CALIBRATION AND APPLICATION OF CATHODE RAY OSCILLOSCOPE IN OUR LABORATORY

CALIBRATION AND APPLICATION OF CATHODE RAY OSCILLOSCOPE IN OUR LABORATORY

ABSTRACT

The cathode ray Oscilloscope plays a very important role in the laboratories, for instance it is used to measure frequency and voltage of a signal it is equally used for study current fluctuation in electric power supply the cathode ray oscilloscope is made up of three major part, they are the cathode ray tube, which is the major integral part A the Oscilloscope also the other important[1 parts of the Oscilloscope is the power supply unit and the vertical as well as horizontal amplifier. Some of the cathode ray oscillioscope are calibrated manually while some are already calibrated by the manufacturers.  The subpart of the oscilloscope which include Cathode Ray Tube   (CRT) is made of three (3) major parts namely the electron gun which produces electron before acceleration and the second sub part of the instrument in the deflecting plates which helps to deflect the electron towards the screen where it is seen.  This cathode Ray Oscilloscope works in the principle that the signal to be displayed is amplified by the vertical amplifier and applied to the vertical deflection plates of the CRT, a portion of the signal in the vertical amplifier is applied to the sweep trigger as a triggering signal.  Then the sweep trigger generates a pulse coincident with a selected point in the cycle of the triggering signal.  This pulse turns on the sweep generator. Initiating the saw-tooth wave form.

REFERENCES                                                                       

CHAPTER ONE

1.0  INTRODUCTION

1.1    THE BACKGROUND REVIEW OF THE CATHODE RAY OSCILLIOSCOPE

The cathode Ray oscilloscope (CRO) is an extremely useful and versatile laboratory instrument used for measurement and analysis of wave forms and other phenomenon in electronic acts.  It provides a means of observing time varying voltages, it can present a visual representation of dynamic phenomena by means of transducers that converts current, pressure, strain, temperature, acceleration and many other physical quantities into voltages.

Recording of what is happening in oscilloscope can be made by a special camera attached to the cathode ray oscillioscope (CRO) for quantitative interpretations (keith, 1995).

Paul (2000) stated that cathode- ray oscilloscope (CRO) is a device e which displays a graph of an electrical signal on the face of a cathode ray tube. This is usually done by displaying a time-varying potential (voltage) potential (voltage) on the vertical axis (y), anytime on the horizontal axis. This is called the “y-t” mode. Most oscilloscope also allow the horizontal axis to be driven with another time varying potential.  In this mode, the horizontal axis is called the x- axis, and this is called the x-y mode common with the Cathode Ray Tube (CRT) has much in tube of the TV sets. A hot wire filament heats a metal cathode which then emits electrons. These electrons are accelerated by a high potential (typically 10kv), collimated in to a narrow beam and focused to a small spot on the front of the Cathode Ray Tube (CRT). They give up their energy to the atoms in the phosphor coating on the front of the tube.  These excited atoms quickly give up their energy in the form of light.  Thus, the small spot struck by the election beam give off visible light.  The struck by electron beam give off visible light.  The beams is aimed as a particular spot on the phosphor screen by two pair of electrostatic deflecting plates, one set to deflect the beam up or down and the other to deflect the beam left or right (Bruce D, 1969).

The deflecting plates potential are controlled by the output of two independent electronic amplifier while the horizontal amplifier is driven by saw tooth wave generator (within the Oscillioscope).  The saw tooth generator drives the electron beam horizontally at a constant speed, then quickly returns it to sweep again.  The right-to-left motion is usually so rapid that the eye cannot follow the motion, and only the left to right sweep is seen.  The phosphor coating of the screen has persistence which causes it to glow for a short time after being excited. The persistence of the screen and the persistence of the human eye (vision) combine to produce a flicker free illusion of a continuously traced graph (Paul, 2000).

CALIBRATION AND APPLICATION OF CATHODE RAY OSCILLOSCOPE IN OUR LABORATORY