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ABSTRACT

The purpose of this project is to operate any home appliance using Remote Control.

The entire circuit works on the basis of Infrared rays (IR) .The output of the device becomes high or low in the

presence or absence of IR rays. When no IR rays fall on the receiver module the output remains high. The circuit

consists of two transistors t1 & t2 due to large base current ,the transistor t2 will remain in cut-off state .Thus the

remaining circuit and the load is in off condition.

Remote operating distance upto 30 feet/10 meters.When IR rays fall on the receiver module the t2 will

conduct energizing the relay2 thus ic2 triggers and output remains high.The main application of this project is to

on or off any home appliance using any remote in schools, offices and industries.It has advantages of

1.Sparkless and contact less switching increases switches life.

2.Prevents children from risk of electric shock and short circuit.

3.It is a boon for physically handicapped persons.

4.Ideal for bed-ridden patients and aged people

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CIRCUIT DIAGRAM:

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CIRCUIT DESCRIPTION:

This circuit is designed to switch on/off any home or industrial appliance by using the

TV/DVD remote controller. The circuit can be operated up to a distance of 5-10 metre depending on the

remote used. The circuit consists of a step-down transformer X1 (6V-0-6V, 250mA secondary), 5V

regulator 7805 (IC1), two 5V, 1 change over (C/O) relay, a timer NE555 IC (IC2), an IR receiver module

(IRX1 TSOP1738) and some discrete components. The circuit works on regulated 5V, which is derived

from X1 and regulated by IC1. Home appliance is controlled either by pressing any key on the remote or

by manually pressing switch s1 .

The TV/DVD remote controller produces 38kHz frequency. The IR receiver module operates at

this frequency. It is used to control relay RL2. The relay triggers IC2, which is wired in a bistable mode

to control the home appliance connected at the contacts of relay RL1. Timer IC2 toggles relay RL1 when

switch S1 is pressed momentarily. Threshold and trigger input pins 6 and 2 of IC2 are held at one-half of

the power supply voltage (5V) by resistors R2 and R3. When output pin 3 of IC2 is high, capacitor C4

charges. .

When switch S1 is pressed, capacitor C4 voltage is applied to pins 2 and 6 of IC2, which causes

the output of IC2 to change from low to high, or high to low. When switch S1 is released capacitor C4

charges or discharges to the original level at the output pin 3 of IC2. At normal condition, when IR rays

are not incident on TSOP1738, its output at pin 3 remains high. When any TV remote key is pressed, IR

rays fall on the TSOP1738 and its output goes low. At the same time relay RL2 energises for a few

seconds through pnp transistor T2 (BC558). The working of the circuit is simple.

Initially, when there are no IR rays falling on the IR receiver module, its output remains high.

Transistor T2 is in cut-off condition. Relay RL2 does not energise and hence IC2 does not toggle. As a

result home appliance connected at the contacts of relay RL1 remains switched off. When you press any

remote key for the first time, IR receiver module’s output goes low and collector of the transistor T2 goes

high. Relay RL2 energises and triggers IC2. Output of IC2 goes high and relay RL1 energises to switch

on the appliance. So the appliance which is connected at the contacts of relay RL1 remains switched on.

Now when you press any remote key the second time, relay RL2 energises and re-triggers IC2. Output of

IC2 goes low and relay RL1 de-energises to switch off the appliance. Once relay RL1 de-energises it

remains in that state.

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555 IC :

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation and oscillator

applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element.

Derivatives provide up to four timing circuits in one package.

Introduced in 1971 by Signetics, the 555 is still in widespread use, thanks to its ease of use, low price and

good stability, and is now made by many companies in the original bipolar and also in low-power CMOS

types. As of 2003, it was estimated that 1 billion units are manufactured every year.

The IC was designed in 1971 by Hans R. Camenzind under contract to Signetics, which was later

acquired by Philips.

Depending on the manufacturer, the standard 555 package includes 25 transistors, 2 diodes and 15

resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8).[2] Variants available

include the 556 (a 14-pin DIP combining two 555s on one chip), and the two 558 & 559s (both a 16-pin

DIP combining four slightly modified 555s with DIS & THR connected internally, and TR is falling edge

sensitive instead of level sensitive). There is no 557.

The NE555 parts were commercial temperature range, 0 °C to +70 °C, and the SE555 part number

designated the military temperature range, −55 °C to +125 °C. These were available in both

highreliability metal can (T package) and inexpensive epoxy plastic (V package) packages. Thus the full

part numbers were NE555V, NE555T, SE555V, and SE555T. It has been hypothesized that the 555 got

its name from the three 5 kΩ resistors used within, but Hans Camenzind has stated that the number was

arbitrary.

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Low power versions of the 555 are also available, such as the 7555 and CMOS TLC555. The 7555 is

designed to cause less supply glitching than the classic 555 and the manufacturer claims that it usually

does not require a "control" capacitor and in many cases does not require a decoupling capacitor on the

power supply. Such a practice should nevertheless be avoided, because noise produced by the timer or

variation in power supply voltage might interfere with other parts of a circuit or influence its threshold

voltages.

Usage Pins :

The connection of the pins for a DIP package is as follows:

Pin Name Purpose1 GND Ground, low level (0 V)

2 TRIG OUT rises, and interval starts, when this input falls below 1/3 VCC.

3 OUT This output is driven to +VCC or GND.

4 RESET A timing interval may be interrupted by driving this input to GND.

5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).

6 THR The interval ends when the voltage at THR is greater than at CTRL.

7 DIS Open collector output; may discharge a capacitor between intervals.

8 V+, VCCPositive supply voltage is usually between 3 and 15 V.

The 555 has three operating modes:

Monostable mode: in this mode, the 555 functions as a "one-shot" pulse generator. Applications

include timers, missing pulse detection, bouncefree switches, touch switches, frequency divider,

capacitance measurement, pulse-width modulation (PWM) and so on.

Astable: free running mode: the 555 can operate as an oscillator. Uses include LED and lamp

flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position

modulation and so on. Selecting a thermistor as timing resistor allows the use of the 555 in a

temperature sensor: the period of the output pulse is determined by the temperature. The use of a

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microprocessor based circuit can then convert the pulse period to temperature, linearize it and

even provide calibration means.

Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not

connected and no capacitor is used. Uses include bounce-free latched switches.

Monostable:

The relationships of the trigger signal, the voltage on C and the pulse width in monostable mode

In the monostable mode, the 555 timer acts as a "one-shot" pulse generator. The pulse begins when the

555 timer receives a signal at the trigger input that falls below a third of the voltage supply. The width of

the output pulse is determined by the time constant of an RC network, which consists of a capacitor (C)

and a resistor (R). The output pulse ends when the voltage on the capacitor equals 2/3 of the supply

voltage. The output pulse width can be lengthened or shortened to the need of the specific application by

adjusting the values of R and C.

While using the timer IC in monostable mode, the main disadvantage is that the time span between the

two triggering pulses must be greater than the RC time constant.

Bistable

In bistable mode, the 555 timer acts as a basic flip-flop. The trigger and reset inputs (pins 2 and 4

respectively on a 555) are held high via Pull-up resistors while the threshold input (pin 6) is simply

grounded. Thus configured, pulling the trigger momentarily to ground acts as a 'set' and transitions the

output pin (pin 3) to Vcc (high state). Pulling the reset input to ground acts as a 'reset' and transitions the

output pin to ground (low state). No capacitors are required in a bistable configuration. Pin 5 (control) is

connected to ground via a small value capacitor (usually 0.01 to 0.1 uF); pin 7 (discharge) is left floating.

Astable

In astable mode, the 555 timer puts out a continuous stream of rectangular pulses having a specified

frequency. Resistor R1 is connected between VCC and the discharge pin (pin 7) and another resistor (R2) is

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connected between the discharge pin (pin 7), and the trigger (pin 2) and threshold (pin 6) pins that share a

common node. Hence the capacitor is charged through R1 and R2, and discharged only through R2, since

pin 7 has low impedance to ground during output low intervals of the cycle, therefore discharging the

capacitor.

ICM7555 PIN DESCRIPTION:

The ICM7555 is a CMOS timer providing significantly improved performance over the

Standard NE/SE555 timer, while at the same time being a direct replacement for those devices in most

applications. The ICM7555 is a stable controller capable of producing accurate time delays or

frequencies.

PIN DIAGRAM :

OPERATION :

In this mode of operation, the timer functions as a one shot. Initially the external capacitor

(C) is held discharged by a transistor inside the timer. Upon application of a negative TRIGGER pulse to

pin 2, the internal flip-flop is set which releases the short circuit across the external capacitor and drives

the OUTPUT high. The voltage across the capacitor increases exponentially with a time constant

t = RC.When the voltage across the capacitor equals 2/3 V+, the comparator resets the flip-flop, which in

turn discharges the capacitor rapidly and also drives the OUTPUT to its low state.TRIGGER must return

to a high state before the OUTPUT can return to a low state.

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APPLICATIONS :

• Precision timing

• Pulse generation

• Sequential timing

• Time delay generation

• Pulse width modulation

• Pulse position modulation

• Missing pulse detector

RESISTORS :

Resistors (R), are the most commonly used of all electronic components, to the point where they are

almost taken for granted. They are "Passive Devices", that is they contain no source of power or

amplification but only attenuate or reduce the voltage signal passing through them. When used in DC

circuits the voltage drop produced is measured across their terminals as the circuit current flows through

them while in AC circuits the voltage and current are both in-phase producing 0 degrees phase shift. In

all Electrical and Electronic circuit diagrams and schematics, the most commonly used resistor symbol is

that of a "zig-zag" type line with the value of its resistance given in Ohms, Ω.

RESISTOR SYMBOL

The symbol used in schematic and electrical drawings for a Resistor can either be a

"zig- zag" type line or a rectangular box.

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RESISTOR TYPES

All modern resistors can be classified into four broad groups;

• Carbon Composition Resistor - Made of carbon dust or graphite paste, low wattage values

•Film or Cermet Resistor - Made from conductive metal oxide paste, very low wattage values

• Wire-Wound Resistors. - Metallic bodies for heat sink mounting, very high wattage ratings

•Semiconductor Resistors - High frequency/precision surface mount thin film technology

RESISTOR COLOUR CODE

The resistance value, tolerance, and watt rating of the resistor are generally printed onto the body of the

resistor as numbers or letters when the resistor is big enough to read the print, such as large power

resistors. When resistors are small such as 1/4W Carbon and Film types, these specifications must be

shown in some other manner as the print would be too small to read. So to overcome this, small resistors

use coloured painted bands to indicate both their resistive value and their tolerance with the physical size

of the resistor indicating its wattage rating. These coloured painted bands are generally known as a

Resistors Colour Code.

THE RESISTOR COLOUR CODE TABLE:

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VARIABLE RESISTOR:

Variable resistors consist of a resistance track with connections at both ends and a wiper which moves

along the track as you turn the spindle. The track may be made from carbon, cermet (ceramic and metal

mixture) or a coil of wire (for low resistances). The track is usually rotary but straight track versions,

usually called sliders, are also available. Variable are often called potentiometers in books and catalogues.

RHEOSTAT:

This is the simplest way of using a variable resistor. Two terminals are used: one connected to an end of

the track, the other to the movable wiper. Tuning the spindle changes the rheostat resistance between the

two terminals from zero up to the maximum resistance.

CAPACITORS :

INTRODUCTION

Just like the Resistor, the Capacitor or sometimes referred to as a Condenser is a passive device, and one

which stores energy in the form of an electrostatic field which produces a potential (Static Voltage)

across its plates. When a voltage is applied to these plates, a current flows charging up the plates with

electrons giving one plate a positive charge and the other plate an equal and opposite negative charge.

This flow of electrons to the plates is known as the Charging Current and continues to flow until the

voltage across the plates (and hence the capacitor) is equal to the applied voltage Vc. At this point the

capacitor is said to be fully charged and this is illustrated below.

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Capacitor Construction

Q = C x V

UNITS OF CAPACITANCE

Microfarad (μF) 1μF = 1/1,000,000 = 0.000001 = 10^-6 F

Nanofarad (nF) 1nF = 1/1,000,000,000 = 0.000000001 = 10^-9 F

Picofarad (pF) 1pF = 1/1,000,000,000,000 = 0.000000000001 = 10^-12 F

TYPES OF CAPACITORS

1.DIELECTRIC :

Dielectric Capacitors are usually of the variable type such as used for

tuning transmitters, receivers and transistor radios. They have a set of fixed plates and a set of

moving plates that mesh with the fixed plates and the position of the moving plates with respect to the

fixed plates determines the overall capacitance. The capacitance is generally at maximum when the

plates are fully meshed.

2. FILM CAPACITORS:

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Film Capacitors are the most commonly available of all types of capacitors,

consisting of a relatively large family of capacitors with the difference being in their dielectric properties.

These include polyester (Mylar), polystyrene, polypropylene, polycarbonate, metallized paper, teflon etc.

Film type capacitors are available in capacitance ranges from 5pF to 100uF depending upon the actual

type of capacitor and its voltage rating.

3. CERAMIC CAPACITORS :

Ceramic Capacitors or Disc Capacitors as they are generally called, are

made by coating two sides of a small porcelain or ceramic disc with silver and are then stacked together

to make a capacitor. For very low capacitance values a single ceramic disc of about 3-6mm is used.

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

capacitances can be obtained in a small physical size.

4. ELECTROLYTIC CAPACITORS

Electrolytic Capacitors are generally used when very large capacitance

values are required. Here instead of using a very thin metallic film layer for one of the electrodes, a semi-

liquid electrolyte solution in the form of a jelly or paste is used which serves as the second electrode

(usually the cathode). The dielectric is a very thin layer of oxide which is grown electro chemically in

production with the thickness of the film being less than ten microns. This insulating layer is so thin that

it is possible to make large value capacitors of a small size. The majority of electrolytic types of

capacitors are Polarized, that is the voltage applied to the capacitor terminals must be of the correct

polarity as an incorrect polarization will break down the insulating oxide layer and permanent damage

may result.

TRANSISTOR :

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A transistor is a semiconductor device used to amplify and switch electronic signals. It is made of a

solid piece of semiconductor material, with at least three terminals for connection to an external circuit. A

voltage or current applied to one pair of the transistor's terminals changes the current flowing through

another pair of terminals. Because the controlled (output) power can be much more than the controlling

(input) power, the transistor provides amplification of a signal. Some transistors are packaged

individually but many more are found embedded in integrated circuits.

TRANSISTOR CHARACTERISTICS:

ADVANTAGES

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The key advantages that have allowed transistors to replace their vacuum tube predecessors in Most applications are

• Small size and minimal weight, allowing the development of miniaturized electronic Devices.

• Highly automated manufacturing processes, resulting in low per-unit cost.

• Lower possible operating voltages, making transistors suitable for small, battery powered applications.

• Lower power dissipation and generally greater energy efficiency.

• Higher reliability and greater physical ruggedness.

• Extremely long life. Some transistorized devices have been in service for more than 30 years.

LIMITATIONS:

Silicon transistors do not operate at voltages higher than about 1,000 volts. In contrast

electron tubes have been developed that can be operated at tens of thousands of volts.

High power, high frequency operation, such as that can be used in over-the-air television

broadcasting, is better achieved in electron tubes due to improved electron mobility in

vacuum.

.

Diode

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A diode is a two-terminal electronic component that conducts electric current in only one direction. A

semiconductor diode is a crystalline piece of semiconductor material connected to two electrical

terminals. A vacuum tube diode 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

while blocking current in the opposite 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.

When p-type and n-type materials are placed in contact with each other, the junction is

depleted of charge carriers and behaves very differently than either type of material. The electrons in n-

type material diffuse across the junction and combines with holes in p-type material. The region of the p-

type material near the junction takes on a net negative charge because of the electrons attracted. Since

electrons departed the N-type region, it takes on a localized positive charge. The thin layer of the crystal

lattice between these charges has been depleted of majority carriers, thus, is known as the depletion

region. It becomes nonconductive intrinsic semiconductor material. This separation of charges at the p-n

junction constitutes a potential barrier, which must be overcome by an external voltage source to make

the junction conduct.

The electric field created by the space charge region opposes the diffusion process for both

electrons and holes. There are two concurrent phenomena: the diffusion process that tends to generate

more space charge and the electric field generated by the space charge that tends to counteract the

diffusion

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When the diode is forward biased, the positive charge applied to the P-type material repels the holes,

while the negative charge applied to the N-type material repels the electrons. As electrons and holes are

pushed towards the junction, the width of depletion zone decreases. This lowers the barrier in potential.

With increasing forward-bias voltage, the depletion zone eventually becomes thin enough that the electric

field of the zone can't counteract charge carrier motion across the p–n junction, consequently reducing

electrical resistance. The electrons which cross the p–n junction into the P-type material will diffuse in

the near-neutral region. Therefore, the amount of minority diffusion in the near-neutral zones determines

the amount of current that may flow through the diode.

When the diode is forward biased, the positive charge applied to the P-type material

repels the holes, while the negative charge applied to the N-type material repels the electrons. As

electrons and holes are pushed towards the junction, the width of depletion zone decreases. This lowers

the barrier in potential. With increasing forward-bias voltage, the depletion zone eventually becomes thin

enough that the electric field of the zone can't counteract charge carrier motion across the p–n junction,

consequently reducing electrical resistance. The electrons which cross the p–n junction into the P-type

material

will diffuse in the near-neutral region. Therefore, the amount of minority diffusion in the near-neutral

zones determines the amount of current that may flow through the diode.

RELAY:

A relay is an electrically operated switch. Many relays use an electromagnet to operate a

switching mechanism mechanically, but other operating principles are also used. Relays are used where it

is necessary to control a circuit by a low-power signal (with complete electrical isolation between control

and controlled circuits), 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 were used extensively in telephone exchanges and early computers to

perform logical operations.

A type of relay that can handle the high power required to directly control an electric motor or other loads

is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a

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semiconductor device to perform switching. Relays with calibrated operating characteristics and

sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in

modern electric power systems these functions are performed by digital instruments still called

"protective relays".

Basic design and operation:

Simple Electromechanical Relay.

A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core, an iron yoke

which provides a low reluctance path for magnetic flux, a movable iron armature, and one or more sets of

contacts (there are two in the relay pictured). The armature is hinged to the yoke and mechanically linked

to one or more sets of moving 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. 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.

When an electric current is passed through the coil it generates a magnetic field that activates the

armature, and the consequent movement of the movable contact(s) either makes or breaks (depending

upon construction) a connection with a fixed contact. If the set of contacts was closed when the relay was

de-energized, then the movement opens the contacts and breaks the connection, and vice versa if the

contacts were open. When the current to the coil is switched off, the armature is returned by a force,

approximately half as strong as the magnetic force, to its relaxed position. Usually this force is provided

by a spring, but gravity is also used commonly in industrial motor starters. Most relays are manufactured

to operate quickly. In a low-voltage application this reduces noise; in a high voltage or current

application it reduces arcing.

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When the coil is energized with direct current, a diode is often placed across the coil to dissipate the

energy from the collapsing magnetic field at deactivation, which would otherwise generate a voltage

spike dangerous to semiconductor circuit components. Some automotive relays include a diode inside the

relay case. Alternatively, a contact protection network consisting of a capacitor and resistor in series

(snubber circuit) may absorb the surge. If the coil is designed to be energized with alternating current

(AC), a small copper "shading ring" can be crimped to the end of the solenoid, creating a small out-of-

phase current which increases the minimum pull on the armature during the AC cycle.

A solid-state relay uses a thyristor or other solid-state switching device, activated by the control signal, to

switch the controlled load, instead of a solenoid. An optocoupler (a light-emitting diode (LED) coupled

with a photo transistor) can be used to isolate control and controlled circuits.

Latching relay

Latching relay with permanent magnet

A latching relay has two relaxed states (bistable). These are also called "impulse", "keep", or "stay"

relays. When the current is switched off, the relay remains in its last state. This is achieved with a

solenoid operating a ratchet and cam mechanism, or by having two opposing coils with an over-center

spring or permanent magnet to hold the armature and contacts in position while the coil is relaxed, or

with a permanent core. In the ratchet and cam example, the first pulse to the coil turns the relay on and

the second pulse turns it off. In the two coil example, a pulse to one coil turns the relay on and a pulse to

the opposite coil turns the relay off. This type of relay has the advantage that one coil consumes power

only for an instant, while it is being switched, and the relay contacts retain this setting across a power

outage.

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Machine tool relay:

A machine tool relay is a type standardized for industrial control of machine tools, transfer

machines, and other sequential control. They are characterized by a large number of contacts (sometimes

extendable in the field) which are easily converted from normally open to normally closed status, easily

replaceable coils, and a form factor that allows compactly installing many relays in a control panel.

Although such relays once were the backbone of automation in such industries as automobile assembly,

the Programmable Logic Controller (PLC) mostly displaced the machine tool relay from sequential

control applications.

A relay allows circuits to be switched by electrical equipment: for example, a timer circuit with a

relay could switch power at a preset time. For many years relays were the standard method of controlling

industrial electronic systems. A number of relays could be used together to carry out complex functions

(relay logic). The principle of relay logic is based on relays which energize and de-energize associated

contacts. Relay logic is the predecessor of ladder logic, which is commonly used in Programmable logic

controllers.

Contactor relay:

A contactor is a very heavy duty relay used for switching electric motors and lighting loads,

although contactors are not generally called relays. Continuous current ratings for common contactors

range from 10 amps to several hundred amps. High current contacts are made with alloys containing

silver. The unavoidable arcing causes the contacts to oxidize; however, silver oxide is still a good

conductor. Such devices are often used for motor starters. A motor starter is a contactor with overload

protection devices attached. The overload sensing devices are a form of heat operated relay where a coil

heats a bi-metal strip, or where a solder pot melts, releasing a spring to operate auxiliary contacts. These

auxiliary contacts are in series with the coil. If the overload senses excess current in the load, the coil is

de-energized. Contactor relays can be extremely loud to operate, making them unfit for use where noise

is a chief concern.

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Solid-state relay:

Solid state contactor is a heavy-duty solid state relay, including the necessary heat sink, used for switching

electric heaters, small electric motors and lighting loads; where frequent on/off cycles are required. There are no

moving parts to wear out and there is no contact bounce due to vibration.

They are activated by AC control signals or DC control signals from Programmable logic

controller (PLCs), PCs, Transistor-transistor logic (TTL) sources, or other microprocessor and

microcontroller controls.

Buchholz relay:

A Buchholz relay is a safety device sensing the accumulation of gas in large oil-filled

transformers, which will alarm on slow accumulation of gas or shut down the transformer if gas is

produced rapidly in the transformer oil.

Forced-guided contacts relay:

A forced-guided contacts relay has relay contacts that are mechanically linked together, so that

when the relay coil is energized or de-energized, all of the linked contacts move together. If one set of

contacts in the relay becomes immobilized, no other contact of the same relay will be able to move. The

function of forced-guided contacts is to enable the safety circuit to check the status of the relay. Forced-

guided contacts are also known as "positive-guided contacts", "captive contacts", "locked contacts", or

"safety relays".

Since relays are switches, the terminology applied to switches is also applied to relays. A relay will

switch one or more poles, each of whose contacts can be thrown by energizing the coil in one of three

ways:

Normally open (NO) contacts connect the circuit when the relay is activated; the circuit is

disconnected when the relay is inactive. It is also called a Form A contact or "make" contact. NO

contacts can also be distinguished as "early-make" or NOEM, which means that the contacts will close

before the button or switch is fully engaged.

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Normally-closed (NC) contacts disconnect the circuit when the relay is activated; the circuit is

connected when the relay is inactive. It is also called a Form B contact or "break" contact. NC contacts

can also be distinguished as "late-break" or NCLB, which means that the contacts will stay closed until

the button or switch is fully disengaged.

Change-over (CO), or double-throw (DT), contacts control two circuits: one normally-open

contact and one normally-closed contact with a common terminal. It is also called a Form C contact or

"transfer" contact ("break before make"). If this type of contact utilizes a "make before break"

functionality, then it is called a Form D contact.

The following designations are commonly encountered:

SPST – Single Pole Single Throw. These have two terminals which can be connected or

disconnected. Including two for the coil, such a relay has four terminals in total. It is ambiguous whether

the pole is normally open or normally closed. The terminology "SPNO" and "SPNC" is sometimes used

to resolve the ambiguity.

SPDT – Single Pole Double Throw. A common terminal connects to either of two others.

Including two for the coil, such a relay has five terminals in total.

DPST – Double Pole Single Throw. These have two pairs of terminals. Equivalent to two SPST

switches or relays actuated by a single coil. Including two for the coil, such a relay has six terminals in

total. The poles may be Form A or Form B (or one of each).

DPDT – Double Pole Double Throw. These have two rows of change-over terminals. Equivalent

to two SPDT switches or relays actuated by a single coil. Such a relay has eight terminals, including the

coil.

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TSOP 1738 RECEVIER MODULE :

Description:

The TSOP17.. – series are miniaturized receivers for infrared remote control systems. PIN diode and

preamplifier are assembled on lead frame, the epoxy package is designed as IR filter.The demodulated

output signal can directly be decoded by a microprocessor. TSOP17.. is the standard IR remote control

receiver series, supporting all major transmission codes.

Features:

1. Photo detector and preamplifier in one package

2. Internal filter for PCM frequency

3. Improved shielding against electrical field

Disturbance

4. TTL and CMOS compatibility

5. Output active low

6. Low power consumption

7. High immunity against ambient light

8. Continuous data transmission possible

(up to 2400 bps)

9. Suitable burst length

10. Cycles/burst

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Block Diagram:

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Suitable Data Format:

The circuit of the TSOP17 is designed in that way that unexpected output pulses due to noise or

disturbance signals are avoided. A bandpassfilter, an integrator stage and an automatic gain control are

used to suppress such disturbances. The distinguishing mark between data signal and disturbance signal

are carrier frequency, burst length and duty cycle.The data signal should fullfill the following condition:

Carrier frequency should be close to center frequency of the bandpass (e.g. 38kHz).

Burst length should be 10 cycles/burst or longer.

After each burst which is between 10 cycles and 70 cycles a gap time of at least 14 cycles is neccessary.

For each burst which is longer than 1.8ms a corresponding gap time is necessary at some time in the data

stream. This gap time should have at least same length as the burst.

Up to 1400 short bursts per second can be received continuously.

Some examples for suitable data format are:

NEC Code, Toshiba Micom Format, Sharp Code, RC5Code, RC6 Code, R–2000 Code, Sony Format

(SIRCS).

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When a disturbance signal is applied to the TSOP17 it can still receive the data signal. However the

sensitivity is reduced to that level that no unexpected pulses will occur.

Some examples for such disturbance signals which are suppressed by the TSOP17 are:

DC light (e.g. from tungsten bulb or sunlight)

Continuous signal at 38kHz or at any other frequency

Signals from fluorescent lamps with electronic ballast (an example of the signal modulation is in the

figure below).

TYPICAL CHARACTERISTICS:

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REMOTE:.

A  remote control  is a component of an electronics device, most commonly a television set, DVD

player and home theater systems originally used for operating the television device wirelessly from a

short line-of-sight distance..

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The main remote control technology used in the home is infrared. The signal between a remote control

handset and the device it is controlling are infrared pulses, which are invisible to the human eye. The

transmitter in the remote control handset sends out a pulse of infrared light when a button is pressed on

the handset. A transmitter is often a Light Emitting Diode (LED) which is built into the pointing end of

the remote control handset. The infrared light pulse represents a binary code that corresponds to a certain

command, such as (power on). The receiver passes the code to a microprocessor, which decodes it and

carries out the command. 

The remote control is usually contracted to remote. It is known by many other names as well, such

as converter, clicker, the box, flipper, the tuner, "the zapper", the changer, or the button. Commonly,

remote controls are Consumer IR devices used to issue commands from a distance to televisions or

other consumer electronics such as stereo systems, DVD players and dimmers. Remote controls for these

devices are usually small wireless handheld objects with an array of buttons for adjusting various settings

such as television channel, track number, and volume. Most of these remotes communicate to their

respective devices via infrared (IR) signals and a few via radio signals. Earlier remote controls in the

1970s used ultrasonic tones. Television IR signals can be mimicked by a universal remote, which is able

to emulate the functionality of most major brand television remote controls.

CONCLUSION:

The aim of the project work in the curriculum is to give an opportunity to utilize the knowledge and

skills gained in the class room and to apply the same to practical situation.

 

We are proud to say that we could be able to utilize the knowledge and skills obtained for the last three

years and could do the project of REMOTE CONTROL FOR HOME APPLIANCE successfully. This gives us

confidence and goes along with in making our future career a bright and prospective one.

Remote control can be widely used in all home appliances, hospitals, restaurants, offices etc.,The main

function of this device depends on IR rays but the circuit has disadvantage that it can disturb the operation of

other device when a device is in operation

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BIBLIOGRAPHY:

The IRS 12 architecture and applications- Kenneth J.Ayala

Electronic Components-D.V.Prasad

Wireless communications

-William C.Y.Lee

www.freedatasheets.com www.extremecircuits.net www.electronicsforu.net

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