficiently tight to make a good electrical connection and complete the circuit. When

working with multi-pin connectors, it is helpful to have a pin out diagram to identify

the wire or circuit node connected to each pin.

Fig.1.30: 8P8C connector crimped to cable

8P8C is short for "eight positions, eight conductors", and so an 8P8C modular connector

(plug or jack) is a modular connector with eight positions, all containing conductors.

D-subminiature connectors:

Fig.1.31: A male DE-9 plug.

The D-subminiature electrical connector is commonly used for the RS 232 serial port on

modems and IBM compatible computers. The D-subminiature connector is used in

many different applications, for computers, telecommunications, and test and

measurement instruments. A few examples are monitors (MGA, CGA, EGA), the

Commodore 64, MSX, Apple II, Amiga and Atari joysticks and mice, and game consoles

such as Atari, Sega and Amiga.

USB Connectors

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Fig. 1.32: A male USB series A plug

The Universal Serial Bus is a serial bus standard to interface devices, founded in 1996.

It is currently widely used among PCs, Apple Macintosh and many other devices. There

are several types of USB connectors, and some have been added as the specification has

progressed. The most commonly used is the (male) series "A" plug on peripherals, when

the cable is fixed to the peripheral. If there is no cable fixed to the peripheral, the

peripheral always needs to have a USB "B" socket. In this case a USB "A" plug to a USB

"B" plug cable would be needed. USB "A" sockets are always used on the host PC and

the USB "B" sockets on the peripherals. It is a 4-pin connector, surrounded by a shield.

There are several other connectors in use, the mini-A, mini- B and mini-AB plug and

socket (added in the On-The-Go Supplement to the USB 2.0 Specification).

SWITCHES:

In electronics, a switch is an electrical component which can break an electrical circuit,

interrupting the current or diverting it from one conductor to another. The most

familiar form of switch is a manually operated electromechanical device with one or

more sets of electrical contacts. Each set of contacts can be in one of two states: either

'closed' meaning the contacts are touching and electricity can flow between them, or

'open', meaning the contacts are separated and nonconducting.

Fig. 1.33: Three pushbutton switches. Major scale is inches

There are three important features to consider when selecting a switch:

• Contacts (e.g. single pole, double throw)

• Ratings (maximum voltage and current)

• Method of Operation (toggle, slide, key etc.)

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Switch Contacts

Several terms are used to describe switch contacts:

• Pole - number of switch contact sets.

• Throw - number of conducting positions, single or double.

• Way - number of conducting positions, three or more.

• Momentary - switch returns to its normal position when released.

• Open - off position, contacts not conducting.

• Closed - on position, contacts conducting, there may be several on positions.

For example: the simplest on-off switch has one set of contacts (single pole) and one

switching position which conducts (single throw). The switch mechanism has two

positions: open (off) and closed (on), but it is called 'single throw' because only one

position conducts.

Switch Contact Ratings

Switch contacts are rated with a maximum voltage and current, and there may be

different ratings for AC and DC. The AC values are higher because the current falls to

zero many times each second and an arc is less likely to form across the switch contacts.

For low voltage electronics projects the voltage rating will not matter, but you may need

to check the current rating. The maximum current is less for inductive loads (coils and

motors) because they cause more sparking at the contacts when switched off.

Standard Switches

Type of Switch Circuit Symbol Example

ON-OFF

Single Pole, Single Throw = SPST

A simple on-off switch. This type can be

used to switch the power supply to a

circuit. When used with mains

electricity this type of switch must be in

the live wire, but it is better to use a

DPST switch to isolate both

SPST toggle switch

(ON)-OFF

Push-to-make = SPST Momentary

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



A push-to-make switch returns to its

normally open (off) position when you

release the button, this is shown by the

brackets around ON. This is the

standard doorbell switch.

Push-to-make switch

ON-(OFF)

Push-to-break = SPST Momentary

A push-to-break switch returns to its

normally closed (on) position when you

release the button.

Push-to-break switch

ON-ON

Single Pole, Double Throw = SPDT

This switch can be on in both positions,

switching on a separate device in each

case. It is often called a changeover

switch. For example, a SPDT switch can

be used to switch on a red lamp in one

position and a green lamp in the other

position.

ON-OFF-ON

SPDT Centre Off

A special version of the standard SPDT

switch. It has a third switching position

in the centre which is off. Momentary

(ON)-OFF-(ON) versions are also

available where the switch returns to

the central off position when released.

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Dual ON-OFF

Double Pole, Single Throw = DPST

A pair of on-off switches which operate

together (shown by the dotted line in

the circuit symbol).A DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections.

DPST rocker switch

Dual ON-ON

Double Pole, Double Throw = DPDT

A pair of on-on switches which operate

together (shown by the dotted line in

the circuit symbol).

A DPDT switch can be wired up as a

reversing switch for a motor as shown

in the diagram.

ON-OFF-ON

DPDT Centre Off

It has a third switching position in the

centre which is off. This can be very

useful for motor control because you

have forward, off and reverse positions.

.

DPDT slide switch

Wiring for Reversing

Switch

SPECIAL SWITCHES

Type of Switch Example

Push-Push Switch (e.g. SPST = ON-OFF)

This looks like a momentary action push switch but it is a

standard on-off switch: push once to switch on, push

again to switch off. This is called a latching action.

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Micro switch (usually SPDT = ON-ON)

Micro switches are designed to switch fully open or closed

in response to small movements. They are available with

levers and rollers attached.

Key switch

A key operated switch. The example shown is SPST.

Tilt Switch (SPST)

Tilt switches contain a conductive liquid and when tilted

this bridges the contacts inside, closing the switch. They

can be used as a sensor to detect the position of an object.

Some tilt switches contain mercury which is poisonous.

Reed Switch (usually SPST)

The contacts of a reed switch are closed by bringing a

small magnet near the switch. They are used in security

circuits, for example to check that doors are closed.

Standard reed switches are SPST (simple on-off) but SPDT

(changeover) versions are also available.

DIP Switch (DIP = Dual In-line Parallel)

This is a set of miniature SPST on-off switches, the

example shown has 8 switches. The package is the same

size as a standard DIL (Dual In-Line) integrated circuit.

This type of switch is used to set up circuits, e.g. setting

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



the code of a remote control.

Multi-pole Switch

The picture shows a 6-pole double throw switch, also

known as a 6-pole changeover switch. It can be set to have

momentary or latching action. Latching action means it

behaves as a push-push switch, push once for the first

position, push again for the second position etc.

Multi-way Switch

Multi-way switches have 3 or more conducting positions.

They may have several poles (contact sets). A popular

type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way.

The number of ways (switch positions) may be reduced by

adjusting a stop under the fixing nut. For example if you

need a 2-pole 5-way switch you can buy the 2-pole 6-way

version and adjust the stop.

Contrast this multi-way switch (many switch positions)

with the multi-pole switch (many contact sets) described

above.

Multi-way rotary switch

1-pole 4-way switch

symbol

CONCLUSION:

Dipak

Highlight

Dipak

Highlight



OBJECTIVE:

1. To study different controls of DMM and measurement of parameters like AC

and DC voltage, current

2. To study controls of CRO, Measurement of frequency, phase, AC & DC Voltages.

3. To study various controls of signal generator.

THEORY:

DMM: A multimeter or a multitester, also known as a volt/ohm meter or VOM, is an

electronic measuring instrument that combines several functions in one unit. A

standard multimeter may include features such as the ability to measure voltage,

current and resistance.

Fig. 2.1 : Front panel of DMM

ASSIGNMENT NO. 2

TITLE: STUDY OF DIFFERENT ELECTRONIC MEASURING

INSTRUMENTS

Dipak

Highlight



A multimeter can be a hand-held device useful for basic fault finding and field service

work or a bench instrument which can measure to a very high degree of accuracy. They

can be used to troubleshoot electrical problems in industrial and household devices

such as batteries, motor controls, appliances, power supplies, and wiring systems

PROCEDURE:

MEASUREMENT OF AC VOLTAGE, DC VOLTAGE & DC CURRENT:

1) Connect red test lead to “V”input terminal and black test lead to“COM” input

terminal.

2) Set Function/Range switch to desired voltage type (DC or AC) and range. If

magnitude of voltage is not known, set switch to the highest range and reduce until

a satisfactory reading is obtained.

3) Turn off power to the device or circuit being tested.

4) Connect test leads to the device or circuit being measured.

5) Turn on power to the device or circuit being measured. Voltage value will appear on

the digital display along with the voltage polarity.

6) Turn off power to the device or circuit being tested prior to disconnecting test leads.

Current Measurement:

1) Connect red test lead to the “mA” input terminal for current measurements up to

200 milliamperes. Connect black lead to the COM input terminal.

2) Set Function/Range switch to desired current type (DC or AC) and range. If

magnitude of current is not known, set switch to the highest range and reduce until

a satisfactory reading is obtained.

3) Turn off power to the device or circuit being tested.

4) Open the circuit in which current is to be measured. Now securely connect test leads

in series with the load in which current is to be measured.

5) Turn on power to the device or circuit being tested.

6) Read current value on digital display.

7) Turn off all power to the device or circuit being tested.

8) Disconnect test leads from circuit and reconnect circuit that was being tested.

9) For current measurement of 200mA or greater, connect the red test lead to “20 A”

input terminal & black test lest lead to the “COM” input terminal.

The central knob has lots of positions and you must choose which one is appropriate

for the measurement you want to make.If the meter is switched to 20 V DC,for

Dipak

Highlight



example,then 20 V is the maximum voltage which can be measured,this is

sometimes called 20 V fsd, fsd is full scale deflection.

1. Additionally, multimeter may also measure:

2. Capacitance in farads

3. Frequency in Hertz

4. Duty cycle as a percentage.

5. Temperature in degree Celsius or Farenheit.

6. Conductance in Siemens

7. Inductance in henry

8. Continuity that beeps when a circuit conducts.

9. Diodes and transistor testing

For safety reasons, you must NEVER connect a multimeter to the mains supply.

Observation Table:

1. Resistors (fixed value)

By using color code Using DMM

2. Variable resistors:

Theoretical value of Potentiometer-

Min value-

Max value-

3. Capacitor (Fixed value):

By using color code

And value on

capacitor

Using DMM

Dipak

Highlight



4. AC voltage and current:

Reading on the

CRO Vpp

Vrms by

calculation

Using DMM

5. DC voltage and current:

Reading on DC power

supply

Using

DMM

DC current

theoretical

Measured Dc

current

6. Diode testing:

7. Transistor testing:

CATHODE RAY OSCILLOSCOPE (CRO):

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of

frequencies. Its reliability, stability, and ease of operation make it suitable as a general

purpose laboratory instrument. The heart of the CRO is a cathode-ray tube shown

schematically in Fig.. 1. The cathode ray is a beam of electrons which are emitted by the

heated cathode (negative electrode) and accelerated toward the fluorescent screen. The

assembly of the cathode, intensity grid, focus grid, and accelerating anode (positive

electrode) is called an electron gun. Its purpose is to generate the electron beam and

control its intensity and focus. Between the electron gun and the fluorescent screen are

two pair of metal plates - one oriented to provide horizontal deflection of the beam and

one pair oriented to give vertical deflection to the beam. These plates are thus referred to

as the horizontal and vertical deflection plates. The combination of these two deflections

allows the beam to reach any portion of the fluorescent screen. Wherever the electron

beam hits the screen, the phosphor is excited and light is emitted from that point. This

Dipak

Highlight



conversion of electron energy into light allows us to write with points or lines of light on

an otherwise darkened screen.

Fig. 2.2: Front panel of CRO

As you can see, the screen of this oscilloscope has 8 squares or divisions on the vertical

axis, and 10 squares on divisions on the horizontal axis. Usually, these squares are 1 cm

in each direction.

FRONT PANEL CONTROLS

1. POWER ‘On/Off’ : Rocker switch for supplying power to instrument.

2. X10 : Switch when pushed gives 10 times magnification of the

X signal.

3. FOCUS : Controls the sharpness of the trace.

4. XY : Switch when pressd cut off the time base & allows access to

the external horizontal signal to be fed through CH2(used

for X-Y display).

5. CH1/2, Trig ½ : Switch selects channel & trigger source(released CH1

& pressed CH2)

6. Ext : Switch when pressed allows external triggering signal to be

fed from the socket marked Trigger input (24).

7. Alt : Selects alternate trigger mode from CH1 & CH2.In this

mode both the signals are synchronized.

Dipak

Highlight



8. Slope (+/-) : Switch selects the slope of triggering, whether positive

going or negative going.

9. Auto/level : Selects Auto/level position.Auto is used to get trace when

no signal is fed at the input. In Level position the trigger

level can be varied from the positive peak to negative peak

with level control.

10. Level : Controls the trigger level from peak to peak amplitude of

signal.

11. Component tester : Switch when pressed starts CT operation.

12. X shift : Controls horizontal position of the trace.

13. TB Var : Controls the time speed in between two steps of the

Time/Div switch. For calibration put this pot fully

anticlockwise at Cal position.

14. TR : Trace rotation controls the alignment of the trace with

graticule (screw driver adjustment).

15. Cal out : Socket provided for square wave output 200mV used for

probe compensation and checking vertical sensitivity,etc.

16. Volts/div. : Switch selects Volt/Div.step for CH1 & CH2

17. CH1(Y) & CH2(X) : BNC connectors serve as input connection for CH1 & CH2

input connector also serves as horizontal external input.

18. Time/Div. Switch selects Time/Div. steps

19. Component tester input: To test any componenet in the CT mode, put one test probe

in this socket and connect the other test prod in ground

socket.

20. Trigger Input : Socket provided to feed external trigger signal in External

Trigger mode.

21. Invert CH2 : Switch when pressed invert polarity of CH2.

22. Digital Readout : LCD window for displaying Digital Readout for Volt/Div.

& Time/Div. settings.

23. Y shift 1 & 2 : Controls provided for verticak deflection of trace for each

channel.

24. AC/ DC /GND : Input coupling switch for each channel. In AC the signal is

coupled through 0.1MFD capacitor.

25. Alt / Chop/Add : Switch Selects alternate or chopped in Dual mode.If Mono

is selected then this switch enables addition or subtraction of

channel i.e.CH1 ± CH2.



26. Intensity : Controls the brightness of the trace.

27. Mono/dual : Switch selects Mono or Dual trace operation.

Measurement of Different Parameters

1) Frequency Measurement:

1. Connect the signal from the signal generator to the Y-input/X-input.

2. Adjust the time base generator switch (time/div) to get a steady pattern of

the signal on the CRO screen.

3. Measure the time interval T for one cycle.

4. Determine the frequency F of the signal (F=l/T )

5. Repeat the same procedure for different frequencies.

2) DC voltage measurement:

1. Adjust the beam to certain reference level

2. Keep AC/DC selector switch on DC position.

3. Apply test voltage to CRO input.

4. Measure the shift of beam from reference level.

6. Calculate D.C. Voltage No. of divisions on y – axis x Volts/Div.

7. Note down the reading.

3) AC voltage measurement:

1. Keep AC/DC selector switch on AC position.

2. Apply AC voltage from signal generator to CRO input.

3. Measure no. of divisions on y – axis.

4. Calculate A.C. Voltage No. of divisions on y – axis x Volts/Div.

4) Phase measurement:

1. Phase difference α between two signals (same frequency) is obtained by feeding

the signals to two inputs X and Y of a dual trace CRO.

2. Set the CRO to XY mode. Keep Dual /Mono on Mono Position.

3. A Lissajous pattern is produced on the screen when two sine wave voltages are

applied simultaneously to both pairs of deflection plates of a CRO

4. The phase difference between two sinusoidal signals of same frequency can be

Calculated from the amplitudes Y1 and Y2 of the Lissajous pattern. Phase

difference is given by α = Sin-1 (Y1/Y2)

Dipak

Highlight



(a) (b)

Fig.2.3: a) Phase difference between two signals

b) Lissajous pattern

OBSERVATION TABLE:

PHASE MEASUREMENT

Function

Vertical

Division

(a)

Volt/div

(b)

Amplitude

(p-p)

V=a*b

Horizontal

Div (c)

Time/div

(d)

Time

T =c*d

Freq.

F=1/T

Sine

wave

Square

Wave

Sr. No Y1 = Y2 =

Phase Angle

α = Sin-1 (Y1/Y2)

(degree)

1

2

Dipak

Highlight

Dipak

Highlight

Dipak

Highlight



Draw observed waveforms:

Sine wave: (Amplitude: Frequency: )

Square wave: (Amplitude: Frequency: )

Questions:

1. What is the use of C.R.O.?

2. What is the highest frequency that can be measured by C.R.O. available in your

laboratory?

3. What is the highest voltage that can be measured by C.R.O. available in your

laboratory?

4. What you will do to measure voltage which is greater than voltage limit of the

C.R.O.?

5. Why AC/DC input coupling push-button switch is given?

6. What do you mean by dual channel C.R.O.?

7. How to test whether CRO probe is in working condition or not?

Dipak

Highlight



Component Tester

Oscilloscope comes with an additional facility, built-in Components tester. This allows

passive and active components like resistors, capacitors, inductors, transformer, silicon

or germanium diodes, Zener diodes, tunnel diodes, schottky diodes, transistors, JFETs,

MOSFETs, UJTs, SCRs, TRIACs, and even linear and digital ICs to be tested while still

in circuit.

Just push in the CT switch, plug in two test prods (supplied with instrument) one at the

Banana socket marked CT and the other at the ground socket. A horizontal line about 5

to 6 cms will be seen. On shorting the two tests prod tips a vertical line is seen. Connect

the component under test across the probs. Some typical test patterns are shown on the

following figure. Only remember to keep the scope in the "CH 1" operating mode and

Ground the input of CH 1.



SIGNAL GENERATOR:

Signal Generator provides various signals like sine wave, square wave for

different test circuits. Its frequency range varies from 1Hz to 1MHz with adjustable

amplitude, for sine wave 0 to 10V, for square wave 0 to 20V peak to peak. The output

impedance of generator is 600Ω at output level of 1V & below. The front panel of signal

generator is shown in Fig. 2.4

Fig.2.4: Front panel controls

FRONT PANEL CONTROLS:

1. Power ‘On/Off ‘ : At the rear side of the instrument, Power can be Switched

On or Off.

2. LCD Display : 16x2 Character bright back lit Liquid Crystal Display.

3. Frequency : Used for selection of frequency range in seven decade

Steps.

4. Function : Used for selection of Particular waveform.

5. Attenuation : Attenuation in two steps, ±20 dB and Variable attenuation

From 0 to 20dB Total of 60 dB.

6. FG/ FC : Used for selection of Function Generator or frequency

counter mode.

7. FM AMPL (adjusting knob) : Attenuation of input voltage for FM-input. This

Permits the user to change the sweep width.

8. Dc Offset (adjusting knob) : Adjustment of the positive or negative offset voltage.

This DC voltage can be superimposed on the output signal.

9. Trigger Variable : When trigger output is selected in CMOS output can be set

with Variable, to approximately 15 Vpp.

10. Frequency Variable(adjusting knob) : Continuous and linear frequency adjustment

Dipak

Highlight



From 0.1 Hz to 1 MHz in seven decade steps, selected with

frequency range.

11. Amplitude Variable : Continuous adjustment of the output amplitude from 22n

Vpp - 30 Vpp.

12. Output (BNC connector) : The output impedence is 50Ω/600 Ω switch selectable.

Maximum output amplitude is 30Vpp(open-circuit) or 15

Vpp when terminated with 50 Ω.

13. 50 Ω / 600 Ω : Push button when pressed, selects 600 Ω else 50 Ω.

14. Trigger Output (BNC connector) : This output supplies a square wave signal in

Synchronous with the output signal. It is switch selectable

TTL/CMOS and has a duty –factor of approximately 50%.

15. TTL/CMOS : Push button when pressed, selects CMOS else TTL.

16. FM Input (BNC Connector) : Applying a DC voltage to this input will vary the

oscillator frequency linearly to maximum 1:100. The

maximum allowable input voltage is +30 Vpp.

17. External counter(BNC Connector) : Input BNC connector for measuring the

frequency of external signal when external counter mode is

selected by Individual key(6) on LCD Screen.

CONCLUSION:

Dipak

Highlight



OBJECTIVE: For a given Regulated power supply circuit with bridge rectifier,

capacitor filter and three terminal regulator:

1. Identify pins of rectifier Diode (such as 1N4001) and study of its data sheet

specifications.

2. Identify pins of three pin regulator (such as LM 78XX or 79XX) and study of its

data sheet specifications.

3. To measure voltage and observe waveform at transformer secondary, output of

Bridge rectifier, output of regulator.

THEORY:

The p-n junction forms a popular device called p-n junction semiconductor diode. The

p-n junction has two terminals called electrodes, one each from p-region and n-region.

A rectifier is a device which converts A.C. voltage to pulsating D.C. voltage using one

or more diodes. The p-n junction diode conducts only in one direction i.e. when

forward biased and does not conduct when reverse biased. The rectifiers are broadly

classified ad half wave rectifier and full wave rectifier. The bridge rectifier is essentially

a full wave rectifier using 4 diodes forming the four arms of an electric bridge. To one

diagonal of the bridge the a.c. voltage is applied through a transformer and the rectified

voltage is taken from the other diagonal of the bridge.

It has been seen that the output of a rectifier is not a pure d.c, but it contains

fluctuations or ripple, which are undesired. To minimize the ripple content in the

output, filters are used. The filter is connected between the rectifier and the load. Ideally

the output of the filter should be pure d.c., but practically the filter circuits will try to

minimize the ripple at the output as far as possible. Two components can be used as

filters: inductors and capacitors because these components have different impedences

for a.c and d.c.. After the filters a regulator circuit is used which not only makes the d.c.

voltage smooth and almost ripple free but it also keeps the d.c output voltage constant

though input voltage varies under certain conditions.

1N4007: A diode is also called as a rectifier as it converts an alternating voltage into a

pulsating d.c. voltage. The 1N4007 is a semiconductor diode as shown with two

terminals called as anode and cathode. The terminal with a silver ring is the cathode

whereas the other terminal is the anode.

ASSIGNMENT NO. 3

TITLE: STUDY OF REGULATED POWER SUPPLY



Fig. 3.1: 1N4001 diode

Three Pin regulator ICs:

IC 78XX Series provides a fixed positive output voltage. The last two digits in the part

number indicates the D.C. output voltage. This Series provides fixed regulated voltages

from +5V to +24 V.

IC 79XX Series provides a fixed negative output voltage. This series provides fixed

regulated voltages from -5V to -24 V.

Fig.3.2

IC 7805: The 7805 regulator IC is as shown in the following Fig.. It is a three pin IC with

pin no 1 as input, 2 as ground and 3 as the regulated output.

IC 7905: The 7905 regulator IC is as shown in the following Fig.. It is a three pin IC with

pin no. 1 as Ground,2 as Input and 3 as the regulated output.

Fig. 3.3



CIRCUIT DIAGRAM:

Fig. 3.4: Circuit diagram of a power supply

PROCEDURE:

1. Trace the board as per the circuit diagram.

2. Note down the component values and device no.

3. Make the connection as per the circuit diagram.

4. Study the specifications of the diode 1N4001 from the given datasheet.

5. Study the specifications of the three pin regulator IC 7805 from the given

datasheet.

6. Measure voltage and observe the waveforms at:

i) Transformer secondary ii) output of bridge rectifier iii) output of regulator

OBSERVATIONS:

WAVEFORMS:

Note: Students are requested to draw the waveforms on the graph paper.

QUESTIONS:

1. What do you understand by regulated power supply? Draw the block diagram

of such a supply.

2. Write a short note on the need for regulated power supply.

3. What are the limitations of unregulated power supply?

4. How can you improve the regulation of an ordinary power supply?

5. Define Ripple factor?

6. What causes the ripple voltage on the output of a capacitor –input filter?

7. What is the difference between Line regulation and load regulation?

8. Draw the output waveforms at each stage in power supply design.

CONCLUSION:



OBJECTIVE: For a given BJT CE Amplifier circuit

1) Identify pins of a BJT (such as BC 547) and study of its data sheet specifications.

2) To measure voltages and observe waveforms at input and output terminals of

single stage BJT Common Emitter amplifier circuit.

3) Calculate voltage gain of the amplifier.

THEORY:

A transistor is a semiconductor device that can amplify electronic signals. It is a three

terminal device: emitter, base and collector and can be operated in one of the three

configurations namely common base, common collector and common emitter.

According to the configuration it can be used for voltage as well as current

amplification. The input signal of small amplitude is applied at the base to get the

magnified output signal at the collector. The amplification in the transistor is achieved

by passing input current signal from a low resistance to a region of high resistance. This

concept of transfer of resistance has given the name TRANSfer-resiISTOR

(TRANSISTOR). There are two types of transistors: Unipolar Junction transistors and

Bipolar Junction Transistor. In bipolar transistor, the current conduction is only due to

one type of carriers-majority carriers whereas in a bipolar junction transistor the

conduction is because of both types of carriers-electron and holes. The common emitter

configuration is widely used in amplifier circuits. This is because the CE configuration

is the only configuration which provides both voltage as well as current gain greater

than unity.

ASSIGNMENT NO. 4

TITLE: STUDY OF SINGLE STAGE BJT COMMON EMITTER

AMPLIFIER CIRCUIT



The BC 547 is a general purpose NPN transistor with its terminal as shown which can

be used for applications such as amplifiers and switch.

Fig. 4.1: Transistor BC 547

CIRCUIT DIAGRAM:

Fig. 4.2: Circuit diagram of CE amplifier

APPARATUS: Circuit board, Signal generator, CRO, CRO probes, connecting wires,

connecting wires, Dual DC power supply etc.

PROCEDURE:



3. Make the connection as per the circuit diagram for CE configuration.

4. Apply sinusoidal input signal of 1 kHz frequency and 10 mVp-p amplitude.



5. Measure the output voltage (Vo) on CRO. Draw input output waveforms on

graph paper.

6. Now vary the input signal amplitude to 20mV, 30mV and 40mV and measure

the respective output voltages.

7. Calculate the voltage gain by using the formula A=Vo/Vin.

OBSERVATION TABLE:

Frequency=1 KHz constant (sine wave)

Vin(pp) Vo Gain=Vo/Vin

30 mV

50 mV

100 mV

2000 mV

WAVEFORMS:

QUESTIONS:

1. What do you understand by Single stage transistor amplifier?

2. Show the various currents and voltages in a single stage transistor amplifier?

3. What do you mean by frequency response of an amplifier?

4. Why there is phase reversal in single stage CE amplifier?

5. Does phase reversal affect amplification?

6. What is the significance of operating point?

7. Why have transistors inherent variations of parameters?

8. How transistors amplify?

CONCLUSION:

Basic Electronics laboratory manual

International Institute of Information Technology, Hinjawadi, Pune.

OBJECTIVE:

1) Identify pins of an op-amp (such as LM741)

2) Implement given voltage equation for 2 inputs with Op

and Difference amplifier(Vo=2 V

THEORY:

The operational amplifier most commonly known as an op

a variety of mathematical operations such as addition, subtraction, multiplication

etc.Op-amp is direct coupled high gain amplifier, usually consisting of one or more

differential amplifiers. An op

package.

The operational amplifier is a versatile device that can be used to amplify DC as well as

AC input signals and was originally designed for computing such mathematical

functions as addition, substation, multiplication, integration. Thus the name op

amplifier stems from its original use for these mathematical operations and is

abbreviated to op-amp with the addition of suitable external feedback components, the

modern day op-amp can be used for a variety of applications such as AC & DC signal

amplification, active filters, oscillators, comparator, regulators, and others.

BLOCK DIAGRAM REPRES

AMPLIFIER:

Since an op-amp is multistage amplifier, it can be represen

Fig.1.

ASSIGNMENT NO. 5

TITLE: STUDY OF OP



amp (such as LM741)

Implement given voltage equation for 2 inputs with Op-amp based summing

and Difference amplifier(Vo=2 V1+3V2 and Vo=4V1-V2)

The operational amplifier most commonly known as an op-amp can be used to perform

atical operations such as addition, subtraction, multiplication

amp is direct coupled high gain amplifier, usually consisting of one or more

differential amplifiers. An op-amp is available as a single integrated circuit (IC)

amplifier is a versatile device that can be used to amplify DC as well as


functions as addition, substation, multiplication, integration. Thus the name op

original use for these mathematical operations and is

amp with the addition of suitable external feedback components, the

amp can be used for a variety of applications such as AC & DC signal

filters, oscillators, comparator, regulators, and others.

BLOCK DIAGRAM REPRESENTATION OF A TYPICAL OPERATIONAL

amp is multistage amplifier, it can be represented as block diagram as show

ASSIGNMENT NO. 5

STUDY OF OP-AMP BASED AMPLIFIER CIRCUITS

Dept of Applied sciences and Engineering

Page 44

amp based summing

amp can be used to perform

atical operations such as addition, subtraction, multiplication

amp is direct coupled high gain amplifier, usually consisting of one or more

amp is available as a single integrated circuit (IC)

amplifier is a versatile device that can be used to amplify DC as well as


functions as addition, substation, multiplication, integration. Thus the name operational

original use for these mathematical operations and is

amp with the addition of suitable external feedback components, the

amp can be used for a variety of applications such as AC & DC signal

filters, oscillators, comparator, regulators, and others.

L OPERATIONAL

ted as block diagram as show

R CIRCUITS



Fig.5.1: Block diagram of a typical op-amp

The input stage is dual input balanced output differential amplifier. This stage generally

provides most of the voltage gain of the amplifier and also establishes the input

resistance of op-amp. The intermediate stage is usually another differential amplifier,

which is driven by the output of first stage. In most amplifiers the intermediate stage is

dual input unbalanced output. Because the direct coupling is used, the dc voltage at the

output of intermediate stage is well above ground potential. Therefore, generally the

level translator (shifting) circuit is used after the intermediate stage to shift the dc level

at the output of intermediate stage downward to zero volts with respect to ground. The

final is usually a push-pull complementary amplifier output stage. The output stage

increases the output voltage swing and raises the current supplying capability of the

op-amp. A well-designed output stage also provides low output resistance.The op-amp

is available in an IC as shown. It is an 8 pin IC with the following terminals.

Fig. 5.2: IC 741 op-amp

V- (pin 2) and V+ (pin 3) are the inverting and non-inverting inputs, respectively. Vout

(pin 6) is the output. +Vcc (pin 7) and –Vcc (pin 4) are the two power supply voltages

needed to power the op-amp. For the 741, +Vcc is +15 V and –Vcc is -15 V. The two

supply voltages limit the output voltage range (from +Vcc to –Vcc). If the gain would

yield an output voltage above +Vcc or below -Vcc, then the output “saturates” at +Vcc

or -Vcc, respectively.

The opamp can be used as an adder or a summing amplifier and a subtractor or a

difference amplifier as shown below.



Fig.5.3: summing amplifier Fig.5.4: difference amplifier

As the input impedence of an op-amp is extremely large, more than one input signal

can be applied to the inverting amplifier. Such circuit gives the addition of the applied

signals at the output. Hence it is called as a summing amplifier or an adder circuit.

Depending upon the sign of the output, the adders are classified as inverting or non-

inverting summing amplifier. Fig. 3 shows an inverting summing amplifier where all

the signals to be added are applied to the inverting input terminal of the opamp. The

circuit shows an adder with two inputs and a negative feedback is used. The output of

the circuit is:

If the resistances are equal i.e. R1=R2= then

Vo = -(V1+V2)

Thus the magnitude of the output voltage is the sum of the input voltages and hence the

circuit is called as an adder. We have to design an adder for the equation:

Vo=2V1+3V2.

Referring above equation , we can say that:

2 and

3

Therefore if RF=10KΩ then R1=5KΩ and R2=3.3KΩ

Fig. 4 shows a difference amplifier which performs subtraction of the two input

voltages. The output voltage is given by:

( )

If Rf = R1 then

Vo=V2-V1



By selecting proper values of R1, R2 and Rf we can have the subtraction of two inputs

with appropriate strengths like: Vo=aV2-bV1.

APPARATUS: Circuit board, Signal generator, CRO, CRO probes, connecting wires,

connecting wires, Dual DC power supply etc

PROCEDURE:



3. Make the connection as per the circuit diagram for summing amplifier.

4. Apply the inputs and measure the output voltage.

5. Make the connection as per the circuit diagram for difference amplifier.

6. Apply the inputs and measure the output voltage.

OBSERVATION TABLES:

1. Adder: 2. Subtractor:

QUESTIONS:

1. What is an Operational Amplifier?

2. What is a Differential Amplifier?

3. What do you mean by inverting and non-inverting input of a differential

Amplifier?

4. What do you mean by slew rate of an OPamp?

5. Discuss two applications of Summing amplifier?

6. What is the need of negative feedback in an OPamp?

7. What is a voltage follower?

8. What do you mean by Open loop voltage gain and closed loop voltage gain of an

OPamp?

CONCLUSION:

Sr. No

Input voltage Output

voltage

V1 V2

1

2

3

Sr. No Input voltage

Output

voltage

V1 V2

1

2

3



OBJECTIVE:

1. Identify pins of IC 555 Timer

2. Observe output Observe output waveform and measure frequency of output

wave for IC 555 timer used in Astable mode

THEORY: The 555 timer is an extremely versatile integrated circuit which can be used

to build lots of different circuits. This IC is a monolithic timing circuit that can produce

accurate and highly stable time delays or oscillation. Like other commonly used op-

amps, this IC is also very much reliable, easy to use and cheaper in cost. It has a variety

of applications including monostable and astable multivibrators, digital logic probes,

waveform generators, analog frequency meters and tachometers, and control devices,

voltage regulators etc. The timer basically operates in one of the two modes either as a

monostable (one-shot) multivibrator or as an astable (free-running) multivibrator. The

pin diagram of IC 555 is as follows:

Fig. 6.1: IC 555 pin diagram

Pin 1: Grounded Terminal: All the voltages are measured with respect to this terminal.

Pin 2: Trigger Terminal: This pin is an inverting input to a comparator that is

responsible for transition of flip-flop from set to reset. The output of the timer depends

on the amplitude of the external trigger pulse applied to this pin.

Pin 3: Output Terminal: Output of the timer is available at this pin. There are two ways

in which a load can be connected to the output terminal either between pin 3 and

ASSIGNMENT NO. 6

TITLE: STUDY OF IC 555 TIMER CIRCUIT



ground pin (pin 1) or between pin 3 and supply pin (pin 8). The load connected

between pin 3 and ground supply pin is called the normally on load and that connected

between pin 3 and ground pin is called the normally off load.

Pin 4: Reset Terminal: To disable or reset the timer a negative pulse is applied to this

pin due to which it is referred to as reset terminal. When this pin is not to be used for

reset purpose, it should be connected to + VCC to avoid any possibility of false

triggering.

Pin 5: Control Voltage Terminal: The function of this terminal is to control the

threshold and trigger levels. Thus either the external voltage or a pot connected to this

pin determines the pulse width of the output waveform. The external voltage applied to

this pin can also be used to modulate the output waveform. When this pin is not used, it

should be connected to ground through a 0.01 micro Farad to avoid any noise problem.

Pin 6: Threshold Terminal: This is the non-inverting input terminal of comparator 1,

which compares the voltage applied to the terminal with a reference voltage of 2/3 VCC.

The amplitude of voltage applied to this terminal is responsible for the set state of flip-

flop.

Pin 7: Discharge Terminal: This pin is connected internally to the collector of transistor

and mostly a capacitor is connected between this terminal and ground. It is called

discharge terminal because when transistor saturates, capacitor discharges through the

transistor. When the transistor is cut-off, the capacitor charges at a rate determined by

the external resistor and capacitor.

Pin 8: Supply Terminal: A supply voltage of + 5 V to + 18 V is applied to this terminal

with respect to ground (pin 1).

ASTABLE MULTIVIBRATOR:

Astable multivibrator has one stable state and one quasi stable state. The circuit is

useful for generating single output pulse of time duration in response to a triggering

signal.The width of output pulse depends on external components connected to the op-

amp.

DESIGN EQUATIONS:

Charging time (output high): 0.693*(R1+R2)*C



Discharging time (output low): 0.693*R2*C

Total time period: 0.693*(R1+2*R2)

CIRCUIT DIAGRAM:

Fig. 6.2: Circuit diagram of Astable Multivibrator

APPARATUS: Bread board, CRO, CRO probes, connecting wires, power supply

PROCEDURE:



3. Make the connection as per the circuit diagram for astable multivibrator.

4. Apply +5V supply and observe the output signal.

5. Measure TON and TOFF of the output waveform and theoretical values are verified

with practical values.

6. Calculate duty cycle and frequency.

OBSERVATION TABLE:

TON =

0.69(R1+R2)C

TOFF =

(0.069R2C)

T =

(TON+TOFF)

Frequency % Duty cycle

Calculated Observed

(1/T) Calculated

Observed

(TON/(TON+TOFF))



CALCULATIONS:

For the given circuit:

R1 = ------, R2 = -------, C = ---------;

F = .

-------------------------------theoretical frequency

% Duty cycle =

OUTPUT WAVEFORMS:

QUESTIONS:

1. What is a Multivibrator?

2. What are the different types of multivibrator?

3. What are the basic components of an oscillator circuit?

4. Name the five basic elements in a 555 timer IC.

5. When the 555 timer is configured as an astable multivibrator, hoe is the duty

cycle determined?

6. What are the two comparator reference voltages In a 555 timer when Vcc=10V.

7. How to set duty cycle more than 50% and less than 50%.

8. To what value must c can be changed in ckt given to acheve a frequency of

25kHz?

CONCLUSION:



OBJECTIVE: Study of digital circuits

1. Identify pins of Digital logic gate ICs such as AND, OR, NOT, EX-OR, NAND

2. Implement Half Adder and full Adder circuit with basic logic gate ICs

THEORY:

The electronics system or circuit in which the voltage levels assume a finite number of

discrete values is called as a digital system. The digital circuits are called logic circuits

as they process and represent logic voltage levels. The digital circuit uses binary logic

which consists of only two levels: high level and low level (logic 1 and logic 0). Logic

gate is a logic circuit which obeys a certain set of logic functions. The name logic gate is

derived from the ability of such a device to make decisions in response to different

combinations of the inputs. Various logic gates that are in use are NOT, AND, OR, Ex-

OR, NAND etc. All these logic gates are available in an IC form as shown below:

ASSIGNMENT NO. 7

TITLE: STUDY OF DIGITAL CIRCUITS



Fig. 7.1: Internal pin configuration of a NOT gate, AND gate, OR gate, NAND

gate and EX-OR gate

Truth Table of Basic logic gates is as shown below:

Logic circuit that performs binary addition is called electronic adder or adder. It

consists of properly added logic gates.

There are two types of adders

1. Half Adder 2.Full Adder

Basic Electronics laboratory manual


1. Half Adder:

The logic circuit that can add two binary bits (0 or 1) is called half adder.

block symbol of the half adder. The adder circuit would need two inputs and two

outputs. The two inputs are for two digits to be added either 0 or 1. One output

terminal is for the sum of the two inputs and other output is for the carry.

the addition table of the adder and called truth table.

The half adder would behave according to truth table

Fig. 7.2: Half Adder

Observing the truth table we can see that the output column (sum and carry) can be

produced by using two gates.

I) Sum column is the output of XOR gate

II) Carry column is output of AND gate.

Thus we can produce half adder us

shown in Fig. below.

Logic diagram:

Fig.7.

2. Full Adder:

A full adder adds two binary bits plus carry input (Cin) to produce th

(Co) outputs. Fig. 3 shows block diagram of full adder.



The logic circuit that can add two binary bits (0 or 1) is called half adder.



inal is for the sum of the two inputs and other output is for the carry.

the addition table of the adder and called truth table.

The half adder would behave according to truth table.


produced by using two gates.

Sum column is the output of XOR gate

Carry column is output of AND gate.

Thus we can produce half adder using two input AND gate and two input XOR gate as

7.3: Logic Diagram of Half Adder

A full adder adds two binary bits plus carry input (Cin) to produce the Sum and Carry

3 shows block diagram of full adder.

Inputs Outputs

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

Dept of Applied sciences and Engineering

Page 54

The logic circuit that can add two binary bits (0 or 1) is called half adder. Fig. 1 shows



inal is for the sum of the two inputs and other output is for the carry. Fig. 7.2 shows


ing two input AND gate and two input XOR gate as

e Sum and Carry

Outputs

Carry

0

0

0

1



Fig. 7.4: Full Adder

It is formed by using two half adder circuit and an OR gate as shown in Fig. below.

Logic diagram:

Fig. 7.5: Logic Diagram of Full Adder

APPARATUS: Digital Trainer kit, connecting wires, basic gate ICs.

PROCEDURE:

1. Build the circuit as above on bread board.

2. Make the connections and apply the supply voltage.

3. See the result as per truth table

Inputs Outputs A B Cin Sum Carry 0 0 0 0 0 0 1 0 1 0 1 0 0 1 0 1 1 0 0 1 0 0 1 1 0 0 1 1 0 1 1 0 1 0 1 1 1 1 1 1



OBSERVATION TABLE:

Half Adder: Full Adder:

Inputs Outputs

A B Sum Carry

0 0

0 1

1 0

1 1

QUESTIONS:

1. What are the logic Gates?

2. What are the logic circuits, Logic function and logical variables?

3. Design a full adder using half adder.

4. Implement half adder and full adder using NAND gates only.

5. What are the universal gates? Why these are called so?

6. What is the drawback of half adder?

7. Design EX-OR gate using NAND gates only.

8. How to use Ex-OR Gate and EX-NOR gate as Inverter?

CONCLUSION:

Inputs Outputs

A B Cin Sum Carry

0 0 0

0 1 0

1 0 0

1 1 0

0 0 1

0 1 1

1 0 1

1 1 1



OBJECTIVE: Build and test any circuit using IC such as Op-amp LM 741, IC 555 timer,

LM 78XX, LM 79XX or any digital logic gate IC.

APPARATUS: Digital trainer kit, connecting wires, bread board, respective IC’s.

THEORY:

OBSERVATION TABLE:

ASSIGNMENT NO. 8

TITLE: BUILD AND TEST SIMPLE APPLICATION CIRCUIT



CONCLUSION:

Documents

ASSIGNMENT NO · in accordance with Ohm's law: V = IR . The resistance R is equals to the voltage drop V across the resistor divided by the current I through the resistor. The primary