IR music tx and rx

Category: Education

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Now-a-days everything in this world is getting wireless. Infrared rays’ transmission is one of the most important ways of wireless communication. According to the infrared communication, for a distance of about 1 m from a communication object the communication can be performed without performing connection via a cable, and the like, which is convenient for use, and which provides an advantage that the communication can be realized with a simple constitution as compared with the communication using radio waves. From such advantage, the infrared communication is preferably applied to small apparatuses such as a note type personal computer and a portable information terminal. INFRARED COMMUNICATION

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INTRODUCTION Using this circuit, audio musical notes can be generated and can be heard up to a distance of 10 meters. The receiver can be placed at a maximum distance of 1 meter from the transmitter without any considerable noise interference. However the communication distance can be improved by using Far IR LEDs. The range of communication can be increased to about 250 meters by using Far IR LEDs. This project emphasizes the way by which music is generated and driven by IR rays and gives an explanation to the one of the methods of receiving IR rays without considerable noise interference.

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TRANSMITTER CIRCUIT The IR music transmitter works off a 9V battery, . This figure shows the circuit of the IR music transmitter. It uses popular melody generator IC UM-66 (IC1) that can continuously generate musical tones. The output of IC1 is fed to the IR driver stage (built across the transistors T1 and T2) to get the maximum range. Here the red LED (LED1) flickers according to the musical tones generated by UM66 IC, indicating modulation. IR LED2 and LED3 are infrared transmitting LEDs. For maximum sound transmission these should be oriented towards IR phototransistorL14F1 (T3).

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RECEIVER CIRCUIT The IR music receiver uses popular op-amp IC µA741 and audio-frequency amplifier IC LM386 along with phototransistor L14F1 and some discrete components (Fig. 2). The melody generated by IC UM66 is transmitted through IR LEDs, received by phototransistor T3 and fed to pin 2 of IC µA741 (IC2). Its gain can be varied using pot meter VR1. The output of IC µA741 is fed to IC LM386 (IC3) via capacitor C5 and pot meter VR2.The melody produced is heard through the receiver’s loudspeaker. Pot meter VR2 is used to control the volume of loudspeaker LS1 (8-ohm, 1W).

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Basic Electronic Components All components used in electronic circuits have three basic properties, known as resistance, capacitance, and inductance. In most cases, however, one of these properties will be far more prevalent than the other two. Therefore we can treat components as having only one of these three properties and exhibiting the appropriate behavior according to the following definitions: Resistance: The property of a component to oppose the flow of electrical current through itself.  Capacitance: The property of a component to oppose any change in voltage across its terminals, by storing and releasing energy in an internal electric field.  Inductance: The property of a component to oppose any change in current through itself, by storing and releasing energy in a magnetic field surrounding itself.

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In electronics, a diode is a two-terminal device (thermionic diodes may also have one or two ancillary terminals for a heater). Diodes have two active electrodes between which the signal of interest may flow, and most are used for their unidirectional electric current property. The vari-cap diode is used as an electrically adjustable capacitor. The directionality of current flow most diodes exhibit is sometimes generically called the rectifying property. The most common function of a diode is to allow an electric current to pass in one direction (called the forward biased condition) and to block the current in the opposite direction (the reverse biased condition). Thus, the diode can be thought of as an electronic version of a check valve. DIODE :

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LED A light-emitting-diode (LED) is a semiconductor diode that emits light when an electric current is applied in the forward direction of the device, as in the simple LED circuit. The effect is a form of electroluminescence where incoherent and narrow-spectrum light is emitted from the p-n junction in a solid state material. LEDs are widely used as indicator lights on electronic devices and increasingly in higher power applications such as flashlights and area lighting. An LED is usually a small area (less than 1 mm2) light source, often with optics added directly on top of the chip to shape its radiation pattern and assist in reflection. The color of the emitted light depends on the composition and condition of the semi conducting material used, and can be infrared, visible , or ultraviolet.

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PHOTO DIODE A photodiode is a type of photo detector capable of converting light into either current or voltage, depending upon the mode of operation. Photodiodes are similar to regular semiconductor diodes except that they may be either exposed (to detect vacuum UV or X-rays) or packaged with a window or optical fibre connection to allow light to reach the sensitive part of the device. Many diodes designed for use specifically as a photodiode will also use a PIN junction rather than the typical PN junction.

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INFRARED EMITTER AND DETECTOR 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. the phototransistor is wired in a similar configuration to the voltage divider. The variable current travelling 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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IC UM 66 MUSIC GENERATOR PIN 1 OUTPUT PIN 2 +Vcc PIN 3 -Vcc This is the simplest ever musical calling bell that can be easily built. It uses the musical 3 pin IC UM66 and a popularly known Transistor BC548b. Here the musical IC UM66 generates the music when it receives supply and drives a small speaker through a class c amplifier using silicon transistor BC548b.

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IC UM 66 cont. The battery supply should be kept in a battery container to ensure the connection. The volume of the sound of this circuit is so much that it can be used as a calling bell. If anyone want to reduce the volume of the circuit then insert a resistance () in place of the blue line connection. In this circuit please don't give the supply beyond 3 volt without modification as the IC may got damaged. The circuit should not be run in Rechargeable battery also if the Speaker resistance is less than 8 Ohm and may burn the Transistor.

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PRECAUTION POINTS OF IMPORTANCE FOR IC UM 66 Never connect the IC in reverse supply connection. The music depends on the part number of the IC . The transistor are should be connected in proper pin configuration. The recommended power supply is battery of 3 volt. The speaker and resistance has no terminal polarity and connection points can be interchanged.

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LOW VOLTAGE AUDIO POWER AMPLIFIER LM 386 The LM386 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200. The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation.

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The LM386 comes in 3 flavors now; LM386-1, LM386-2, LM386-3 with output power levels of 300, 500 and 700 milli-watts respectively. The type sold by Radio Shack is the LM386-1 and is the one we used in this circuit. Perhaps the most unique feature is that it is available at any Radio Shack and can operate at voltages as low as 5 volts. It is important to understand that increasing the gain does not increase the output power. The increased gain is only used when a very low input signal is to be amplified. Our next IC is the LM380 and it also comes in two flavors; LM380-8 and LM380 with output powers of 700 milli-watts and 2 watts respectively. IC LM 386 cont.

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FEATURES AND APPLICATIONS OF IC LM386 FEATURES: Battery operation Minimum external parts Wide supply voltage range: 4V–12V or 5V–18V Low quiescent current drain: 4mA Voltage gains from 20 to 200 Ground referenced input Self-centering output quiescent voltage Low distortion: 0.2% Available in 8 pin MSOP package APPLICATIONS : AM-FM radio amplifiers Portable tape player amplifiers Intercoms TV sound systems Line drivers Ultrasonic drivers Small servo drivers Power converters

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The diagram opposite shows the pins of the 741 OP-AMP. The important pins are 2, 3 and 6 because these represent inverting, non-inverting and voltage out. Notice the triangular diagram that represents an Op-Amp integrated circuit. IC 741 PIN REPRESENTATION

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DYNAMIC LOUDSPEAKER The loudspeakers are almost always the limiting element on the fidelity of a reproduced sound in either home or theater. The other stages in sound reproduction are mostly electronic, and the electronic components are highly developed. The loudspeaker involves electromechanical processes where the amplified audio signal must move a cone or other mechanical device to produce sound like the original sound wave. This process involves many difficulties, and usually is the most imperfect of the steps in sound reproduction. Choose your speakers carefully. Some basic ideas about speaker enclosures might help with perspective.

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TYPES OF ENCLOUSERS The production of a good high-fidelity loudspeaker requires that the speakers be enclosed because of a number of basic properties of loudspeakers. Just putting a single dynamic loudspeaker in a closed box will improve its sound quality dramatically. Modern loudspeaker enclosures typically involve multiple loudspeakers with a crossover network to provide a more nearly uniform frequency response across the audio frequency range. Other techniques such as those used in bass reflex enclosures may be used to extend the useful bass range of the loudspeakers.

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TRANSFORMERS Transformers convert AC electricity from one voltage to another with little loss of power. Step-up transformers increase voltage, step-down transformers reduce voltage. Most power supplies use a step-down transformer to reduce the dangerously high mains voltage (230V in UK) to a safer low voltage. The input coil is called the primary and the output coil is called the secondary. There is no electrical connection between the two coils, instead they are linked by an alternating magnetic field created in the soft-iron core of the transformer. The two lines in the middle of the circuit symbol represent the core.

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VOLTAGE TRANSFORMER Voltage transformers (VTs) or potential transformers (PTs) are another type of instrument transformer, used for metering and protection in high-voltage circuits. They are designed to present negligible load to the supply being measured and to have a precise voltage ratio to accurately step down high voltages so that metering and protective relay equipment can be operated at a lower potential. Typically the secondary of a voltage transformer is rated for 69 or 120 Volts at rated primary voltage, to match the input ratings of protection relays.

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POWER SUPPLY The input to the circuit is applied from the regulated power supply. The a.c. input i.e., 230v from the mains supply is step down by the transformer to 12v and is fed to a rectifier. The output obtained from the rectifier is fed to a filter to remove any a.c components present even after rectification. Now , this voltage is given to a voltage regulator to obtain a pure constant dc voltage.

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POWER SUPPLY IN DETAIL Transformer + Rectifier: The varying DC output is suitable for lamps, heaters and standard motors. It is not suitable for electronic circuits unless they include a smoothing capacitor. Transformer + Rectifier + Smoothing: The smooth DC output has a small ripple. It is suitable for most electronic circuits.

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Transformer + Rectifier + Smoothing + Regulator: The regulated DC output is very smooth with no ripple. It is suitable for all electronic circuits. Dual Supplies: Some electronic circuits require a power supply with positive and negative outputs as well as zero volts (0V). This is called a 'dual supply' because it is like two ordinary supplies connected together as shown in the diagram. Dual supplies have three outputs, for example a ±9V supply has +9V, 0V and -9V outputs.

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APPLICATIONS , ADVANTAGES & DISADVANTAGES APPLICATIONS: Wireless Music Systems. Mobile gadgets. CC cameras ADVANTAGES: Highly sensitive Two stage Gain control Very low noise Low cost and reliable circuit Can transmit up to 10 meter DISADVANTAGES: Not for long distance work in fixed range Noise if object between transmitter and receiver

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CONCLUSION IR ray communication is very easy to understand and simple to implement. It finds various applications in short distance field of communications. It is one of the best ways of building wireless gadgets. In future there is scope of building virtual environment using the principles of IR ray transmission and reception. Virtual gaming which also employs IR reception techniques is still in research process which is soon going to rule the world of gaming.

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