Design and Construction of a Function Generator


In this work a multi-wave form function generator was designed and built. It gave perfect sinewave, triangular and square wave forms. The operating frequency ranges from 70.5Hz to  327.3KHz. The production is modular in nature with discrete components forming each module. This approach was adopted to aid troubleshooting, maintenance and repair. To make the module neat, all circuits were etched on a printed circuit (PC) board and coupled in such a way as to reduce signal distortion and noise in the circuit. The final product was tested and experimental results agree with the design values. The function generator can find usage in electronic laboratories and workshops as signal generator, testing and measuring instruments. For economic considerations, all components were sourced locally.



1.1     Background of the project Work

          The technological progress of any nation depends on its ability to measure, calculate and finally estimate the unknown. And also the success of any engineer or technologist is judged by his ability to measure and test precisely and to accurately interpret the circuit performance.

          In electronic laboratories, we have many equipment. Some are testers and some are measuring instrument while some are both testing and measuring instruments. There are also generators, and generators generate either dc or ac signals. A power supply can generate both direct current (dc) and alternating current (ac), but the alternating current is only a sinusoidal waveform such as that generated through audio. Signals can also be generated using equipment, and that is signal or function generator.

A function generator is a signal source that has the capability of producing different types of waveforms as its output. The most common waveforms are sine wave, triangular wave, square wave and sawtooth wave. (Balashi, 2008). The frequencies of such waves may be adjusted from fractions of a hertz to several hundreds of kilo hertz. They are very versatile instrument as they are capable of producing a wide variety of waveforms and frequencies that are particularly suitable for different types of applications in electronics experiments.

          Function generators serve as signal generators, measurement and testing instruments in any standard electronic laboratory. The waveforms generated are used in the development, testing and repair of other electronic equipment. For example, they may be used as a source to test amplifiers or to introduce an error signal into control loop.

1.2     Statement of Problems

          The current problems associated with imported function generators being used in our electronic laboratories are that

  • The function generators brake down easily due to harsh weather (heat and dust) in our Laboratories.
  • These instruments lack trained personnel to maintain and repair them and as such too many of them are out of use (redondant).
  • In some cases, where these equipment has some technical personnel who can repair them do not see their spare (components) parts in our local markets.
  • High exchange rate of foreign currency make the instruments very costly and as such few are purchased, and these few do not meet up the demand in our electronic laboratories.
  • In most cases, the suppliers are not experts who know these equipment very well, therefore some equipment may come without their working and maintenance manuals or come with incomplete parts, and as such will not be used.

With the above problems, locally designed function generator  with discrete components will be the solution to them all.

1.3     Research Objective

          This design is aimed at developing and implementing a function generator that will solve problems of too many redundant instrument in our electronic laboratories by using discrete components.

  • It provide solution to lack of spare parts (components) which makes repair impossible.
  • Using discrete components makes the production cheaper or less costly than importing them.
  • The locally designed will be easy to maintain and repair.

1.4     The Scope and Limitation

  • The scope of the project is capable of giving out three types of output wave forms square wave, triangular wave and sine wave.
  • This project gives a frequency that is not below 70Hz.
  • This design cannot give frequencies higher than 350 kilohertz. It cannot give more than three output wave forms.

1.5     Significance of the Project

          The important of this design is to have functionable function generators in our electronic laboratories.

          To have enough of the function generator to meet our greater number of students by so doing enable, not all the students participate in practical work.

          The importance of this design is to have an easy to maintain repair, and cheap to produce.

1.6     Report Organisation

          This project is organized into five main chapters. The first chapter discuses the background of this project, problem associated with previous types in the market, aims and objectives of embarking on this design. In the second chapter, the detail theory of the major units and their working principles were explained and also the review of other works done by others. The chapter three gives the method that was used, the block diagram and flow chat of the project was used to explain the function of the project. The main design which improve the calculations in different block diagram were given in this chapter. The method used in choosing the components is also contend in this chapter. The chapter four gives the construction and testing of the project, the result is also given in this chapter. All the circuit diagrams of the design is shown in this chapter. The chapter five gives the conclusion and recommendation of the project.




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