Minor Project On Fm Wireless

               

   

 

MINOR PROJECT ON FREQUENCY MODULATED WIRELESS MICROPHONE GUIDED BY:-

SUBMITTED BY:-

MAYANK MITTAL

PRATIK SADIWALA PRATIKSH SINGH

               

   

 

MINOR PROJECT ON RADIO REMOTE CONTROL USING DTMF GUIDED BY:-

SUBMITTED BY:-

MAYANK MITTAL

PALLAVEE ANKITA SOLANKI

                    

INTRODUCTION A wireless microphone, as the name implies, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Reg Moores developed a radio microphone that was first used in "Alladin on Ice" in 1949. John F. Stephens developed an FM wireless microphone for a Navy musical show in 1951 on the Memphis Naval base Modern wireless microphone technology, which for the first time offered performance with audio and dynamic range equivalent to a cord, originated with the introduction of the first compander wireless microphone offered by Nady Systems, Inc in 1976 according to company claims. Nady systems, Inc was honored with an Emmy award for this breakthrough technical achievement in 1996. More commonly known as a Radio Microphone, there are many different standards, frequencies and transmission technologies used to replace the microphone's cable connection and make it into a wireless microphone. They can transmit, for example, in radio waves using UHF or VHF frequencies, FM, AM, or various digital modulation schemes. Some low cost models use infrared light. Infrared microphones require a direct line of sight between the microphone and the receiver, while costlier radio frequency models do not. Some models operate on a single fixed frequency, but the more advanced models operate on a user selectable frequency to avoid interference, and allow the use of several microphones at the same time. This simple FM wireless microphone transmitter can transmit speech over a short range. It can be used as a simple cordless microphone. The circuit uses two integrated circuits from Maxim. IC1 a MAX4467, is an amplifier raising the microphone signal to a level suitable for frequency modulation (FM). IC2 is a voltage-controlled oscillator (VCO) with integrated varactor (a.k.a. varicap diode).

     

WORKING Its nominal frequency of oscillation is set by inductor L1. The inductor value 390 nH provides an oscillation frequency of about 100 MHz. For best performance, L1 should be a high-Q component. L1 may consist of 4 turns of silver-plated wire wound around a 10-mm drill bit, and stretched to a length of about 1.5 cm. The wire diameter can be anything between 26 SWG (0.5 mm) and 20 SWG (1 mm). No core is used. The MAX4467 is a micropower opamp for low voltage operation and providing 200-kHz gain bandwidth at a supply current of just 24 μA. When used with an electret microphone, some form of DC bias for the microphone capsule is necessary. The MAX4467 has the ability to turn off the bias to the microphone when the device is in shutdown mode. This can save several hundred microamps of supply current, which can be significant in low power applications particularly for battery powered applications like cordless microphones. The MICBias pin provides a switched version of Vcc to the bias components. Resistor R1 resistor limits the current to the microphone element. The output impedance of the MAX4467 is low and well suited to driving cables over distances up to 50 m. The MAX2606 intermediate-frequency (IF) voltage-controlled oscillators (VCO) has been designed specifically for portable wireless communication systems. The IC comes in a tiny 6-pin SOT23 package. The low-noise VCO features an on-chip varactor and feedback capacitors that eliminate the need for external tuning elements. Only an external inductor (here, L1) is required to set the oscillation frequency and produce a properly operating VCO. To minimize the effects of parasitic elements, which degrade circuit performance, place L1 and C5 close to their respective pins. Specifically, place C5 directly across pins 2 (GND) and 3 (TUNE).

CONSTRUCTION

Wireless microphone circuit schematic

 

COMPONENTS Parts List: R1,R2 = 2K (brown-black-orange) R3,R7 = 20K (brown-black-yellow) R4,R5 = 100 ohm (yellow-violet-brown) R6 = 168K R8 = 47K R9 = 330 ohm R10,R11 = 1K C1 = 100 nF C2 = 4.7uF-16V, electrolytic C3 = 10 uF-10V C4 = 470 nF C5 = 0.001uF (1nF), ceramic C6 = 1 uF-10V, ceramic C7 = 680 pF C8 = 10 uF-10V L1 = 390uH, variable inductor Mic = Electret mike, 2 wires Ic1 = MAX 4467 Ic2 = MAX 2606

APPLICATION Device purpose: This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. The battery supply is a good compromise: in this manner the input circuit is free from mains low frequency hum pick-up and connection to the amplifier is more simple, due to the absence of mains cable and power supply. Using a stereo microphone the circuit must be doubled. In this case, two separate level controls are better than a dual-ganged stereo potentiometer. Low current drawing (about 2mA) ensures a long battery life.

Advantages and disadvantages The advantages are: • • •

Greater freedom of movement for the artist or speaker. Avoidance of cabling problems common with wired microphones, caused by constant moving and stressing the cables. Reduction of cable "trip hazards" in the performance space

The disadvantages are: •

• •

• • •

Sometimes limited range (a wired balanced XLR microphone can run up to 300 ft or 100 meters). Some wireless systems have a shorter range, while more expensive models can exceed that distance. Increased latency at longer distances Possible interference with or, more often, from other radio equipment or other radio microphones, though models with many frequency-synthesized switch-selectable channels are now plentiful and cost effective. Limited operation time due to battery life. Noise or dead spots (places where it doesn't work, especially in non-diversity systems) Limited number of operating microphones at the same time and place, due to the limited number of radio channels (frequencies

BLOCK DIAGRAM

There are four Main components in block diagram of Frequency Modulated wireless Microphone.They are:•

Microphone:-It is a device by which audio signal given is converted into electrical signal & transferred to Transmitter.

•

Transmitter:-It is used to transmit electrical signal provided by Microphone to Transmitting antenna from which the signal is send to receiving antenna.

•

Receiver:-It is used to receive transmitted signal from receiving antenna and convert it from electric signal to audio signal again.

•

Sound system or radio:-The converted audio signal is transferred to a Sound System or radio so that the transmitted audio signal can be easily listened on it.

BIBLIOGRAPHY 1. 2. 3. 4. 5. 6.    

wireless microphone system: Revolabs. www.electroschematics.com www.electronicslab.com www.flashwebhost.com www.electronics4u.com www.redcircuit.com

CONTENTS 1.Introduction 2.Block diagram 3.Construction 4.Components 5.Working 6.Application 7.Bibliography