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
2) R.NARENDRA
3) Y.SANDEEP KUMAR
1
:
:
:
07AK1A0245
07AK1A0228
07AK1A0242
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.
2
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
components
circuit
like
is
constructed
resistors,
using
transistors,
basic
relay,
electronic
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.
3
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
4
Design of a Clap Activated Switch
2.2 COMPONENTS DESCRIPTION
2.2.1 INTRODUCTION OF RESISTOR:
A
electrical
or
electronic
resistor
component
is
that
a
resists
two-terminal
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 highresistivity alloy, such as nickel/chrome).
The
resistor
voltage
are
and
the
the
resistance,
power
primary
the
rating.
characteristics
tolerance,
Other
of
a
maximum
working
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.
5
Design of a Clap Activated Switch
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 10K
R13 2.2K
6
Design of a Clap Activated Switch
3.1 INTRODUCTION TO CAPACITOR:An
charge
temporarily,
electric
circuit
consisting
in
element
general
of
used
to
store
two
metallic
plates separated and insulated from each other by a dielectric.
called condenser.
Also
A
capacitor
electronic
separated
(formerly
capacitor
by
a
known
as
consisting
dielectric
condenser)
of
a
(insulator).
pair
When
is
a
of
conductors
a
passive
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 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.
7
Design of a Clap Activated Switch
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
circuits
many
in
other
radio
purposes.
frequency
They
are
equipment
to
used
select
frequencies from a signal with many frequencies.
3.2 CAPACITORS USED:
C1 0.01UF
C2,3 0.047UF
C4 1000UF/16V
3.2.2 CAPACITORS
8
in
resonant
particular
Design of a Clap Activated Switch
4.1 INTRODUCTION TO SEMICONDUCTORS:semiconductor is a material that has
an electrical conductivity between that of a conductor and an
insulator.
This
centimeter
to
means
10−8
roughly
S/cm.
in
the
Devices
range
made
103
from
Siemens
per
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. 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
variation
occasional
of
intermediate
conductivity
negative
with
resistance.
conductivity
and
a
temperature,
as
well
However,
such
rapid
as
disordered
materials lack the rigid crystalline structure of conventional
semiconductors such as silicon and so are relatively insensitive
9
Design of a Clap Activated Switch
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
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
10
Design of a Clap Activated Switch
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
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.
11
Design of a Clap Activated Switch
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
receivers
diodes),
(varactor
oscillations
(tunnel
to
electronically
diodes),
to
diodes),
and
Diodes
were
tune
generate
to
radio
radio
produce
and
TV
frequency
light
(light
emitting diodes).
electronic
devices.
The
discovery
the
of
first
semiconductor
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
12
Design of a Clap Activated Switch
5.1.1.DIODE
DIODES USED:
D1 IN 4002
D2,3,4,5 IN 4148
13
Design of a Clap Activated Switch
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
computers,
building
cellular
block
phones,
of
and
the
all
circuitry
other
in
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
14
Design of a Clap Activated Switch
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 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
coils.
A
creates
a
varying magnetic flux in the transformer's core, and thus
a
varying
coupled
current
in
varying
magnetic
varying
magnetic
conductors—the
the
field
field
first
or
through
induces
transformer's
primary
secondary
the
a
winding
varying
winding.
electromotive
This
force
(EMF) or "voltage" in the secondary winding. This effect is
called mutual induction.
If
secondary,
winding
and
an
electric
electrical
a
current
energy
load
will
will
is
flow
be
connected
in
the
transferred
to
the
secondary
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:
15
Design of a Clap Activated Switch
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.
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
microphone
to
coupling
huge
units
transformer
weighing
hidden
hundreds
inside
of
tons
a
stage
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.
16
Design of a Clap Activated Switch
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.
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,
applications.
Step
down
and
control
transformers
and
instrumentation
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.
17
Design of a Clap Activated Switch
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 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.)
18
Design of a Clap Activated Switch
8.1 RELAY:
INTRODCTION OF RELAYS
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.
19
Design of a Clap Activated Switch
8.3 RELAY ENERGIZED (ON) :
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
.
20
Design of a Clap Activated Switch
9.1 CONDENSER MIC:
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.
21
Design of a Clap Activated Switch
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
audio
22
level
is
the
standard
signal
processing
strength
used
by
equipment
Design of a Clap Activated Switch
10 CIRCUIT DIAGRAM
23
Design of a Clap Activated Switch
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
trigger
for
flip-flop
makes
pulse
changes
to
of
the
clap
which
is
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 like a mechanical switch. With
24
Design of a Clap Activated Switch
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
25
Design of a Clap Activated Switch
current through the transistor to increase, and this increase in
current causes the voltage at the collector, 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
26
Design of a Clap Activated Switch
transistor remains on. Thus this state is stable. By symmetry,
the other state is, too.
11.4 Changing state:
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.
27
Design of a Clap Activated Switch
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 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.
28
Design of a Clap Activated Switch
12.0.1Design Calculations
12.1 For transistor Switch :
Using general purpose transistor BC 337
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
29
Design of a Clap Activated Switch
12.2 For light Emitting Diode (LED) :
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
30
Design of a Clap Activated Switch
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 commonemitter 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
Rc+RE
Rc +RE=9 – 0.3/ 2×10-3
=4.34KΩ
31
Design of a Clap Activated Switch
For
linear
operating
amplification
point
should
and
lie
maximum
around
the
output
dc
purpose,
the
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
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)
32
Design of a Clap Activated Switch
= 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
=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
33
Design of a Clap Activated Switch
13.1 :DIFFERENCE BETWEEN
DYNAMIC MICROPHONE :
CONDENSER
Table1: Comparison Between Dynamic And Condenser
MICROPHONE
Condenser Microphone
Microphone Dynamic Microphone
Do not have flat frequency response but rather tend to have
Have a flat frequency
tailed frequency response for particular applications
response
Operate with the principle of Electromagnetism as it does
Employs the principle of
not require voltage supply.
electrostatics and
consequently, require
voltage supply across the
capacitor for it to work.
They are suitable for handling high volume level, such as
They are not ideal for
from certain musical instruments.
high volume work as their
sensitivity makes them
prone to distortion.
The signal produced are strong therefore making them
The resulting audio signal
sensitive
is stronger than that from
a dynamic. It also tends to
be more sensitive and
responsive than dynamic.
34
AND
Design of a Clap Activated Switch
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:
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
generally
cumbersome
to
major
have
to
disadvantage
clap
one's
is
that
it's
to
turn
hands
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.
35
Design of a Clap Activated Switch
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).
36
Design of a Clap Activated Switch
References:
1. Edward Hughes, Hughes Electrical technology, Addition Wesley
Longman (Singapore) plc Ltd, India, Seventh Edition, (pp 395399). (2001)
2. Paul Horonitz and Weinbeild Hill, the Art of Electronics,
second Edition, Cambridge University Ulc.(1995)
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/Electronic
s/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
37