Design And Construction Of A Wireless Microphone

ABSTRACT

This paper presents the design and construction of a wireless microphone FM transmitter with a range of about 100meters. Wireless microphone FM transmitter with a range of about 100meters.  The use of cable microphones creates inconvenience and obstruction while in use so it becomes paramount to design and construct a wireless microphone using Frequency Modulation as link instead of a cable with a reception which should be portable, affordable and operate efficiently. The transmitter works using a 9v dc supply which operates on the principle of FM (frequency modulation) band.

The design consists of four parts which include; the input unit (electric microphone), audio amplifier unit, modulator and finally the oscillator unit. The input unit is a microphone which is used to provide the signal in the form of speech amplified by the audio amplifier; the amplified signal is then transferred to the modulator unit where the signal is being superimposed on the carrier wave in a suitable manner. The oscillating unit which is an LC oscillator provides the necessary high frequency needed for transmitting the signal through an antenna. The output is a signal transmitted through a distance of 100m which is transmitted at a frequency of 102.3MHZ

CHAPTER ONE

• INTRODUCTION

This project work is wireless microphone which can be used for recording and paying back your voice wirelessly.

Cordless or wireless microphone and amplifier units are generally used during public address programs, stage entertainment programs or in all forms of occasions where voice signals are required to be amplified so as to make them audible over a wider area and distance.

However since microphones are normally held by the hand while speaking, the unit needs to be perfectly hassle free so that the individual holding it is able to move about the premise freely. In this article we learn how to construct a simple wireless microphone circuit and use exactly for the above intended purpose.

The main active part of the circuit is the microphone, MAX4467 ic and voltage controlled oscillator (vco), while the other supporting passive parts are also very few making the item very compact as far as part count is concerned.

A microphone converts voice or sound vibrations in the air into electrical pulses. They are generally used for public address purposes and entertainment programs. Here we learn a very simple way of making an FM wireless microphone circuit that requires no wires for the specified operation

Older types of mics carried a wire or an electrical cord from the mic up to the amplifier, making things very cumbersome and inconvenient for the user. The cord used to dangerously dangle about the legs of the user making him vulnerable to entanglement and even stumbling because of the mess.

This led to the invention of much sophisticated wireless types of mics which became much comfortable to handle and use on any platform, moreover the distance of the user from the amplifier also was no longer an issue now. However the invention could take place only after the invention and improvements in the FM broadcast technology, because the wireless mic actually incorporated a small FM transmitter which sent the voice signals in the form of FM waves to the FM receiver before it could get amplified in to the loudspeakers.

These wireless mics are still being used effectively for the intended applications and have become quite indispensable with the specific users.

Though the device may look quite sophisticated with its operations, but did you know it is actually very easy to construct as an electronics engineering student. The full details of this design as discussed in this work.

1.2                                         BACKGROUND OF THE PROJECT

Electronics deals with current flow and the application therefore current is established by movement of electron-hence electronics. Electrons on their own are constituent of the atom. We shall bargain therefore by considering our need for electronics in every day activities because to has become obvious. As the world grow computerized, we ought to have the knowledge and understanding of electronics for certain reason.

As a matter of fact, our satisfaction these days mostly depend on electronics. These satisfactions may come in different ways. For instance one cam now stay in his house or in motor to communicate with distance person through telephones; one can tune radio or television on station inside his house, to mails. Some information can be transmitted by the aid of microphone. All these and more make life easier and less stressful for us.

The study of electronics is not so simple as may be perceived by people who professionalized in its operation.

It deals with the movements of electrons and electromagnetic wave in short everything that happens in electronics is invisible. “Electronics, according to advanced leaner dictionaries” is the science and technology of electronics phenomena, devices and system, as in radio, Television, tape recorder, compute etc.

Considering the project I am writing now, the radio transmitter. Radio transmitter generates energy at a definite frequency and convey this energy to the transmitting aerial for radiation. To obtain a useful radiated signals, information must be superimposed on the radio waves. In the continuous wave (C.W) transmitters used for radio, telegraphy, the desired information is added by interrupting the radio frequency oscillations in accordance with a telegraphic code. In radio telephone (modulated) transmitters the information is added by modulating either the amplitude or the frequency of the radio frequency carrier wave the speech or music to be transmitted.

1.3                                                    AIM AND OBJECTIVES OF THE PROJECT

The main aim of this work is to study the working system of a wireless microphone. At the end of the study, students involved shall be able to know the working principle of a wireless microphone and major components they were made of was also studied.

1.4                                                           SIGNIFICANCE OF THE PROJECT

1. This device provides greater freedom of movement for the user.
2. 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

1. Galvanic isolation of microphone, avoiding ground loops between microphone and other electrical instruments on stage.

1.5                                                             LIMITATION OF THE PROJECT

• 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. 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.
• Operation time is limited relative to battery life; it is shorter than a normal condenser microphone due to greater drain on batteries from transmitting circuitry, and from circuitry giving extra features, if present.
• 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).
• Higher cost in proportion to fewer other features

1.6                                                                   SCOPE OF THE PROJECT

Wireless microphone is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Also known as a radio microphone, it has a small, battery-powered radio transmitter in the microphone body, which transmits the audio signal from the microphone by radio waves to a nearby receiver unit, which recovers the audio. The other audio equipment is connected to the receiver unit by cable. Wireless microphones are widely used in the entertainment industry, television broadcasting, and public speaking to allow public speakers, interviewers, performers, and entertainers to move about freely while using a microphone to amplify their voices.

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 (or specialist) 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.

1.7                                                            APPLICATION OF THE PROJECT

Wireless microphone is used in many different environments. Some of the more popular uses are churches, sporting events, fitness centers, homes, cars, correctional facilities and holiday light shows. Other applications include

• Non-commercial broadcasting.
• Commercial broadcasting.
• Television audio.
• Public Service communications.
• Radio Service Communications.
• Point-to-point microwave links used by telecommunications companies.

1.7                                                                    DEFINITION OF TERMS

FM – Frequency Modulation

VHF – Very High Frequency (30MHz to 300MHz)

UHF – Ultra High Frequency (300MHz to 3GHz)

VFO – Variable Frequency Oscillator

VCO – Voltage Controlled Oscillator

PLL – Phase Locked Loop

Oscillator – device that generates a frequency

1.8                                                     PROJECT OUTLINES

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to this study. In this chapter, the background, significance, scope, objective, application, limitation and problem, definition of terms used in this work were discussed.

Chapter two is on literature review of the study. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.