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Page 1: INTRODUCTION

Design of a Clap Activated Switch

ANNAMACHARYA INSTITUTE OF TECHNOLOGY AND

SCIENCES,

TIRUPATI.DEPARTMENT OF ELECTRICAL &ELECTRONIC

ENGINEERING

MINI PROJECT ON: DESIGN OF CLAP ACTIVATED SWITCH

PROJECT GUIDE : Mr. Jakeer Hussain, B.TECH, M.E

ASSOCIATE PROFESSOR, Department Of E.E.E, A.I.T.S,TIRUPATHI.

PROJECT MEMBERS:

1) K.SENTHIL KUMAR : 07AK1A02452) R.NARENDRA : 07AK1A02283) Y.SANDEEP KUMAR : 07AK1A0242

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Design of a Clap Activated Switch

ABSTRACT

This circuit can switch on and off a light, a fan, a

radio or a T.V. etc., by a sound of a clap.

The sound of clap is received by a small micro-phone

(condenser) that is shown by resistor r1 in the circuit. The signal

is further amplified by transistors Q1, Q2, Q3. The relay contact is

connected to the power line and hence turns on/off any electrical

device at output socket.

The components included are resistors 15k, 2M,

270K, 3K , 27K, 1K,10K,2K,Capacitors 0.01 µF, 0.047 µF,

1000µF/16V. Transistors Q1234-BC 149, Diodes IN 4002, IN 4148.

Transformer of 12v/300mA, condenser mic, 12v single charge

over relay.

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Design of a Clap Activated Switch

Design of a Clap Activated Switch

INTRODUCTION

1.1. INTRODUCTION

This circuit can switch on and off a light, a fan or a radio etc; by the

sound of a clap.

This circuit is constructed using basic electronic components like

resistors, transistors, relay, transformer, capacitors. This circuit turns ‘ON’

light for the first clap. The light turns ON till the next clap. For the next clap

the light turns OFF. This circuit works with 12V voltage .Therefore a step-

down transformer 12V/300mA is employed.

The working of this circuit is based on amplifying nature of the

transistor, switching nature of transistor, and relay as an electronic switch.

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Design of a Clap Activated Switch

2.1 COMPONENTS USED:

RESISTOR

CAPACITOR

SEMICONDUCTORS

TRANSISTORS

DIODE

TRANSFORMER 12V/300mA

CONDENSER MIC

RELAY 12V single charge over relay

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Design of a Clap Activated Switch

2.2 COMPONENTS DESCRIPTION

2.2.1 INTRODUCTION OF RESISTOR:

A resistor is a two-terminal electrical or electronic

component that resists an electric current by producing a voltage drop

between its terminals in accordance with Ohm's law: R=V/I The electrical

resistance is equal to the voltage drop across the resistor divided by the

current through the resistor. Resistors are used as part of electrical networks

and electronic circuits.

Resistors are elements of electrical networks and

electronic circuits and are ubiquitous in most electronic equipment. Practical

resistors can be made of various compounds and films, as well as resistance

wire (wire made of a high- resistivity alloy, such as nickel/chrome).

The primary characteristics of a resistor are the

resistance, the tolerance, maximum working voltage and the power rating.

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Design of a Clap Activated Switch

Other characteristics include temperature coefficient, noise, and inductance.

Less well-known is critical resistance, the value below which power

dissipation limits the maximum permitted current flow, and above which the

limit is applied voltage. Critical resistance is determined by the design,

materials and dimensions of the resistor.

Resistors can be integrated into hybrid and printed circuits,

as well as integrated circuits. Size, and position of leads (or terminals) are

relevant to equipment designers; resistors must be physically large enough

not to overheat when dissipating their power.

2.3 RESISTORS USED:-

R1 15K

R2,5,12 2.2M

R3 270K

R4 3.3K

R6,10 27K

R7,11 1.5K

R8,9 10K6

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Design of a Clap Activated Switch

R13 2.2K

3.1 INTRODUCTION TO CAPACITOR:-

An electric circuit element used to store charge temporarily,

consisting in general of two metallic plates separated and insulated from

each other by a dielectric. Also called condenser.

A capacitor (formerly known as condenser) is a passive electronic

capacitor consisting of a pair of conductors separated by a dielectric

(insulator). When a potential difference (voltage) exists across the

conductors, an electric field is present in the dielectric. This field stores

energy and produces a mechanical force between the conductors. The effect

is greatest when there is a narrow separation between large areas of

conductor, hence capacitor conductors are often called plates.

An ideal capacitor is

characterized by a single constant value, capacitance, which is measured in 7

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Design of a Clap Activated Switch

farads. This is the ratio of the electric charge on each conductor to the

potential difference between them. In practice, the dielectric between the

plates passes a small amount of leakage current. The conductors and leads

introduce an equivalent series resistance and the dielectric has an electric

field strength limit resulting in a breakdown voltage.

Capacitors are

widely used in electronic circuits to block direct current while allowing

alternating current to pass, to filter out interference, to smooth the output of

power supplies , and for many other purposes. They are used in resonant

circuits in radio frequency equipment to select particular frequencies from a

signal with many frequencies.

3.2 CAPACITORS USED:

C1 0.01UF

C2,3 0.047UF

C4 1000UF/16V

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3.2.2 CAPACITORS

4.1 INTRODUCTION TO SEMICONDUCTORS:-

semiconductor is a material that has an electrical

conductivity between that of a conductor and an insulator. This means

roughly in the range 103 Siemens per centimeter to 10−8 S/cm. Devices made

from semiconductor materials are the foundation of modern electronics,

including radio, computers, telephones, and many other devices.

Semiconductor devices include the various types of transistor, solar cells,

many kinds of diodes including the light-emitting diode, the silicon controlled

rectifier, and digital and analog integrated circuits. Similarly, semiconductor

solar photovoltaic panels directly convert light energy into electrical energy.

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In a metallic conductor, current is carried by the flow of electrons. In

semiconductors, current can be carried either by the flow of electrons or by

the flow of positively charged "holes" in the electron structure of the

material.

Common semiconducting materials are crystalline solids but

amorphous and liquid semiconductors are known. These include mixtures of

arsenic, selenium and tellurium in a variety of proportions. Such compounds

share with better known semiconductors intermediate conductivity and a

rapid variation of conductivity with temperature, as well as occasional

negative resistance. However, such disordered materials lack the rigid

crystalline structure of conventional semiconductors such as silicon and so

are relatively insensitive to impurities and radiation damage. Organic

semiconductors, that is, organic materials with properties resembling

conventional semiconductors are also known.

Silicon is used to create most semiconductors commercially.

Dozens of other materials are used, including germanium, gallium arsenide,

and silicon carbide. A pure semiconductor is often called an “intrinsic”

semiconductor. The conductivity, or ability to conduct, of common

semiconductor materials can be drastically changed by adding other

elements, called “impurities” to the melted intrinsic material and then

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Design of a Clap Activated Switch

allowing the melt to solidify into a new and different crystal. This process is

called "doping.

4.1.1 SEMICONDUCTOR CHIPS

4.2 SEMI CONDUCTORS USED:

TRANSISTORS AND DIODES

5.1 INTRODUCTION OF DIODE:

1. An electronic device that restricts current flow chiefly to one direction .

2. An electron tube having a cathode and an anode .

3. A two-terminal semiconductor device used chiefly as a rectifier .

In electronics, a diode is a two-terminal electronic component

that conducts electric current in only one direction. The term usually refers

to a semiconductor diode, the most common type today. This is a 11

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Design of a Clap Activated Switch

crystalline piece of semiconductor material connected to two electrical

terminals. A vacuum tube diode (now little used except in some high-

power technologies) is a vacuum tube with two electrodes; a plate and a

cathode.

The most common function of a diode is to allow an

electric current to pass in one direction (called the diode's forward direction)

while blocking current in the opposite direction (the reverse direction). Thus,

the diode can be thought of as an electronic version of a check valve. This

unidirectional behavior is called rectification, and is used to convert

alternating current to direct current, and to extract modulation from radio

signals in radio receivers.

However, diodes can have more complicated behavior than this

simple on-off action, due to their complex non-linear electrical

characteristics, which can be tailored by varying the construction of their P-N

junction. These are exploited in special purpose diodes that perform many

different functions. For example, specialized diodes are used to regulate

voltage (Zener diodes), to electronically tune radio and TV receivers

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(varactor diodes), to generate radio frequency oscillations (tunnel diodes),

and to produce light (light emitting diodes).

Diodes were the first semiconductor electronic devices. The

discovery of crystals' rectifying abilities was made by German physicist

Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker

diodes were made of crystals of minerals such as galena. Today most diodes

are made of silicon, but other semiconductors such as germanium are

sometimes

5.1.1.DIODE

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DIODES USED:

D1 IN 4002

D2,3,4,5 IN 4148

6.1 TRANSISTOR:

INTROCUTION OF TRANSISTORS :

A 'transistor' is a semiconductor device,

commonly used as an amplifier or an electrically controlled

switch. The transistor is the fundamental building block of the

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circuitry in computers, cellular phones, and all other modern

electronic devices.

Because of its fast response and accuracy, the transistor is used in a wide variety of digital and analog functions, including amplification, switching, voltage regulation, signal modulation, and oscillators. Transistors may be packaged individually or as part of an integrated circuit, some with over a billion transistors in a very small area. TRANSISTORS USED:

Q1,2,3,4 BC 149

7.1 TRANSFORMER:

INTRODCTION OF TRANSFORMER

A device used to transfer electric energy from one

circuit to another, especially a pair of multiply wound, inductively coupled

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wire coils that effect such a transfer with a change in voltage, current, phase,

or other electric characteristic.

A transformer is a device that transfers electrical energy

from one circuit to another through inductively coupled conductors—the

transformer's coils. A varying current in the first or primary winding creates a

varying magnetic flux in the transformer's core, and thus a varying magnetic

field through the secondary winding. This varying magnetic field induces a

varying electromotive force (EMF) or "voltage" in the secondary winding. This

effect is called mutual induction.

If a load is connected to the secondary, an electric current

will flow in the secondary winding and electrical energy will be transferred

from the primary circuit through the transformer to the load. In an ideal

transformer, the induced voltage in the secondary winding (VS) is in

proportion to the primary voltage (VP), and is given by the ratio of the

number of turns in the secondary (NS) to the number of turns in the primary

(NP) as follows:

By appropriate selection of the ratio of turns, a transformer thus allows

an alternating current (AC) voltage to be "stepped up" by making NS greater

than NP, or "stepped down" by making NS less than NP.16

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In the vast majority of transformers, the windings are coils wound

around a ferromagnetic core, air-core transformers being a notable

exception.

Transformers range in size from a thumbnail-sized

coupling transformer hidden inside a stage microphone to huge units

weighing hundreds of tons used to interconnect portions of power grids. All

operate with the same basic principles, although the range of designs is

wide. While new technologies have eliminated the need for transformers in

some electronic circuits, transformers are still found in nearly all electronic

devices designed for household ("mains") voltage. Transformers are

essential for high voltage power transmission, which makes long distance

transmission economically practical.

Step down transformers are designed to reduce electrical voltage. Their primary voltage is greater than their secondary voltage. This kind of transformer "steps down" the voltage applied to it. For instance, a step down transformer is needed to use a 110v product in a country with a 220v supply.

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Step down transformers convert electrical voltage from one level

or phase configuration usually down to a lower level. They can include

features for electrical isolation, power distribution, and control and

instrumentation applications. Step down transformers typically rely on the

principle of magnetic induction between coils to convert voltage and/or

current levels.

Step down transformers are made from two or more coils of

insulated wire wound around a core made of iron. When voltage is applied to

one coil (frequently called the primary or input) it magnetizes the iron core,

which induces a voltage in the other coil, (frequently called the secondary or

output). The turns ratio of the two sets of windings determines the amount of

voltage transformation.

An example of this would be: 100 turns on the primary and 50 turns on the

secondary, a ratio of 2 to 1.

Step down transformers can be considered nothing more than a voltage ratio

device.

With step down transformers the voltage ratio between primary and

secondary will mirror the "turns ratio" (except for single phase smaller than 1

kva which have compensated secondaries). A practical application of this 2

to 1 turns ratio would be a 480 to 240 voltage step down. Note that if the

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input were 440 volts then the output would be 220 volts. The ratio between

input and output voltage will stay constant. Transformers should not be

operated at voltages higher than the nameplate rating, but may be operated

at lower voltages than rated. Because of this it is possible to do some non-

standard applications using standard transformers.

Single phase step down transformers 1 kva and larger may also be reverse

connected to step-down or step-up voltages. (Note: single phase step up or

step down transformers sized less than 1 KVA should not be reverse

connected because the secondary windings have additional turns to

overcome a voltage drop when the load is applied. If reverse connected, the

output voltage will be less than desired.)

8.1 RELAY:

INTRODCTION OF RELAYS

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A relay is an electrical switch that opens and closes under

the control of another electrical circuit. In the original form, the switch is

operated by an electromagnet to open or close one or many sets of contacts.

It was invented by Joseph Henry in 1835. Because a relay is able to control

an output circuit of higher power than the input circuit, it can be considered,

in a broad sense, to be a form of an electrical amplifier.

8.2 RELAY OPERATION :

All relays operate using the same basic principle. Our example will use a commonly used 4 - pin relay. Relays have two circuits: A control circuit (shown in GREEN) and a load circuit (shown in RED). The control circuit has a small control coil while the load circuit has a switch. The coil controls the operation of the switch.

8.3 RELAY ENERGIZED (ON) :

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Current flowing through the control circuit coil (pins 1 and 3) creates a small magnetic field which causes the switch to close, pins 2 and 4. The switch, which is part of the load circuit, is used to control an electrical circuit that may connect to it. Current now flows through pins 2 and 4 shown in RED, when the relay is energized.

8.4 RELAY DE-ENERGIZED (OFF) : When current

stops flowing through the control circuit, pins 1 and 3, the relay becomes de-

energized. Without the magnetic field, the switch opens and current is

prevented from flowing through pins 2 and 4. The relay is now OFF

.

9.1 CONDENSER MIC:

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INTRODUCTION OF CONDENSER MICROPHONE

Condenser means capacitor, an

electrCondenonic component which stores energy in the form of

an electrostatic field. The term condenser is actually obsolete but

has stuck as the name for this type of microphone, which uses a

capacitor to convert acoustical energy into electrical energy.

Condenser microphones require power from a

battery or external source. The resulting audio signal is stronger

signal than that from a dynamic. Condensers also tend to be more

sensitive and responsive than dynamics, making them well-suited

to capturing subtle nuances in a sound. They are not ideal for

high-volume work, as their sensitivity makes them prone to

distort.

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4.9.1 CONDENSER MICROPHONE

9.2 Mic Level and Line Level :

The current generated by a microphone is very

small and this current is referred

to as mic level and typically measured in milli-volts. Before it is

usable, the signal must be amplified, usually to line level, with

typical value within (0.5 – 2) volts, which is stronger and more

robust signal. The line level is the standard signal strength used

by audio processing equipment

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10 CIRCUIT DIAGRAM

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11.1 OPERATION:

Here is a circuit that can switch on & off a light, Fan, Radio etc.

by the sound of clap .The sound of clap is received by a small microphone

that is shown biased by resistor R1 in the circuit. The microphone changes

sound wave in to electrical wave which is further amplified by Q1. Transistor

Q1 is used as common emitter circuit to amplify weak signals received by

the microphone. Amplified output from the collector of transistor Q1 is then

feed to the Bistable Multivibrator circuit also known as flip-flop.

Flip flop circuit is made by using 2 Transistor, in our circuit Q2&Q3. In a flip-flop circuit, at a time only one transistor conduct and other cut off and when it gets a trigger pulse from outside source then first transistor is cutoff and 2nd transistor conducts.

Thus output of transistor is either logic-0 or logic-1

and it remains in one state 0 or 1 until it gets trigger pulse from

outer source.

The pulse of clap which is trigger for flip-flop makes

changes to the output which is complementary (reverse). Decision of flip-flop

which is in the low current form is unable to drive relay directly so we have

used a current amplifier circuit by using Q4 which is a common emitter

circuit. Output of Q4 is connected to a Relay (Electromagnetic switch), works

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Design of a Clap Activated Switch

like a mechanical switch. With the help of a relay it is easy for connecting

other electrical appliance.

The relay contact is connected to the power line and hence turns on/off

any electrical appliance connected all the way through relay.

For power supply, we have made 12Volt eliminator with the help of

Transformer T1, Diode D1 and capacitor C1.It is a half wave rectifier.

11.2 AMPLIFIER:

A transistor stage, biased near cut-off (that is, almost no current with no

signal) amplifies the signal from the microphone. The output of the

microphone is coupled to the base of the transistor using an electrolytic

capacitor (note: using a better capacitor here will not work). The top of the

electret microphone is at a few volts, the base conducts at around half a volt,

so the leakage current of the capacitor (all electrolytic capacitors leak at

least a little bit) will eventually cause the steady state condition in which the

leakage of the capacitor goes into the base terminal of the transistor. So the

collector will have Hfe times this leakage, which can usually be ignored.

The first time the microphone output goes positive, however, (because

somebody clapped) this change gets coupled to the base entirely due to the

action of the capacitor. This causes the current through the transistor to

increase, and this increase in current causes the voltage at the collector, 26

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Design of a Clap Activated Switch

which was sitting near the supply voltage, to fall to nearly zero. If you

clapped loudly enough, of course.

This is not a high fidelity audio amplifier. Its function is to produce no output

for small sounds and large output for (slightly) bigger sounds, so the

customary biasing network can be omitted. The 4.7 Megohm resistor in the

previous version was as good as an open circuit, and its omission does not

affect the operation of the clap switch in any way. Provided, of course, that

you use that 10 microfarad electrolytic capacitor.

11.3 Memory:

Two cross connected transistors in a bistable multivibrator arrangement

make up a circuit that remembers. You can set it to one of two possible

states, and it will stay in that state until the end of time. When one transistor

conducts, its collector is near ground, and a resistor from this collector feeds

the base of the other. Since this resistor sees ground at the collector end the

base at the other end receives no current, so that transistor is off. Since this

transistor is off, its collector is near supply potential and a resistor connects

from this to the base of the other transistor. Since this resistor sees voltage,

it supplies the base with current, ensuring that the transistor remains on.

Thus this state is stable. By symmetry, the other state is, too.

11.4 Changing state:

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On a clap, the state of the bistable changes. The output of the amplifier is

converted to a sharp pulse by passing it through a (relatively) low valued

capacitor, of 0.1 microfarads (100 nanofarads). This is connected through

"steering" diodes to the base of the transistor which is conducting. This

transistor stops conducting, and the other transistor was not conducting

anyway. So at a clap, both transistors become off.

Then, those two capacitors across the base resistors come into action. The

capacitor connecting to the base of the transistor which was ON has voltage

across it. The capacitor connecting to the base of the transistor which was

OFF has no voltage across it.

As the sound of the clap dies away, both bases rise towards the supply voltage. But, due to the difference in the charges of the two capacitors, the base of the transistor which was previously not conducting reaches the magic value of half a volt first, and it gets on, and stays on. Until the next clap.

Two red Light Emitting Diodes have been placed in the two collector circuits so that this circuit can be made to work by itself. If you cover up one LED, and display the other prominently, you have it there - a clap operated light.

11.5 Output Stage:

In order to have a decent amount of light from this circuit, I propose to use six white LEDs in three groups of two each. Each series connected string of

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two LEDs is arranged to draw around fifteen milliamperes or so by using a series resistor of 330 ohms. Two LEDs in series will drop about five or six volts, and the remaining battery voltage drop across this resistor determines the current through the LEDs. You can get more brightness from the LEDs by reducing the value to 220 ohms or even 150 ohms, provided you keep within the ratings of the LEDs. Do so at your own risk.

Thus the output stage has to handle around fifty or sixty milliamperes. This will give you fairly long time of claplighting with a PP3 battery. The 100mA filament lamp seems to be somewhat hard to find, and people were using torch bulbs, which run at much higher current, and killing their batteries in a few minutes.

A transistor gets its base driven from the collector of one of the transistors in the bistable. With this connection, due to the base current through it, one red LED in the bistable switches between half bright and full, and the other switches between fully off and on. This is normal.

Because the LEDs do not draw as much current as a filament lamp, the output transistor, too, can be of the common small signal variety. All four could be any small signal n-p-n transistor and the circuit should work. So would it with four p-n-p transistors, provided you switch the polarity of every (polarised) component.

12.0.1Design Calculations

12.1 For transistor Switch :

Using general purpose transistor BC 337

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Supply voltage, Vs = 9V The load driven by the transistor is the relay Rl Load resistance Rl = 150 ohm

Load current I1 = Supply Voltage, Vs Load Resistance, Rl = 9/150 = 60 mA

Since Il (max) must be greater than Il and from the date sheet Ic(max) = 100mA

Ic > Il To calculate for Base Resistor, R2

R2 = Vc×hfe (4.2) 5×Ic

Where Vc = Chip supply voltage

But since Vc = Vs Then

R14 = (Vs×hfe) (4.3) 5×Ic = 9×400

5×100 = 7.2 KΩ

Where the typical hfe value = 400 from the date sheet, and Ic = 100 mA.

Therefore, R14 is selected to be 10 KΩ

12.2 For light Emitting Diode (LED) :

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To determine the value of the voltage dropper resistor, the voltage supply value must be known. From this value, the characteristic voltage drop of an LED can then be subtracted, and the value of drop across an LED depending on the desired brightness and colour will range from 1.2 V to 3.0 V.

If(max) = 20mA Vcc = 9V Vf = 2V

Required current I(req) = 5mA. RLED = Vcc–Vf (4.4) If (max) = 9-2

5×10-3 = 1.4 KΩ (4.5)

But choosing IR (LED) = 10mA R(LED) = 9–2

10×10-3 (4.6) = 0.7 KΩ

Where VF = the maximum forward voltage drop Vcc = the supply voltage RLED = the LED current limiting resistor

Considering equations (4.5) and (4.6)

R9 and R13 are chosen to be 1KΩ

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12.3 Design calculation for condenser microphone: From the data sheet, the electrets condenser microphone has the following specifications:

Rated Voltage = 2V Operating Voltage = 1–10 V Sensitivity = -44+/-3dB S/N = 55dB

The microphone – biasing resistor, R1 is given by

R1 = Vs–V(rated) (4.7) 2mA R1 = 3.5 KΩ

Therefore, R1 was chosen to be 3.3KΩ.

12.4 Design calculation for Transistor Amplifier :An audio low noise transistor is used for the audio signal amplifier circuit in this design, and this is wired in a common-emitter mode. At the saturation level, maximum collector current for an emitter-base design can be determined by applying a short circuit between the collector-emitter terminals. At this point, the voltage across the collector-emitter junction is almost zero.

From data sheet, Vce(sat) = 0.3 V Ic (sat) = Vs-Vce (sat) (4.12) Rc + RE

Where Ic = 2mA 2mA=9–0.3

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Rc+RE Rc +RE=9 – 0.3/ 2×10-3

=4.34KΩ

For linear amplification and maximum output purpose, the operating point

should lie around the dc load-line. The quiescent point normally takes a

value of about half the supply voltage.

The quiescent, Vce = 9/2 (4.13)

= 4.5 V

the emitter terminal is made to be a little above ground level. Therefore,

voltage from emitter to ground, VE is usually arranged to be one tenth of

supply voltage, VS.

VE = VS/10 (4.14)

= 9.0/ 10

= 0.9 V

Hence the emitter resistor

R6 = VE/IE 4.15)

R6 = VE /IE

= VE/ IC

= 0.9/2×10-3

= 450 Ω

The voltage drop across R4 is given by

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Design of a Clap Activated Switch

VB = R4/ R3+R4×VS (4.16)

IB–IBRTH – VBE – IERE=0 (4.17)

Substituting IE = (β + 1) IB into equation 4.17, we have

IB–IBRTH–VBE-(β+1) IBRE=0

IB=VB–VBE/ [RTH+ (β+1) RE] 4.18)

VB = VE–VBE (4.19)

= 0.9 – 0.7

= 0.2 V

From equation 4.16, we have

VB(R1 +R4)=R2VCC (4.20)

0.2 (R1+R4) =9R2

0.2R1 + 0.2R4 = 9R4

R1 = 44R4 (4.21)

And 10R4≤βRE

Where RE=450 Ω and

β = 650 From data sheet R4 ≤650×450 /10 =29,250Ω hence R4 = 30 KΩ then, from equation 4.21, we have R3=44×40 KΩ =1320 KΩ

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=1.3 MΩ VCE = 4.5V from equation 4.13 Then RS + RE = Vs – VCE / IC =9.0 – 4.5 / 2×10-3 RS + RE = 2.25 KΩ RE=2.25 KΩ – 450 Ω

=1.75 KΩ

13.1 :DIFFERENCE BETWEEN CONDENSER MICROPHONE AND DYNAMIC MICROPHONE :

Table1: Comparison Between Dynamic And Condenser

Microphone Dynamic Microphone

Condenser Microphone

Do not have flat frequency response but rather tend to have

tailed frequency response for particular applications

Have a flat frequency

response

Operate with the principle of Electromagnetism as it does

not require voltage supply.

Employs the principle of

electrostatics and

consequently, require

voltage supply across the

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Design of a Clap Activated Switch

capacitor for it to work.

They are suitable for handling high volume level, such as

from certain musical instruments.

They are not ideal for

high volume work as their

sensitivity makes them

prone to distortion.

The signal produced are strong therefore making them

sensitive

The resulting audio signal

is stronger than that from

a dynamic. It also tends to

be more sensitive and

responsive than dynamic.

15.1 APPLICATIONS

This circuit can be used to switch on and off a light, a fan, a radio

or a t.v. by the sound of a clap.

14.2 ADVANTAGES AND DISADVANTAGES OF

CLAPSWITCH:

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Design of a Clap Activated Switch

The major advantage of a clap switch is that you can turn

something (e.g. a lamp) on and off from any location in the room (e.g. while

lying in bed) simply by clapping your hands.

The major disadvantage is that it's generally cumbersome to

have to clap one's hands to turn something on or off and it's generally seen

as simpler for most use cases to use a traditional light switch. The primary

application involves an elderly or mobility-impaired person. A clap switch is

generally used for a light, television, radio, or similar electronic device that

the person will want to turn on/off from bed.

CONCLUSION:

Hereby we would like to conclude that this circuit is very much

useful to switch ON and OFF the household appliances just by clapping

hand .This circuit functions on using the sound energy provided by the clap

which is converted into electrical energy by condenser mic .This circuit turns

on and off a light, a fan, a radio, a t.v. etc using this converted electrical

energy which is used to turn on relay (an electronic switch).

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Page 38: INTRODUCTION

Design of a Clap Activated Switch

References:

1. Edward Hughes, Hughes Electrical technology, Addition Wesley Longman

(Singapore) plc Ltd, India, Seventh Edition, (pp 395-399). (2001)

2. Paul Horonitz and Weinbeild Hill, the Art of Electronics, second Edition,

Cambridge University Ulc.(1995)

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Page 39: INTRODUCTION

Design of a Clap Activated Switch

3. Ray Marston, “Relay Output Circuits”, Electronics Now Magazine, July

1994

4. http://www.kpsec.com : Country circuits, the Electronics club

5. Alex Pounds, “Electronics Tutorial” Denenberg University,

http://www.ffldusoe.edu/faculty/Denenberg/topics/Electronics/

AlexPounds.htmls. Retrieved May 5,2007.

http://www/the 12volt.com.SPDT automobile Relays, 2004

http://www/starmicromics .com/components/mics.html: Microphone series

The Audio Forum “How Microphones Work”, www.mediccollege.com

Tony Van Roon (VA3AVR) “Relays and Relay Drivers” www.starcounter.com

December 6, 2006.

The Electronics Clubs, “Transistor Circuit”, www.kspec.com

www.mccsemi.com. NPN Silicon Amplifier Transistor

39


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