CHAPTER -1 INTRODUCTION
1.1 INTRODUCTION: This project endeavors that on and off of any electrical appliance by a sound of 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. This working of this circuit is based on amplifying nature of the transistor, switching nature of transistor, and relay as an electronic switch. 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.
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With the help of a relay it is easy for connecting any number of electrical appliances. The relay contact is connected to the power line and hence turns on/off any electrical appliance connected all the way through relay.
1.2 MAIN OBJECTIVE OF CLAP SWITCH: The main objective of clap switch is that on and off of any electrical appliance by a sound of clap. 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. This working of this circuit is based on amplifying nature of the transistor, switching nature of transistor, and relay as an electronic switch.
1.3 STOCK STANDARD CLAP SWITCH: Over the years, the simple clap-switch has been produced for fun projects and novelty gift ideas and today there are many examples to be seen from various suppliers, in many various designs. However, the “stock standard” clap-switch has a number of distinct shortcomings. If for example you have one in your bed room, throw a ball against the wall, or sneeze, and the light goes out! Similarly, a bump in the night can turn the light on. Any number of sharp sounds can switch the clap-switch either on or off. A second shortcoming is that, unless a clap switch is adjusted to respond only to hard, sharp claps, it is likely to be triggered by a variety of unwanted sounds. This also means that “lighter” sounds, such as a clicking of one’s fingers, or tapping a pencil on a desk, are less likely to trigger a “stock standard” clap switch. Instead, far loader, disruptive sounds are required. A third shortcoming is that the standard clap switch offers little security. Anyone who can clap, or even click there fingers or shout, can trigger the switch. While this might not seem at first to hold much of a disadvantage, it significantly limits the possibilities of the switch.
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1.4 MULTI CLAP SWITCH: A sophisticated clap (or tap) switch could circumvent precisely these problems. Tap a code in to your window, and the door lock opens-or knock on your front door in a predetermined sequence, and you. Regain access to your home. All this the Multi-clap switch can do, on a basic level. In brief, the multi-clap switch may be activated with one to nine claps, as preferred. The same number of claps is required to switch it off again. This it does with more then the usual sensitivity. The precise “speed” of the claps may also be set, so that the clapping either too fast or too slowly will reset the switch.
1.5 SWITCHES: In electronics, a switch is an electrical component that 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. A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch. Automatically-operated switches can be used to control the motions of machines, for example, to indicate that a garage door has reached its full open position or that a machine tool is in a position to accept another workpiece. Switches may be operated by process variables such as pressure, temperature, flow, current, voltage, and force, acting as sensors in a process and used to automatically control a system. For example, a thermostat is an automatically-operated switch used to control a heating process. A switch that is operated by another electrical circuit is called a relay. Large switches may be remotely operated by a motor drive mechanism. 3
Some switches are used to isolate electric power from a system, providing a visible point of isolation that can be pad-locked if necessary to prevent accidental operation of a machine during maintenance, or to prevent electric shock.
1.6 SUMMARY: In this chapter a detailed study on introduction of clap switch, major objectives, stock standard, multi clap switch and switches. This project endeavors that on and off of any electrical appliance by a sound of clap.
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CHAPTER 2 HARDWARE IMPLEMENTATION 2.1 INTRODUCTION: In this chapter we will be studying regarding Hardware components which are required in this project. They are regulated power supply, common emitter amplifier etc., Among these the embedded system used here also needs power, in the form of D.C. The available power is A.C. power; hence we need to convert this A.C. power into D.C. power for the operation of the system. 2.1.1 REGULATED POWER SUPPLY: Any electrical system needs power for its operation. The embedded system used here also needs power, in the form of D.C. The available power is A.C. power; hence we need to convert this A.C. power into D.C. power for the operation of the system. The above block diagram describes the various stages involved in the process of conversion of AC power to D.C. 2.1.2 HALF WAVE RECTIFIER: 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. CIRCUIT DIAGRAM:
Fig 2.1.2 Half Wave Rectifier
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The fig shows simple half wave rectifier with output wave forms. In half wave rectification, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output, it is very inefficient if used for power transfer. Half-wave rectification can be achieved with a single diode in a one-phase supply, or with three diodes in a three-phase supply. The circuit shown converts the available domestic 230v A.C voltage to a 5v regulated D.C. supply. The main features of the circuit are discussed below: •
Circuit complexity: Very simple and easy to build
•
Circuit performance: Very stable +5V output voltage, reliable operation
•
Availability of components: Easy to get, uses only very common basic components
•
Applications: Part of electronics devices, small laboratory power supply
•
Power supply voltage: Unregulated DC 8-18V power supply Power supply current: Needed output current + 5 mA.
The Half wave rectifier is a circuit, which converts an ac voltage to dc voltage. In the Half wave rectifier circuit shown above the transformer serves two purposes. 1. It can be used to obtain the desired level of dc voltage (using step up or step down transformers). 2. It provides isolation from the power line. The primary of the transformer is connected to ac supply. This induces an ac voltage across the secondary of the transformer. During the positive half cycle of the input voltage the polarity of the voltage across the secondary forward biases the diode.
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As a result a current I L flows through the load resistor, RL. The forward biased diode offers a very low resistance and hence the voltage drop across it is very small. Thus the voltage appearing across the load is practically the same as the input voltage at every instant. A transformer 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.
2.2 COMMON EMMITER AMPLIFIER: Generally, an amplifier or simply amp is any device that changes, usually increases, the amplitude of a signal. The relationship of the input to the output of an amplifier usually expressed as a function of the input frequency is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain. In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous field-effect transistor circuit is the common-source amplifier. 2.2.1
EMITTER DEGENERATION:
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Fig 2.2.1 EMITTER DEGENERATION
Common-emitter amplifiers can have a very high gain which give the amplified and inverted output and can vary widely from one transistor to the next. The gain is a strong function of both temperature and bias current, and so the actual gain is somewhat unpredictable. Stability is another problem associated with such high gain circuits due to any unintentional positive feedback that may be present. Other problems associated with the circuit are the low input dynamic range imposed by the small-signal limit; there is high distortion if this limit is exceeded and the transistor ceases to behave like its small-signal model. One common way of alleviating these issues is with the use of negative feedback, which is usually implemented with emitter degeneration. Emitter degeneration refers to the addition of a small resistor (or any impedance) between the emitter and the common signal source (e.g., the ground reference or a power supply rail). This impedance RE reduces the overall Tran conductance Gm = gm of the circuit by a factor of gmRE + 1, which makes the voltage gain.
So the voltage gain depends almost exclusively on the ratio of the resistors RC / RE rather than the transistor's intrinsic and unpredictable characteristics. The distortion and stability characteristics of the circuit are thus improved at the expense of a reduction in gain.
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CHARACTERISTICS: At low frequencies and using a simplified hybrid-pi model, the following small-signal characteristics can be derived
Definition
Expression
Current gain Voltage gain Input impedance Output impedance
If the emitter degeneration resistor is not present,
. As expected, when
increased, the input impedance is increased and the voltage gain
is
is reduced
2.2.2 BANDWIDTH: The bandwidth of the common-emitter amplifier tends to be low due to high capacitance resulting from the Miller effect. The parasitic base-collector capacitance appears like a larger parasitic capacitor
(where
ground. 9
is negative) from the base to
This large capacitor greatly decreases the bandwidth of the amplifier as it makes the time constant of the parasitic input RC filter
where
is the output
impedance of the signal source connected to the ideal base. The problem can be mitigated in several ways, including: •
Reduction of the voltage gain magnitude
•
Reduction of the output impedance
(e.g., by using emitter degeneration).
of the signal source connected to the base (e.g., by
using an emitter follower or some other voltage follower). •
Using a cascade configuration, which inserts a low input impedance current buffer (e.g. a common base amplifier) between the transistor's collector and the load. This configuration holds the transistor's collector voltage roughly constant, thus making the base to collector gain zero and hence (ideally) removing the Miller effect.
•
Using a differential amplifier topology like an emitter follower driving a groundedbase amplifier; as long as the emitter follower is truly a common-collector amplifier, the Miller effect is removed. The Miller effect negatively affects the performance of the common-source
amplifier in the same way (and has similar solutions).
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APPLICATIONS: Low frequency voltage amplifier: A typical example of the use of a common-emitter amplifier is shown.
Single-ended NPN common-emitter amplifier with emitter degeneration. The AC-coupled circuit acts as a level-shifter amplifier. Here, the base–emitter voltage drop is assumed to be 0.65 Volts.
Fig 2.2.2 Low frequency voltage amplifier
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The input capacitor C removes any constant component of the input, and the resistors R1 and R2 bias the transistor so that it will remain in active mode for the entire range of the input.
The output is an inverted copy of the AC-component of the input that has been amplified by the ratio RC/RE and shifted by an amount determined by all four resistors. Because RC is often large, the output impedance of this circuit can be prohibitively high. To alleviate this problem, RC is kept as low as possible and the amplifier is followed by a voltage buffer like an emitter follower. 2.2.3 RADIO: Common-emitter amplifiers are also used in radio frequency circuits, for example to amplify faint signals received by an antenna. In this case it is common to replace the load resistor with a tuned circuit. This may be done to limit the bandwidth to a narrow band centered around the intended operating frequency. More importantly it also allows the circuit to operate at higher frequencies as the tuned circuit can be used to resonate any inter-electrode and stray capacitances, which normally limit the frequency response. Common emitters are also commonly used as low-noise amplifiers.
2.3 MULTIVIBRATOR: A Multivibrator is an electronic circuit used to implement a variety of simple two-state systems such as oscillators, timers and flip-flops. It is characterized by two amplifying devices (transistors, electron tubes or other devices) cross-coupled by resistors and capacitors. The most common form is the astable or oscillating type, which generates a square wave the high level of harmonics in its output is what gives the multivibrator its common 12
name. The multivibrator originated as a vacuum tube (valve) circuit described by William Eccles and F.W. Jordan in 1919.
There are three types of multivibrator circuit: •
Astable, in which the circuit is not stable in either state it continuously oscillates from one state to the other.
•
Monostable, in which one of the states is stable, but the other is not the circuit will flip into the unstable state for a determined period, but will eventually return to the stable state. Such a circuit is useful for creating a timing period of fixed duration in response to some external event. This circuit is also known as a one shot. A common application is in eliminating switch bounce.
•
Bistable, in which the circuit will remain in either state indefinitely. The circuit can be flipped from one state to the other by an external event or trigger. Such a circuit is important as the fundamental building block of a register or memory device. This circuit is also known as a flip-flop. In its simplest form the multivibrator circuit consists of two cross-coupled
transistors. Using resistor-capacitor networks within the circuit to define the time periods of the unstable states, the various types may be implemented. Multivibrators find applications in a variety of systems where square waves or timed intervals are required. Simple circuits tend to be inaccurate since many factors affect their timing, so they are rarely used where very high precision is required. Before the advent of low-cost integrated circuits, chains of multivibrators found use as frequency dividers. A free-running multivibrator with a frequency of one-half to one-tenth of the reference frequency would accurately lock to the reference frequency. This technique was used in early electronic organs, to keep notes of different octaves accurately in tune. Other applications included early television systems, where the 13
various line and frame frequencies were kept synchronized by pulses included in the video signal.
2.3.1 BISTABLE MULTIVIBRATOR: Bistable Multivibrators are another type of two state devices similar to the Monostable Multivibrator. Bistable Multivibrators have TWO stable states (hence the name: "Bi"), and they can be switched over from one stable state to the other by the application of a trigger pulse. As Bistable Multivibrators have two stable states they are more commonly known as flip-flop for use in sequential type circuits. Bistable Multivibrators are two state non-regenerative devices and in each state one of the transistors is cut-off while the other transistor is in saturation, this means that the bistable circuit is capable of remaining indefinitely in either stable state. In its simplest form the multivibrator circuit consists of two cross-coupled transistors. Using resistor-capacitor networks within the circuit to define the time periods of the unstable states, the various types may be implemented. Multivibrators find applications in a variety of systems where square waves or timed intervals are required. Simple circuits tend to be inaccurate since many factors affect their timing, so they are rarely used where very high precision is required To change over from one state to the other the circuit requires a suitable trigger pulse and to go through a full cycle, two triggering pulses, one for each stage are required. Its more common name or term of "Flip-flop" relates to the actual operation of the device, as it "Flips" into one logic state, remains there and then changes or "Flops" back into its first original state.
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2.3.2 BISTABLE MULTIVIBRATOR CIRCUIT:
Fig 2.3.2 BISTABLE MULTIVIBRATOR CIRCUIT
The Bistable Multivibrator circuit above is stable in both states, either with one transistor "OFF" and the other "ON" or with the first transistor "ON" and the second "OFF". Switching between the two states is achieved by applying a trigger pulse which inturn will cause the "ON" transistor to turn "OFF". The circuit will switch sequentially by applying a pulse to each base in turn and this is achieved from a single input trigger pulse using biased diodes as a steering circuit. Equally, we could remove the diodes, capacitors and feedback resistors and apply individual trigger pulses directly to the transistor Bases.
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Then unlike Monostable Multivibrators whose output is dependent upon the RC time constant of the feedback components used, the Bistable Multivibrators output is dependent upon the application of two individual trigger pulses. So Monostable Multivibrators can produce a very short output pulse or a much longer rectangular shaped output whose leading edge rises in time with the externally applied trigger pulse and whose trailing edge is dependent upon a second trigger pulse as shown below. BISTABLE MULTIVIBRATOR WAVEFORMS:
Fig 2.3.3 BISTABLE MULTIVIBRATOR WAVEFORMS
DETAILED DESCRIPTION OF BISTABLE:
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Fig 2.3.4 DETAILED DESCRIPTION OF BISTABLE
When power is first applied, the voltage divider networks place a negative voltage at the bases of Q1 and Q2. Both transistors have forward bias and both conducts due to some slight difference between the two circuits, one transistor will conduct more than the other. Assume that Q1 conducts more than Q2. The increased conduction of Q1 causes the collector voltage of Q1 to be less negative (more voltage drop across R1). This decreases the forward bias of Q2 and decreases the conduction of Q2. When Q2 conducts less, its collector voltage becomes more negative. The negative-going change at the collector of Q2 is coupled to the base of Q1 and causes Q1 to conduct even more heavily. This regenerative action continues until Q2 is cut off and Q1 is saturated. The circuit is in a stable state and will remain there until a trigger is applied to change the state. At T1, a negative trigger is applied to both bases through C1 and C2. The trigger does not affect Q1 since it is already conducting. The trigger overcomes cutoff bias on Q2 and causes it to conduct. As Q2 goes into conduction, its collector voltage becomes positive. The positive-going change at the Q2 collector causes a reverse bias on the base of Q1. As the conduction of Q1 decreases to the cutoff point, the collector voltage becomes negative. This switching action causes a very rapid change of state with Q2 now conducting and Q1 cut off. At T2, a negative trigger is again applied to both bases. This time, Q1 is brought into conduction and the regenerative switching action cuts off Q2. The bistable multivibrator will continue to change states as long as triggers are applied. Notice that two input triggers are required to produce one gate; one to turn it on and the other to turn it off. The input trigger frequency is twice the output frequency. 17
WAVE FORMS:
Fig 2.3.5 DETAILED DESCRIPTION OF BISTABLE WAVE FORMS
APPLICATIONS OF BISTABLE MULTIVIBRATOR: 1. It is used for the performance of many digital operations such as counting and storing binary information. 2. It is also used in the generation and processing of pulse-type waveforms. 3. As frequency dividers because the output pulses have a frequency that are exactly one half (f/2) that of the trigger input pulse frequency 4. Also used for relay-control functions and for a variety of similar applications in radar and communications systems.
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2.4 SUMMARY: In this chapter a detailed study on hardware implementation of clap switch. They are regulated power supply, common emitter amplifier etc., Among these the embedded system used here also needs power, in the form of D.C. The available power is A.C. power; hence we need to convert this A.C. power into D.C. power for the operation of the system.
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Chapter 3 INCANDESCENT LAMP 3.1 INTRODUCTION: The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence (a general term for heat-driven light emissions which includes the simple case of black body radiation). An electric current passes through a thin filament, heating it until it produces light. The enclosing glass bulb prevents the oxygen in air from reaching the hot filament, which otherwise would be destroyed rapidly by oxidation. Incandescent bulbs are also sometimes called electric lamps, a term also applied to the original arc lamps. Incandescent bulbs are made in a wide range of sizes and voltages, from 1.5 volts to about 300 volts. They require no external regulating equipment and have a low manufacturing cost, and work well on either alternating current or direct current. As a result the incandescent lamp is widely used in household and commercial lighting, for portable lighting, such as table lamps, some car headlamps and electric flashlights, and for decorative and advertising lighting. Some applications of the incandescent bulb make use of the heat generated, such as incubators, brooding boxes for poultry, heat lights for reptile tanks, infrared heating for industrial heating and drying processes, and the Easy-Bake Oven toy. In cold weather the heat shed by incandescent lamps contributes to building heating, but in hot climates lamp losses increase the energy used by air conditioning systems. Incandescent light bulbs are gradually being replaced in many applications by other types of electric light such as (compact) fluorescent lamps, high-intensity discharge lamps, light-emitting diodes (LEDs), and other devices. 20
These newer technologies give more visible light for the same amount of electrical energy input, and often generate much less heat. Some jurisdictions, such as the European Union are in the process of phasing-out the use of incandescent light bulbs in favor of more energy-efficient lighting.
3.2 CONSTRUCTION OF INCANDESCENT LAMP: Incandescent light bulbs consist of a glass enclosure (the envelope, or bulb) with a filament of tungsten wire inside the bulb, through which an electric current is passed. Contact wires and a base with two (or more) conductors provide electrical connections to the filament. Incandescent light bulbs usually contain a stem or glass mount anchored to the bulb's base which allows the electrical contacts to run through the envelope without gas/air leaks. Small wires embedded in the stem in turn support the filament and/or its lead wires. The bulb is filled with an inert gas such as argon to reduce evaporation of the filament. An electrical current heats the filament to typically 2000 K to 3300 K (about 3100-5400°F), well below tungsten's melting point of 3695 K (6192°F). Filament temperatures depend on the filament type, shape, size, and amount of current drawn. The heated filament emits light that approximates a continuous spectrum. The useful part of the emitted energy is visible light, but most energy is given off as heat in the near-infrared wavelengths. Three-way light bulbs have two filaments and three conducting contacts in their bases. The filaments share a common ground, and can be lit separately or together. Common wattages include 30-70-100, 50-100-150, and 100-200-300, with the first two numbers referring to the individual filaments, and the third giving the combined wattage. While most light bulbs have clear or frosted glass, other kinds are also produced, including the various colors used for Christmas tree lights and other decorative
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lighting. Neodymium-containing glass is sometimes used to provide a more natural-appearing light.
1. Outline of Glass bulb 2. Low pressure inert gas (argon, neon, nitrogen) 3. Tungsten filament 4. Contact wire (goes out of stem) 5. Contact wire (goes into stem) 6. Support wires 7. Stem (glass mount) 8. Contact wire (goes out of stem) 9. Cap (sleeve) 10. Insulation 11. Electrical contact
Fig 3.2 INCANDESCENT LAMP
Many arrangements of electrical contacts are used. Large lamps may have a screw base (one or more contacts at the tip, one at the shell) or a bayonet base (one or more contacts on the base, shell used as a contact or used only as a mechanical support). Some tubular lamps have an electrical contact at either end. Miniature lamps may have a wedge base and wire contacts, and some automotive and special purpose lamps have screw terminals for connection to wires.
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Contacts in the lamp socket allow the electric current to pass through the base to the filament. Power ratings for incandescent light bulbs range from about 0.1 watt to about 10,000 watts. The glass bulb of a general service lamp can reach temperatures between 200 and 260 degrees Celsius (400 to 550 degrees Fahrenheit). Lamps intended for high power operation or used for heating purposes will have envelopes made of hard glass or fused quartz.
3.3 SUMMARY: In this chapter a detailed study on the introduction and construction of Incandescent lamp. The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence (a general term for heat-driven light emissions which includes the simple case of black body radiation). An electric current passes through a thin filament, heating it until it produces light.
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CHAPTER 4 BLOCK DIAGRAM OF CLAP SWITCH 4.1 INTRODUCTION: In this chapter we will be studying block diagram of clap switch and hardware components. Power supply consists of one half wave rectifier. A rectifier is an electrical device that converts alternating current (AC) to direct current. This circuit uses half wave rectifier.
4.2 BLOCK DIAGRAM OF CLAP SWITCH:
POWER SUPPLY
AMPLIFIE R
FLIPFLOP
MIC RELAY
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Fig 4.2 BLOCK DIAGRAM OF CLAP SWITCH
4.3 POWER SUPPLY: Power supply consists of one half wave rectifier. A rectifier is an electrical device that converts alternating current (AC) to direct current. This circuit uses half wave rectifier. Power supply is a supply of power electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to others.
4.4 RELAY: 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 to be, in a broad sense, a form of an electrical amplifier. Many relays use an electromagnet to operate a switching mechanism, but other operating principles are also used. Relays find applications where it is necessary to control a circuit by a low-power signal, or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another. Relays found extensive use in telephone exchanges and early computers to perform logical operations. A type of relay that can handle the high power required to directly drive an electric motor is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical
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circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protection relays".
4.4.1 BASIC DESIGN AND OPERATION:
Fig 4.4.1 SPDT Relay
A simple electromagnetic relay, such as the one taken from a car in the first picture, is an adaptation of an electromagnet. It consists of a coil of wire surrounding a soft iron core, an iron yoke, which provides a low reluctance path for magnetic flux, a moveable iron armature, and a set, or sets, of contacts; two in the relay pictured. The armature is hinged to the yoke and mechanically linked to a moving contact or contacts. It is held in place by a spring so that when the relay is de-energized there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts in the relay pictured is closed, and the other set is open. Other relays may have more or fewer sets of contacts depending on their function. The relay in the picture also has a wire connecting the armature to the yoke. 26
This ensures continuity of the circuit between the moving contacts on the armature, and the circuit track on the Printed Circuit Board (PCB) via the yoke, which is soldered to the PCB.
4.5 MICROPHONE: A microphone, sometimes colloquially called a mic or mike, is an acoustic-toelectric transducer or sensor that converts sound into an electrical signal. Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production, live and recorded audio engineering, in radio and television broadcasting and in computers for recording voice, VoIP, and for non-acoustic purposes such as ultrasonic checking. Most microphones today use electromagnetic induction (dynamic microphone), capacitance change (condenser microphone, pictured right), piezoelectric generation, or light modulation to produce an electrical voltage signal from mechanical vibration. 4.5.1 CONDENSER, CAPACITOR OR ELECTROSTATIC MICROPHONE:
Fig 4.5.1 CONDENSER, CAPACITOR OR ELECTROSTATIC MICROPHONE
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In a condenser microphone, also known as a capacitor microphone, the diaphragm acts as one plate of a capacitor, and the vibrations produce changes in the distance between the plates. There are two methods of extracting an audio output from the transducer thus formed: DC-biased and radio frequency (RF) or high frequency (HF) condenser microphones. With a DC-biased microphone, the plates are biased with a fixed charge (Q). The voltage maintained across the capacitor plates changes with the vibrations in the air, according to the capacitance equation (C = Q / V), where Q = charge in coulombs, C = capacitance in farad and V = potential difference in volts. The capacitance of the plates is inversely proportional to the distance between them for a parallel-plate capacitor. A nearly constant charge is maintained on the capacitor. As the capacitance changes, the charge across the capacitor does change very slightly, but at audible frequencies it is sensibly constant. The capacitance of the capsule and the value of the bias resistor form a filter which is high pass for the audio signal, and low pass for the bias voltage. Note that the time constant of an RC circuit equals the product of the resistance and capacitance. Within the time-frame of the capacitance change (on the order of 100 μs), the charge thus appears practically constant and the voltage across the capacitor changes instantaneously to reflect the change in capacitance. The voltage across the capacitor varies above and below the bias voltage. The voltage difference between the bias and the capacitor is seen across the series resistor. The voltage across the resistor is amplified for performance or recording.RF condenser microphones use a comparatively low RF voltage, generated by a lownoise oscillator. The oscillator may either be frequency modulated by the capacitance changes produced by the sound waves moving the capsule diaphragm, or the capsule may be part of a resonant circuit that modulates the amplitude of the fixed-frequency oscillator signal. Demodulation yields a low-noise audio frequency signal with very low source impedance. This technique permits the use of a diaphragm with looser tension, which may be used to achieve better low-frequency response. 28
The RF biasing process results in a lower electrical impedance capsule, a useful byproduct of which is that RF condenser microphones can be operated in damp weather conditions which would effectively short out a DC-biased microphone. The Sennheiser "MKH" series of microphones use the RF biasing technique. Condenser microphones span the range from inexpensive karaoke microphones to high-fidelity recording microphones. They generally produce a high-quality audio signal and are now the popular choice in laboratory and studio recording applications. They require a power source, provided either from microphone inputs as phantom power or from a small battery. Power is necessary for establishing the capacitor plate voltage, and is also needed for internal amplification of the signal to a useful output level. Condenser microphones are also available with two diaphragms, the signals from which can be electrically connected such as to provide a range of polar patterns (see below), such as cardioids, Omni directional and figure-eight. It is also possible to vary the pattern smoothly with some microphones, for example the Rode NT2000 or CAD M179.
4.6 SUMMARY: In this chapter a detailed study on block diagram of clap switch and hardware components. Power supply consists of one half wave rectifier. A rectifier is an electrical device that converts alternating current (AC) to direct current.
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CHAPTER 5 FABRICATION OF THE PROJECT 5.1 INTRODUCTION: In this chapter we will be studying circuit diagram of clap switch and hardware components. 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.
5.2 CIRCUIT DIAGRAM OF CLAP SWITCH:
Fig 5.2 Circuit Diagram of Clap Switch
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5.2.1 COMPONENTS USED: RESISTORS: 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 CAPACITORS: C1 0.01UF C2, 3 0.047UF C4 1000UF/16V SEMI CONDUCTORS: Q1, 2, 3, 4 BC 149 D1 IN 4002 D2, 3, 4, 5 IN 4148 TRANSFORMER 12V/300mA CONDENSER MIC RELAY 12V single charge over relay
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5.2.2 CIRCUIT OPERATION: The sound of clap is received by a small microphone that is shown biased by resistor R1 in the circuit. The signal is further amplified by transistors Q1, Q2, Q3.The sound of clap is received by a small microphone. 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 flipflop 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 like a mechanical switch. . With the help of a relay it is easy for connecting any number of electrical appliances. The relay contact is connected to the power line and hence turns on/off any electrical appliance connected all the way through relay.
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5.3 HARDWARE DESCRIPTION: 5.3.1 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. The primary characteristics of a resistor are the resistance, the tolerance, maximum working voltage and the power rating. 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 depends upon the materials constituting the resistor as well as its physical dimensions; it's determined by design. 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. 5.3.2 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. 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.
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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 the flow of 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. 5.3.3 DIODE: 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. The most common function of a diode is to allow an electric current 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 extract modulation from radio signals in radio receivers.
5.3.4 TRANSISTOR:
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. 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.
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Transistors may be packaged individually or as part of an integrated circuit, some with over a billion transistors in a very small area.
5.4 ADVANTAGES OF CLAP SWITCH: •
Low cost
•
Simple design
•
Adjust the sensitivity of this circuit to control a Relay that can turn on whatever is connected to the contacts of the relay.
•
Turn on a light when your dog barks or set of a siren when an intruder makes
5.4.1 DISADVANTAGES OF CLAP SWITCH: •
You need only a sharp sound to trigger the switch.
•
Standard clap switch offers little security. Anyone who can clap, or even click there fingers or shout can trigger the switch
•
Unless a clap switch is adjusted to respond only to hard, sharp claps, it is likely to be triggered by a variety of unwanted sounds. This also means that “lighter” sounds, such as a clicking of one’s fingers, or tapping a pencil on a desk, are less likely to trigger
5.4.2 APPLICATIONS OF CLAP SWITCH: •
This circuit can be used to switch on and off a light, a fan, a radio or a TV by the sound
•
You have one in your bed room, throw a ball against the wall, or sneeze, and the light
of a clap.
goes out! Similarly, a bump in the night can turn the light on.
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5.5 SUMMARY: In this chapter a detailed study on circuit diagram of clap switch and hardware components. 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.
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CHAPTER 6 CONCLUSION 6.1 CONCLUSIONS: 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 TV. etc using this converted electrical energy which is used to turn on relay (an electronic switch). To conclude my project I think that I have carried it out to a reasonably high level. I am glad that my build has worked and although problematic set backs I have had reasonable time to conclude the end of my project Other improvements that could have been made include, the overall size of the board although it is small and reasonable it would be ideal to get it even smaller so it could fit into other products such as desk lamps, toys and other ranges of products. I have not been able to case my product up as of yet but I am planning to build it in you some kind of desk lamp that I could use my self, I think it would be a good “party piece” and novelty item.
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6.2 FUTURE ENHANCEMENTS: This project can be enhanced for the “stock standard” clap-switch has a number of distinct shortcomings. If for example you have one in your bed room, throw a ball against the wall, or sneeze, and the light goes out! Similarly, a bump in the night can turn the light on. Any number of sharp sounds can switch the clap-switch either on or off. A second shortcoming is that, unless a clap switch is adjusted to respond only to hard, sharp claps, it is likely to be triggered by a variety of unwanted sounds. This also means that “lighter” sounds, such as a clicking of one’s fingers, or tapping a pencil on a desk, are less likely to trigger a “stock standard” clap switch. Instead, far loader, disruptive sounds are required. A third shortcoming is that the standard clap switch offers little security. Anyone who can clap, or even click there fingers or shout, can trigger the switch. In brief, the multi-clap switch may be activated with one to nine claps, as preferred. The same number of claps is required to switch it off again. This it does with more then the usual sensitivity. The precise “speed” of the claps may also be set, so that the clapping either too fast or too slowly will reset the switch.
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REFERENCES: 1. http://www.csgnetwork.com/resistcolcalc.html 2. www.electronic-circuits-diagrams.com/. 3. www.electro-tech-online.com/electronic-books/ 4. http://www.kpsec.freeuk.com/components/relay.htm 5. http://www.physlink.com/education/askexperts/ae430.cfm. 6. ELECTRONICS FOR YOU. 7. EDC-SALIVAHANA 8. POWER ELECRONICS-V.K MEHTA 9. POWER SYSTEMS-C.L WADHWA
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