wireless music transmission and reception by ir · web viewindex abstract block diagram...

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WIRELESS MUSIC TRANSMISSION AND RECEPTION BY IR COMMUNICATION

Wireless Music transmission and reception by IR communication

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INDEX1. ABSTRACT

2. BLOCK DIAGRAM

3. HARDWARE EXPLNATION

4. MELODY GENERATOR

5. IR

6. TRANSISTOR DRIVER CIRCUIT

7. SIREN

8. APPLICATIONS

9. ADVANTAGES

10. CONCLUSION

11. REFERENCES


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ABSTRACT


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ABSTRACT:

By using this project audio musical notes can be generated and heard up to a distance of

10 meters. The circuit can be divided into two parts: IR music transmitter and receiver.

The IR music transmitter works off a 9V battery, while the IR music receiver works off

regulated 9V to 12V. The transmitter uses popular melody generator IC UM66 that can

continuously generate musical tones. The output of this music melody generator is fed to

the IR driver stage to get the maximum range.

An LED is connected in the Transmitter section. This LED flickers according to the

musical tones generated by UM66 IC, indicating modulation. Two IR LEDs are

connected in series. For maximum sound transmission these should be oriented towards

IR phototransistor L14F1. The IR music receiver uses popular op-amp IC μA741 and

audio-frequency amplifier IC LM386 along with phototransistor L14F1 and some

discrete components. The melody generated by IC UM66 is transmitted through IR

LEDs, received by phototransistor and fed to pin 2 of IC μA741. Its gain can be varied

using potentiometer VR1. The output

of IC μA741 is fed to IC LM386 via capacitor C5 and potentiometer. The melody

produced is heard through the receiver’s loudspeaker. Potentiometer VR2 is used to

control the volume of loudspeaker (8-ohm, 1W). Switching off the power supply stops

melody generation.

This project uses regulated 9V, 750mA power supply. 7805 three terminal voltage

regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify

the ac out put of secondary of 230/18V step down transformer.


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Melody Generator

3.3V regulator

Transistor DriverStage - I

Transistor DriverStage - II

LED Music flicker indicator

IR LED

Power supply to all sections

Step down T/F

Bridge Rectifier

Filter Circuit Regulator

Transmitter: Wireless Music transmission and reception by IR communication

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Power supply to all sections

Step down T/F

Bridge Rectifier

Filter Circuit Regulator

Receiver: Wireless Music transmission and reception by IR communication

Audio AmplifierStage - I

Photo Transistor

Audio AmplifierStage - II

Loud speaker

Gain control Gain control

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HARDWARE EXPLANATION


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Hardware Explanation:

RESISTOR:

Resistors "Resist" the flow of electrical current. The higher the value of resistance

(measured in ohms) the lower the current will be. Resistance is the property of a

component which restricts the flow of electric current. Energy is used up as the voltage

across the component drives the current through it and this energy appears as heat in the

component.

Colour Code:


http://www.the12volt.com/ohm/ohmslaw.asp

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CAPACITOR:

Capacitors store electric charge. They are used with resistors

in timing circuits because it takes time for a capacitor to fill with charge. They are used

to smooth varying DC supplies by acting as a reservoir of charge. They are also used in

filter circuits because capacitors easily pass AC (changing) signals but they block DC

(constant) signals.

Circuit symbol:

Electrolytic capacitors are polarized and they must be connected the correct way

round, at least one of their leads will be marked + or -.

Examples:

DIODES:

Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol

shows the direction in which the current can flow. Diodes are the electrical version of a

valve and early diodes were actually called valves.

Circuit symbol:


http://www.kpsec.freeuk.com/powersup.htm#smoothing

http://www.kpsec.freeuk.com/555timer.htm

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Diodes must be connected the correct way round, the diagram may be

labeled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode!). The

cathode is marked by a line painted on the body. Diodes are labeled with their code in

small print; you may need a magnifying glass to read this on

small signal diodes.

Example:

LIGHT-EMITTING DIODE (LED):

The longer lead is the anode (+) and the shorter lead is the cathode (&minus). In the

schematic symbol for an LED (bottom), the anode is on the left and the cathode is on the

right. Lighemitting diodes are elements for light signalization in electronics.


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They are manufactured in different shapes, colors and sizes. For their low price,

low consumption and simple use, they have almost completely pushed aside other light

sources- bulbs at first place.

It is important to know that each diode will be immediately destroyed unless its current is

limited. This means that a conductor must be connected in parallel to a diode. In order to

correctly determine value of this conductor, it is necessary to know diode’s voltage drop

in forward direction, which depends on what material a diode is made of and what colors

it is. Values typical for the most frequently used diodes are shown in table below: As

seen, there are three main types of LEDs. Standard ones get full brightness at current of

20mA. Low Current diodes get full brightness at ten time’s lower current while Super

Bright diodes produce more intensive light than Standard ones.

Since the 8052 microcontrollers can provide only low input current and since their

pins are configured as outputs when voltage level on them is equal to 0, direct

confectioning to LEDs is carried out as it is shown on figure (Low current LED, cathode

is connected to output pin).

Switches and Pushbuttons:

A push button switch is used to either close or open an electrical circuit depending

on the application. Push button switches are used in various applications such as

industrial equipment control handles, outdoor controls, mobile communication terminals,

and medical equipment, and etc. Push button switches generally include a push button

disposed within a housing. The push button may be depressed to cause movement of the

push button relative to the housing for directly or indirectly changing the state of an

electrical contact to open or close the contact. Also included in a pushbutton switch may


http://www.electronics-manufacturers.com/products/relays-switches/push-button-switch/

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be an actuator, driver, or plunger of some type that is situated within a switch housing

having at least two contacts in communication with an electrical circuit within which the

switch is incorporated.

Typical actuators used for contact switches include spring loaded force cap actuators

that reciprocate within a sleeve disposed within the canister. The actuator is typically

coupled to the movement of the cap assembly, such that the actuator translates in a

direction that is parallel with the cap. A push button switch for a data input unit for a

mobile communication device such as a cellular phone, a key board for a personal

computer or the like is generally constructed by mounting a cover member directly on a

circuit board. Printed circuit board (PCB) mounted pushbutton switches are an

inexpensive means of providing an operator interface on industrial control products. In

such push button switches, a substrate which includes a plurality of movable sections is

formed of a rubber elastomeric. The key top is formed on a top surface thereof with a

figure, a character or the like by printing, to thereby provide a cover member. Push button

switches incorporating lighted displays have been used in a variety of applications. Such

switches are typically comprised of a pushbutton, an opaque legend plate, and a back

light to illuminate the legend plate.





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Block Diagram For Regulated Power Supply (RPS):

Figure: Power Supply

Description :

Transformer

A transformer is a device that transfers electrical energy from one circuit to another

through inductively coupled conductors—the transformer's coils. A varying current in the

first or primary winding creates a varying magnetic flux in the transformer's core, and

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

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

effect is called mutual induction.

Figure: Transformer Symbol

(or)

Transformer is a device that converts the one form energy to another form of energy like

a transducer.


http://en.wikipedia.org/wiki/Mutual_induction

http://en.wikipedia.org/wiki/Volt

http://en.wikipedia.org/wiki/Electromotive_force

http://en.wikipedia.org/wiki/Electromagnetic_induction

http://en.wikipedia.org/wiki/Magnetic_field

http://en.wikipedia.org/wiki/Magnetic_flux

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Inductive_coupling

http://en.wikipedia.org/wiki/Electrical_network

http://en.wikipedia.org/wiki/Electrical_energy

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Figure: Transformer

Basic Principle

A transformer makes use of Faraday's law and the ferromagnetic properties of an iron

core to efficiently raise or lower AC voltages. It of course cannot increase power so that

if the voltage is raised, the current is proportionally lowered and vice versa.


http://hyperphysics.phy-astr.gsu.edu/hbase/electric/powerac.html#c1

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/elemag.html#c4

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/elemag.html#c4

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/ferro.html#c4

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html#c1

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Figure: Basic Principle

Transformer Working

A transformer consists of two coils (often called 'windings') linked by an iron core, as

shown in figure below. There is no electrical connection between the coils; instead they

are linked by a magnetic field created in the core.

Figure: Basic Transformer


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Transformers are used to convert electricity from one voltage to another with minimal

loss of power. They only work with AC (alternating current) because they require a

changing magnetic field to be created in their core. Transformers can increase voltage

(step-up) as well as reduce voltage (step-down).

Alternating current flowing in the primary (input) coil creates a continually changing

magnetic field in the iron core. This field also passes through the secondary (output) coil

and the changing strength of the magnetic field induces an alternating voltage in the

secondary coil. If the secondary coil is connected to a load the induced voltage will make

an induced current flow. The correct term for the induced voltage is 'induced

electromotive force' which is usually abbreviated to induced e.m.f.

The iron core is laminated to prevent 'eddy currents' flowing in the core. These are

currents produced by the alternating magnetic field inducing a small voltage in the core,

just like that induced in the secondary coil. Eddy currents waste power by needlessly

heating up the core but they are reduced to a negligible amount by laminating the iron

because this increases the electrical resistance of the core without affecting its magnetic

properties.

Transformers have two great advantages over other methods of changing voltage:

1. They provide total electrical isolation between the input and output, so they can

be safely used to reduce the high voltage of the mains supply.

2. Almost no power is wasted in a transformer. They have a high efficiency (power

out / power in) of 95% or more.


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Classification of Transformer

Step-Up Transformer

Step-Down Transformer

Step-Down Transformer

Step down transformers are designed to reduce electrical voltage. Their primary voltage

is greater than their secondary voltage. This kind of transformer "steps down" the voltage

applied to it. For instance, a step down transformer is needed to use a 110v product in a

country with a 220v supply.

Step down transformers convert electrical voltage from one level or phase configuration

usually down to a lower level. They can include features for electrical isolation, power

distribution, and control and instrumentation applications. Step down transformers

typically rely on the principle of magnetic induction between coils to convert voltage

and/or current levels.

Step down transformers are made from two or more coils of insulated wire wound around

a core made of iron. When voltage is applied to one coil (frequently called the primary or

input) it magnetizes the iron core, which induces a voltage in the other coil, (frequently

called the secondary or output). The turn’s ratio of the two sets of windings determines

the amount of voltage transformation.

Figure: Step-Down Transformer


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An example of this would be: 100 turns on the primary and 50 turns on the secondary, a ratio of 2 to 1.

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

With step down transformers the voltage ratio between primary and secondary will mirror

the "turn’s ratio" (except for single phase smaller than 1 kva which have compensated

secondary). A practical application of this 2 to 1 turn’s ratio would be a 480 to 240

voltage step down. Note that if the input were 440 volts then the output would be 220

volts. The ratio between input and output voltage will stay constant. Transformers should

not be operated at voltages higher than the nameplate rating, but may be operated at

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

applications using standard transformers.

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

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

sized less than 1 KVA should not be reverse connected because the secondary windings

have additional turns to overcome a voltage drop when the load is applied. If reverse

connected, the output voltage will be less than desired.)

Step-Up Transformer

A step up transformer has more turns of wire on the secondary coil, which makes a larger

induced voltage in the secondary coil. It is called a step up transformer because the

voltage output is larger than the voltage input.

Step-up transformer 110v 220v design is one whose secondary voltage is greater than its

primary voltage. This kind of transformer "steps up" the voltage applied to it. For

instance, a step up transformer is needed to use a 220v product in a country with a 110v

supply.

A step up transformer 110v 220v converts alternating current (AC) from one voltage to

another voltage. It has no moving parts and works on a magnetic induction principle; it


http://www.gcsescience.com/pme16.htm

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can be designed to "step-up" or "step-down" voltage. So a step up transformer increases

the voltage and a step down transformer decreases the voltage.

The primary components for voltage transformation are the step up transformer core and

coil. The insulation is placed between the turns of wire to prevent shorting to one another

or to ground. This is typically comprised of Mylar, nomex, Kraft paper, varnish, or other

materials. As a transformer has no moving parts, it will typically have a life expectancy

between 20 and 25 years.

Figure: Step-Up Transformer

Applications :

Generally these Step-Up Transformers are used in industries applications only.

Types of Transformer

Mains Transformers

Mains transformers are the most common type. They are designed to reduce the AC

mains supply voltage (230-240V in the UK or 115-120V in some countries) to a safer

low voltage. The standard mains supply voltages are officially 115V and 230V, but

120V and 240V are the values usually quoted and the difference is of no significance in

most cases.


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Figure: Main Transformer

To allow for the two supply voltages mains transformers usually have two separate

primary coils (windings) labeled 0-120V and 0-120V. The two coils are connected in

series for 240V (figure 2a) and in parallel for 120V (figure 2b). They must be wired the

correct way round as shown in the diagrams because the coils must be connected in the

correct sense (direction):

Most mains transformers have two separate secondary coils (e.g. labeled 0-9V, 0-9V)

which may be used separately to give two independent supplies, or connected in series to

create a center-tapped coil (see below) or one coil with double the voltage.

Some mains transformers have a centre-tap halfway through the secondary coil and they

are labeled 9-0-9V for example. They can be used to produce full-wave rectified DC with

just two diodes, unlike a standard secondary coil which requires four diodes to produce

full-wave rectified DC.


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A mains transformer is specified by:

1. Its secondary (output) voltages Vs.

2. Its maximum power, Pmax, which the transformer can pass, quoted in VA (volt-

amp). This determines the maximum output (secondary) current, Imax...

...where Vs is the secondary voltage. If there are two secondary coils the

maximum power should be halved to give the maximum for each coil.

3. Its construction - it may be PCB-mounting, chassis mounting (with solder tag

connections) or toroidal (a high quality design).

Audio Transformers

Audio transformers are used to convert the moderate voltage, low current output of an

audio amplifier to the low voltage, high current required by a loudspeaker. This use is

called 'impedance matching' because it is matching the high impedance output of the

amplifier to the low impedance of the loudspeaker.

Figure: Audio transformer

Radio Transformers

Radio transformers are used in tuning circuits. They are smaller than mains and audio

transformers and they have adjustable ferrite cores made of iron dust. The ferrite cores

can be adjusted with a non-magnetic plastic tool like a small screwdriver. The whole

transformer is enclosed in an aluminum can which acts as a shield, preventing the

transformer radiating too much electrical noise to other parts of the circuit.


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Figure: Radio Transformer

Turns Ratio and Voltage

The ratio of the number of turns on the primary and secondary coils determines the ratio

of the voltages...

...where Vp is the primary (input) voltage, Vs is the secondary (output) voltage, Np is the

number of turns on the primary coil, and Ns is the number of turns on the secondary coil.

Diodes

Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol

shows the direction in which the current can flow. Diodes are the electrical version of a

valve and early diodes were actually called valves.

Figure: Diode Symbol


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A diode is a device which only allows current to flow through it in one direction. In this

direction, the diode is said to be 'forward-biased' and the only effect on the signal is that

there will be a voltage loss of around 0.7V. In the opposite direction, the diode is said to

be 'reverse-biased' and no current will flow through it.

Rectifier

The purpose of a rectifier is to convert an AC waveform into a DC waveform (OR)

Rectifier converts AC current or voltages into DC current or voltage. There are two

different rectification circuits, known as 'half-wave' and 'full-wave' rectifiers. Both use

components called diodes to convert AC into DC.

The Half-wave Rectifier

The half-wave rectifier is the simplest type of rectifier since it only uses one diode, as

shown in figure.

Figure: Half Wave Rectifier

Figure 2 shows the AC input waveform to this circuit and the resulting output. As you

can see, when the AC input is positive, the diode is forward-biased and lets the current

through. When the AC input is negative, the diode is reverse-biased and the diode does

not let any current through, meaning the output is 0V. Because there is a 0.7V voltage

loss across the diode, the peak output voltage will be 0.7V less than Vs.


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Figure: Half-Wave Rectification

While the output of the half-wave rectifier is DC (it is all positive), it would not be

suitable as a power supply for a circuit. Firstly, the output voltage continually varies

between 0V and Vs-0.7V, and secondly, for half the time there is no output at all.

The Full-wave Rectifier

The circuit in figure 3 addresses the second of these problems since at no time is the

output voltage 0V. This time four diodes are arranged so that both the positive and

negative parts of the AC waveform are converted to DC. The resulting waveform is

shown in figure 4.


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Figure: Full-Wave Rectifier

Figure: Full-Wave Rectification

When the AC input is positive, diodes A and B are forward-biased, while diodes C and D

are reverse-biased. When the AC input is negative, the opposite is true - diodes C and D

are forward-biased, while diodes A and B are reverse-biased.

While the full-wave rectifier is an improvement on the half-wave rectifier, its output still

isn't suitable as a power supply for most circuits since the output voltage still varies

between 0V and Vs-1.4V. So, if you put 12V AC in, you will 10.6V DC out.

Capacitor Filter

The capacitor-input filter, also called "Pi" filter due to its shape that looks like the

Greek letter pi, is a type of electronic filter. Filter circuits are used to remove unwanted or

undesired frequencies from a signal.


http://en.wikipedia.org/wiki/Electronic_filter

http://en.wikipedia.org/wiki/Pi_(letter)

http://en.wikipedia.org/wiki/Greek_alphabet

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Figure: Capacitor Filter

A typical capacitor input filter consists of a filter capacitor C1, connected across the

rectifier output, an inductor L, in series and another filter capacitor connected across the

load.

1. The capacitor C1 offers low reactance to the AC component of the rectifier output

while it offers infinite reactance to the DC component. As a result the capacitor

shunts an appreciable amount of the AC component while the DC component

continues its journey to the inductor L

2. The inductor L offers high reactance to the AC component but it offers almost

zero reactance to the DC component. As a result the DC component flows through

the inductor while the AC component is blocked.

3. The capacitor C2 bypasses the AC component which the inductor had failed to

block. As a result only the DC component appears across the load RL.

Figure: Centered Tapped Full-Wave Rectifier with a Capacitor Filter


http://en.wikipedia.org/wiki/Capacitor

http://en.wikipedia.org/wiki/Inductor

http://en.wikipedia.org/wiki/Shunts

http://en.wikipedia.org/wiki/Reactance_(electronics)


http://en.wikipedia.org/wiki/Inductor


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Voltage Regulator

A voltage regulator is an electrical regulator designed to automatically maintain a

constant voltage level. It may use an electromechanical mechanism, or passive or active

electronic components. Depending on the design, it may be used to regulate one or more

AC or DC voltages. There are two types of regulator are they.

Positive Voltage Series (78xx) and

Negative Voltage Series (79xx)

78xx:

’78’ indicate the positive series and ‘xx’indicates the voltage rating. Suppose 7805

produces the maximum 5V.’05’indicates the regulator output is 5V.

79xx:

’78’ indicate the negative series and ‘xx’indicates the voltage rating. Suppose 7905

produces the maximum -5V.’05’indicates the regulator output is -5V.

These regulators consists the three pins there are

Pin1: It is used for input pin.

Pin2: This is ground pin for regulator

Pin3: It is used for output pin. Through this pin we get the output.

Figure: Regulator


http://en.wikipedia.org/wiki/Direct_current

http://en.wikipedia.org/wiki/Alternating_current

http://en.wikipedia.org/wiki/Mechanism_(technology)

http://en.wikipedia.org/wiki/Voltage

http://en.wikipedia.org/wiki/Regulator_(automatic_control)

http://en.wikipedia.org/wiki/Electricity

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MELODY GENERATOR (UM66)


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UM66T is a melody integrated circuit. It is designed for use in bells, telephones, toys etc. It has an inbuilt

tone and a beat generator. The tone generator is a programmed divider which produces certain frequencies.

These frequencies are a factor of the oscillator frequency. The beat generator is also a programmed divider

which contains 15 available beats. Four beats of these can be selected.

There is an inbuilt oscillator circuit that serves as a time base for beat and tone generator. It has a 62 notes

ROM to play music. A set of 4 bits controls the scale code while 2 bits control the rhythm code. When

power is turned on, the melody generator is reset and melody begins from the first note. The speaker can be

driven by an external npn transistor connected to the output of UM66.

Many versions of UM66T are available which generate tone of different songs. For example, UM66T01

generates tone for songs ‘Jingle bells’, ‘Santa Claus is coming to town’ and ‘We wish you a merry X’mas’.


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Pin Description: Pin No Function Name

1 Melody output Output2 Supply voltage (1.5V - 4.5V) Vcc3 Ground (0V) Ground

FEATURES*64-Note Rom memory

*1.5V~4,5V power supply and low power consumption

*Dynamic speaker can be driven with external NPN transistor

*OSC resistor hold mode

*Power on reset: melody begins from the first note

*Built in level hold mode

IR Transmitter, Receiver


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IR SECTION:

WHAT IS INFRARED?

Infrared is a energy radiation with a frequency below our eyes sensitivity, so we cannot

see it

Even that we can not "see" sound frequencies, we know that it exist, we can listen them.

Even that we can not see or hear infrared, we can feel it at our skin temperature sensors.

When you approach your hand to fire or warm element, you will "feel" the heat, but you

can't see it. You can see the fire because it emits other types of radiation, visible to your

eyes, but it also emits lots of infrared that you can only feel in your skin.

INFRARED IN ELECTRONICS

Infra-Red is interesting, because it is easily generated and doesn't suffer electromagnetic

interference, so it is nicely used to communication and control, but it is not perfect, some

other light emissions could contains infrared as well, and that can interfere in this

communication. The sun is an example, since it emits a wide spectrum or radiation.

The adventure of using lots of infra-red in TV/VCR remote controls and other

applications, brought infra-red diodes (emitter and receivers) at very low cost at the

market.

From now on you should think as infrared as just a "red" light. This light can means

something to the receiver, the "on or off" radiation can transmit different meanings.Lots

of things can generate infrared, anything that radiate heat do it, including out body,

lamps, stove, oven, friction your hands together, even the hot water at the faucet.


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To allow a good communication using infra-red, and avoid those "fake" signals, it is

imperative to use a "key" that can tell the receiver what is the real data transmitted and

what is fake. As an analogy, looking eye naked to the night sky you can see hundreds of

stars, but you can spot easily a far away airplane just by its flashing strobe light. That

strobe light is the "key", the "coding" element that alerts us.

Similar to the airplane at the night sky, our TV room may have hundreds of tinny IR

sources, our body and the lamps around, even the hot cup of tea. A way to avoid all those

other sources, is generating a key, like the flashing airplane. So, remote controls use to

pulsate its infrared in a certain frequency. The IR receiver module at the TV, VCR or

stereo "tunes" to this certain frequency and ignores all other IR received. The best

frequency for the job is between 30 and 60 KHz, the most used is around 36 KHz

IR GENERATION

To generate a 36 KHz pulsating infrared is quite easy, more difficult is to receive and

identify this frequency. This is why some companies produce infrared receives, that

contains the filters, decoding circuits and the output shaper, that delivers a square wave,

meaning the existence or not of the 36kHz incoming pulsating infrared.

It means that those 3 dollars small units, have an output pin that goes high (+5V)

when there is a pulsating 36kHz infrared in front of it, and zero volts when there is not

this radiation.


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A square wave of approximately 27uS (microseconds) injected at the base of a transistor,

can drive an infrared LED to transmit this pulsating light wave. Upon its presence, the

commercial receiver will switch its output to high level (+5V).If you can turn on and off

this frequency at the transmitter, your receiver's output will indicate when the transmitter

is on or off.

Those IR demodulators have inverted logic at its output, when a burst of IR is sensed it

drives its output to low level, meaning logic level = 1.

The TV, VCR, and Audio equipment manufacturers for long use infra-red at their remote

controls. To avoid a Philips remote control to change channels in a Panasonic TV, they

use different codification at the infrared, even that all of them use basically the same

transmitted frequency, from 36 to 50 KHz. So, all of them use a different combination of

bits or how to code the transmitted data to avoid interference.

RC-5

Various remote control systems are used in electronic equipment today. The RC5

control protocol is one of the most popular and is widely used to control numerous home

appliances, entertainment systems and some industrial applications including utility

consumption remote meter reading, contact-less apparatus control, telemetry data

transmission, and car security systems. Philips originally invented this protocol and

virtually all Philips’ remotes use this protocol. Following is a description of the RC5.

When the user pushes a button on the hand-held remote, the device is activated and sends

modulated infrared light to transmit the command. The remote separates command data


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into packets. Each data packet consists of a 14-bit data word, which is repeated if the user

continues to push the remote button. The data packet structure is as follows:

2 start bits,

1 control bit,

5 address bits,

6 command bits.

The start bits are always logic ‘1’ and intended to calibrate the optical receiver automatic

gain control loop. Next, is the control bit. This bit is inverted each time the user releases

the remote button and is intended to differentiate situations when the user continues to

hold the same button or presses it again. The next 5 bits are the address bits and select the

destination device. A number of devices can use RC5 at the same time. To exclude

possible interference, each must use a different address. The 6 command bits describe the

actual command. As a result, a RC5 transmitter can send the 2048 unique commands.

The transmitter shifts the data word, applies Manchester encoding and passes the created

one-bit sequence to a control carrier frequency signal amplitude modulator. The

amplitude modulated carrier signal is sent to the optical transmitter, which radiates the

infrared light. In RC5 systems the carrier frequency has been set to 36 kHz. Figure below

displays the RC5 protocol.

The receiver performs the reverse function. The photo detector converts optical

transmission into electric signals, filters it and executes amplitude demodulation. The

receiver output bit stream can be used to decode the RC5 data word. This operation is

done by the microprocessor typically, but complete hardware implementations are

present on the market as well. Single-die optical receivers are being mass produced by a

number of companies such as Siemens, Temic, Sharp, Xiamen Hualian, Japanese Electric

and others. Please note that the receiver output is inverted (log. 1 corresponds to

illumination absence).


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IR TRANSMITTER:

The IR LED emitting infrared light is put on in the transmitting unit. To generate

IR signal, 555 IC based astable multivibrator is used. Infrared LED is driven through

transistor BC 548.

IC 555 is used to construct an astable multivibrator which has two quasi-stable

states. It generates a square wave of frequency 38 kHz and amplitude 5Volts. It is

required to switch ‘ON’ the IR LED. The IR transmitter circuit is as shown below:

555 TIMER:

The 555 is an integrated circuit (chip) implementing a variety of timer and

multivibrator applications. It was designed in 1970 and introduced in 1971 by Signetics

(later acquired by Philips). The original name was the SE555/NE555 and was called

"The IC Time Machine". It is still in wide use, thanks to its ease of use, low price and

good stability. As of 2003, 1 billion units are manufactured every year.


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The 555 timer is one of the most popular and versatile integrated circuits ever

produced. It includes 23 transistors, 2 diodes and 16 resistors on a silicon chip installed in

an 8-pin mini dual-in-line package (DIP-8). The 556 is a 14-pin DIP that combines two

555s on a single chip.

Fig: 555 timer

Pin Functions - 8 pin package

Ground (Pin 1)

This pin is connected directly to ground.

Trigger (Pin 2)

This pin is the input to the lower comparator and is used to set the latch, which in turn

causes the output to go high.

Output (Pin 3)

Output high is about 1.7V less than supply. Output high is capable of sourcing up to

200mA while output low is capable of sinking up to 200mA.


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Reset (Pin 4)

This is used to reset the latch and return the output to a low state. The reset is an

overriding function. When not used connect to V+.

Control (Pin 5)

Allows access to the 2/3V+ voltage divider point when the 555 timer is used in voltage

control mode. When not used connect to ground through a 0.01 uF capacitor.

Threshold (Pin 6)

This is an input to the upper comparator.

Discharge (Pin 7)

This is the open collector to Q14.

V+ (Pin 8)

This connects to Vcc and the Philips data book states the ICM7555 CMOS version

operates 3V - 16V DC while the NE555 version is 3V - 16V DC.

The 555 has three operating modes:

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

include timers, missing pulse detection, bounce free switches, touch switches,

Frequency Divider, Capacitance Measurement, Pulse Width Modulation (PWM)

etc

Astable mode: 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, etc.

Bistable mode: 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, etc.


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How to generate frequency with astable multi based on 555 timer?

This circuit diagram shows how a 555 timer IC is configured to function as an

astable multivibrator. An astable multivibrator is a timing circuit whose 'low' and

'high' states are both unstable. As such, the output of an astable multivibrator toggles

between 'low' and 'high' continuously, in effect generating a train of pulses. This

circuit is therefore also known as a 'pulse generator' circuit.

In this circuit, capacitor C1 charges through R1 and R2, eventually building up

enough voltage to trigger an internal comparator to toggle the output flip-flop. Once

toggled, the flip-flop discharges C1 through R2 into pin 7, which is the discharge pin.

When C1's voltage becomes low enough, another internal comparator is triggered to

toggle the output flip-flop. This once again allows C1 to charge up through R1 and R2

and the cycle starts all over again.

C1's charge-up time t1 is given by: t1 = 0.693(R1+R2) C1. C1's discharge time

t2 is given by: t2 = 0.693(R2) C1. Thus, the total period of one cycle is t1+t2 = 0.693

C1 (R1+2R2). The frequency f of the output wave is the reciprocal of this period, and

is therefore given by:

f = 1.44/ (C1 (R1+2R2))

where f is in Hz if R1 and R2 are in megaohms and C1 is in microfarads.


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IR RECEIVER

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.


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Features

Photo detector and preamplifier in one package

Internal filter for PCM frequency

Improved shielding against electrical field disturbance

TTL and CMOS compatibility

Output active low

Low power consumption

High immunity against ambient light

Continuous data transmission possible (up to 2400 bps)

Suitable burst length .10 cycles/burst


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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 bandpass filter, 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 fulfil the following condition:

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

• 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 necessary.

• 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, RC5 Code, RC6 Code, R–2000 Code and Sony Format (SIRCS). 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 38 kHz or at any other frequency

• Signals from fluorescent lamps with electronic ballast (an example of the signal

modulation is in the figure below).


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IR Emitter and IR phototransistor:An infrared emitter is an LED made from gallium arsenide, which emits near-

infrared energy at about 880nm. The infrared phototransistor acts as a transistor with the

base voltage determined by the amount of light hitting the transistor. Hence it acts as a

variable current source. Greater amount of IR light cause greater currents to flow through

the collector-emitter leads. As shown in the diagram below, the phototransistor is wired

in a similar configuration to the voltage divider.

The variable current traveling through the resistor causes a voltage drop in the pull-up

resistor. This voltage is measured as the output of the device


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Photo

IR reflectance sensors contain a matched infrared transmitter and infrared receiver pair.

These devices work by measuring the amount of light that is reflected into the receiver.

Because the receiver also responds to ambient light, the device works best when well

shielded from abient light, and when the distance between the sensor and the reflective

surface is small(less than 5mm).

IR reflectance sensors are often used to detect white and black surfaces. White surfaces

generally reflect well, while black surfaces reflect poorly. One of such applications is the

line follower of a robot.


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Schematic Diagram for a Single Pair of Infrared Transmitter and Receiver

Theory of

Sensor

Circuit

To get a good voltage

swing , the value of R1

must be carefully

chosen. If Rsensor = a when no light falls on it and Rsensor = b when light falls on it.

The difference in the two potentials is:

Vcc * { a/(a+R1) - b/(b+R1) }

Relative voltage swing = Actual Voltage Swing / Vcc

= Vcc * { a/(a+R1) - b/(b+R1) } / Vcc

= a/(a+R1) - b/(b+R1)

The resistance of the sensor decreases when IR light falls on it. A good sensor will have

near zero resistance in presence of light and a very large resistance in absence of light.

We have used this property of the sensor to form a potential divider. The potential at

point ‘2’ is Rsensor / (Rsensor + R1). Again, a good sensor circuit should give maximum


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change in potential at point ‘2’ for no-light and bright-light conditions. This is especially

important if you plan to use an ADC in place of the comparator

To get a good voltage swing , the value of R1 must be carefully chosen. If Rsensor = a

when no light falls on it and Rsensor = b when light falls on it. The difference in the two

potentials is:

Vcc * { a/(a+R1) - b/(b+R1) }

Relative voltage swing = Actual Voltage Swing / Vcc

= Vcc * { a/(a+R1) - b/(b+R1) } / Vcc

= a/(a+R1) - b/(b+R1)

If

the

emitter and detector (aka phototransistor) are not blocked, then the output on pin 2 of the

74LS14 will be high (apx. 5 Volts). When they are blocked, then the output will be low


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(apx. 0 Volts). The 74LS14 is a Schmitt triggered hex inverter. A Schmitt trigger is a

signal conditioner. It ensures that above a threshold value, we will always get "clean"

HIGH and LOW signals. Not Blocked Case: Pin 2 High Current from Vcc flows through

the detector. The current continues to flow through the base of Q2. Current from Vcc also

flows through R2, and Q2's Drain and Emitter to ground. As a result of this current path,

there will be no current flowing through Q1's base. The signal at U1's pin 1 will be low,

and so pin 2 will be high. Blocked Case: Pin 2 Low Current "stops" at the detector.

Q2's base is not turned on. The current is re-routed passing through R2 and into the base

of Q1. This allows current to flow from Q1's detector and exiting out Q1's emitter. Pin 1

is thus high and pin 2 will be low. To detect a line to be followed, we are using two or

more number of photo-reflectors. Its output current that proportional to reflection rate of

the floor is converted to voltage with a resister and tested it if the line is detected or not.

However the threshold voltage cannot be fixed to any level because optical current by

ambient light is added to the output current.

Most photo-detecting modules are using moderated light to avoid interference by the

ambient light. The detected signal is filtered with a band pass filter and disused signals

are filtered out. Therefore only the moderated signal from the light emitter can be

detected.

Of course the detector must not be saturated by ambient light, this is effective when the

detector is working in linear region.


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The line position is compared to the center value to be tracked, the position error is

processed with Proportional/Integral/Diffence filters to generate steering command. The

line following robot tracks the line in PID control that the most popular algorithm for

servo control.

The proportional term is the common process in the servo system. It is only a gain

amplifier without time dependent process.

The differential term is applied in order to improve the response to disturbance, and it

also compensate phase lag at the controlled object.

The D term will be required in most case to stabilize tracking motion. The I term that

boosts DC gain is applied in order to remove left offset error, however, it often decrease

servo stability due to its phase lag.

When any line sensing error has occurred for a time due to getting out of line or end of

line, the motors are stopped and the microcontroller enters sleep state of zero power

consumption.


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TRANSISTOR DRIVER CIRCUIT:

An SPDT relay consists of five pins, two for the magnetic coil, one as the common

terminal and the last pins as normally connected pin and normally closed pin. When the

current flows through this coil, the coil gets energized. Initially when the coil is not

energized, there will be a connection between the common terminal and normally closed

pin. But when the coil is energized, this connection breaks and a new connection between

the common terminal and normally open pin will be established. Thus when there is an

input from the microcontroller to the relay, the relay will be switched on. Thus when the

relay is on, it can drive the loads connected between the common terminal and normally

open pin. Therefore, the relay takes 5V from the microcontroller and drives the loads

which consume high currents. Thus the relay acts as an isolation device.

Digital systems and microcontroller pins lack sufficient current to drive the circuits like

relays and buzzer which consume high powers. While the relay’s coil needs around

10milli amps to be energized, the microcontroller’s pin can provide a maximum of 1-

2milli amps current. For this reason, a driver such as a power transistor is placed in

between the microcontroller and the relay.


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The operation of this circuit is as follows:

The input to the base of the transistor is applied .The transistor will be switched on when

the base to emitter voltage is greater than 0.7V (cut-in voltage). Thus when the voltage

applied to the (>0.7V), the transistor will be switched on and thus the relay will be ON

and the load will be operated.

When the voltage at (<0.7V) the transistor will be in off state and the relay will be OFF.

Thus the transistor acts like a current driver to operate the relay accordingly.


Vcc

RELAY

GROUND

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BuzzerA buzzer or beeper is an audio signaling device, which may be mechanical,

electromechanical, or electronic. Typical uses of buzzers and beepers include alarms,

timers and confirmation of user input such as a mouse click or keystroke. Early devices

were based on an electromechanical system identical to an electric bell without the metal

gong. Similarly, a relay may be connected to interrupt its own actuating current, causing

the contacts to buzz. Often these units were anchored to a wall or ceiling to use it as a

sounding board. The word "buzzer" comes from the rasping noise that electromechanical

buzzers made.


http://en.wikipedia.org/wiki/Switch

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Relay

http://en.wikipedia.org/wiki/Electric_bell

http://en.wikipedia.org/wiki/Timer

http://en.wikipedia.org/wiki/Alarm

http://en.wikipedia.org/wiki/Electronics

http://en.wikipedia.org/wiki/Electromechanics

http://en.wikipedia.org/wiki/Machine

http://en.wikipedia.org/wiki/Sound

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60db siren

A siren is a loud noise maker. Most modern ones are civil defense or air- raid sirens,

tornado sirens, or the sirens on emergency service vehicles such as ambulances, police

cars and fire trucks. There are two general types, pneumatic and electronic.

Many fire sirens serve double duty as tornado or civil defense sirens, alerting an

entire community of impending danger. Most fire sirens are either mounted on the roof of

a fire station, or on a pole next to the fire station. Fire sirens can also be mounted near

government buildings, on top of tall structures such as water towers, as well as in

systems, where several sirens are distributed around a town for better sound coverage.

Most fire sirens are single tone and mechanically driven by electric motors with a rotor

attached to the shaft.

Some newer sirens are electronically driven by speakers, though these are not as

common. Fire sirens are often called "fire whistles", "fire alarms", "fire horns." Although

there is no standard signaling of fire sirens, some utilize codes to inform firefighters to

the location of the fire. Civil defense sirens pulling double duty as a fire siren often can

produce an alternating "hi-lo" signal (similar to a British police car) as the fire signal, or a

slow wail (typically 3x) as to not confuse the public with the standard civil defense

signals of alert (steady tone) and attack (fast wavering tone).


http://en.wikipedia.org/wiki/Electronics

http://en.wikipedia.org/wiki/Electric_motors

http://en.wikipedia.org/wiki/Water_tower

http://en.wikipedia.org/wiki/Government

http://en.wikipedia.org/wiki/Risk

http://en.wikipedia.org/wiki/Civil_defense

http://en.wikipedia.org/wiki/Tornado

http://en.wikipedia.org/wiki/Fire_apparatus

http://en.wikipedia.org/wiki/Police_car

http://en.wikipedia.org/wiki/Police_car

http://en.wikipedia.org/wiki/Ambulance

http://en.wikipedia.org/wiki/Emergency_service

http://en.wikipedia.org/wiki/Civil_defense_siren

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Electronic sirens incorporate circuits such as oscillators, modulators, and

amplifiers to synthesize a selected siren tone (wail, yelp, pierce/priority/phaser, hi-lo,

scan, airhorn, manual, and a few more) which is played through external speakers. It is

not unusual, especially in the case of modern fire engines, to see an emergency vehicle

equipped with both types of sirens. Often, police sirens also use the interval of a tritone to

help draw attention.


http://en.wikipedia.org/wiki/Amplifier

http://en.wikipedia.org/wiki/Modulation

http://en.wikipedia.org/wiki/Oscillator

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Advantages:

Highly sensitive

Two stage Gain control

Very low noise

Low cost and reliable circuit

Can transmit up to 10 meter


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Applications:

Wireless Speaker System

Welcome Tone generators at entrance


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Conclusion

The project “Wireless Music transmission and reception by IR communication

” is designed, tested and implemented successfully. It is much easy and cost effective.


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REFERENCES:

Text Books:

Website:

www.howstuffworks.com

www.answers.com

www.WineYard.in

Magazines:

Electronics for you

Electrikindia

Go Wireless


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