2. › 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.
3. 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
5. 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
6.
7. 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.
8.
9. 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.
10. An electronic device that restricts current
flow chiefly to one direction .
An electron tube having a cathode and an
anode .
A two-terminal semiconductor device
used chiefly as a rectifier .
11.
12. 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.
13. INTRODUCTION 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
circuitry in computers, cellular phones, and
all other modern electronic devices.
14.
15. 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.
16. 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:
17. Vs/Vp = Ns/Np
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.
18. 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.
19. 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.
20. 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.
21.
22. 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.
23.
24. 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
25.
26.
27. 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 fed to the Bistable
Multivibrator circuit also known as flip-flop.
28. 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.
29. 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 like a mechanical switch. With
30. 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.
31. INTRODUCTION OF CONDENSER
MICROPHONE:
Condenser means capacitor, an electronic
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.
32. 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.
35. 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
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
36. 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
37. 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.
38. 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).
39. http://www.kpsec.com: Country circuits, the Electronics club
Alex Pounds, “Electronics Tutorial” Denenberg University,
http://www.ffldusoe.edu/faculty/Denenberg/topics/Electronics/Ale
xPounds.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
