CATHODE RAY OSCILLOSCOPE (CRO)

THIS ARTICLE CONTAINS BASIC INTRODUCTION OF CRO,BLOCK DIAGRAM OF CRO,CIRCUIT OF CRO,CATHODE RAY TUBE :- BASIC INTRODUCTION OF ELECTRON GUN,ANODE PLATES,DEFLECTING PLATES,SCREEN OF CRO,ADVANTAGES AND DISADVANTAGES OF CRO.

1. CATHODE RAY OSCILLOSCOPE

2. PRESENTED BY- SUSHIL KUMAR SINGH LAKSHMI SIDDHARTH YADAV MRIGANKA BHATTACHARJEE KRISHNA KUMAR BHARGAV ( dedicated to Almighty god ) 2 UNDER THE GUIDENCE OF – UPMA DAS 16 May, 2017

3. CONTENTS- INTRODUCTION BLOCK DIAGRAM OF CRO CALCULATION CATHODE RAY TUBE ADVANTAGES / DISADVANTAGES APPLICATIONS 3 16 May, 2017

4. INTRODUCTION- CRO is an electronic device containing a cathode ray tube(CRT) that generates an electron beam that is used to produce visible patterns, graphs on a phosphorescent screen. HISTORY : The first CRO was developed by German physicist Ferdinand Brawn in 1897. CRO is a common laboratory instrument that provides accurate time and amplitude Measur- ement of voltage signal over a wide range of frequency . 4 16 May, 2017

5. FIG: EXTERNAL VIEW OF CRO 5 16 May, 2017

6. TYPES OF CRO- ANALOG CRO : It is the simplest and earliest type of oscilloscope comprises of a vertical amplifier, a cathode ray tube, time base, a power supply and a horizontal amplifier. These are commonly known as analog CRO. DIGITAL CRO : It is a complex electronic device composed of various software and electronic hardware modules that work together to capture, process, display and store data that represents the signals of interest of operator. 6 16 May, 2017

7. BASIC BLOCKS OF CRO- 7 16 May, 2017

8. BLOCK DISCRIPTION- VERTICAL AMPLIFIER: The input signals are amplified by vertical amplifier to make the waveform compatible for operation. We can obtain the sensitivity of oscilloscope by vertical amplifier. The sensitivity of an oscilloscope (in V/div.) is directly proportional to the gain of the vertical amplifier. TRIGGER CIRCUIT: The signals which are used to activate the trigger circuit are converted to trigger pulses for the precision sweep operation whose amplitude is uniform . Hence input signal can be synchronized . 8 16 May, 2017

9. TIME-BASE GENERATOR: The Time-base circuit uses a Transistor, which is used to produce the ramp voltage . The ramp voltage produced by this circuit is required to deflect the beam in horizontal section. 9 FIG:-Sweep circuit and ramp voltage diaram 16 May, 2017

10. 10 16 May, 2017 HORIZONTAL AMPLIFIER: The ramp voltage produced by the time base generator is amplified by the horizontal amplifier ,before it applied to horizontal deflection plates. Delay Line: The Delay line retards the arrival of the amplified waveform obtained from vertical amplifier to reach to the vertical plates.

11. BASIC CRO CIRCUIT- 11 16 May, 2017

12. 12 16 May, 2017 BLANKING CIRCUIT: While retracing the horizontal line from left to right, the movement of spot will appear as a thin and dim line. Ideally it should be invisible, so to make it invisible a circuit provided known as blanking circuit . CALIBRATION OSCILLATOR: Some laboratory oscilloscopes having internally generated input voltage of known voltage which is provided by this oscillator circuit.

13. CALCULATION FORMULA1 Voltage(V)= ( no.of division) X (*ch1). Peak voltage=2V Where :*ch1 is the VOLTAGE/DEVISION Value Of the waveform. FORMULA2 Time period= ( no.of division) X (TB). Where: TB is the TIME/DEVISION Volt=1*5 =5volt. Time =(.2 ms )*2 =(.4 ms ) frequency=1/(.4ms) =2.5 kHZ 13 16 May, 2017

14. CATHODE RAY TUBE - It consist of THREE major portion- v1 v2 14 16 May, 2017

15. ELECTRON GUN: Electron gun tube is the source of electron which emits electron with very high ENERGY & acceleration / 15 16 May, 2017

16. ANODE PLATES(focusing & accelerating) ++ ++ ++++ ++ --------------------------------------------- ++ ++ ++ ++ Function of Anode plates is to give a ACCELERATION and a particular direction to e’ beam. The supply voltage is very high (1500)v. 16 16 May, 2017

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18. DEFLECTING PLATES There are two types of deflecting plate- VERTICAL DEFLECTING PLATE- resposible for y axis portion of graph. HORIZONTAL DEFLECTING PLATE- resposible x axis portion of graph. Vertical charge plate 2.Horizontal charge plate 18 . 16 May, 2017

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20. Animation of Cathode ray tube: 20 16 May, 2017

21. FLUORESCENT SCREEN: Fluorescent screen is a transparent screen Coated with Fluorescent material ( phosphorus ). Phosporous emit low frequency (visible spectra) light when it absorb the kinetic energy of electron. 21 16 May, 2017

22. SUMARRY OF CRT 22 16 May, 2017

23. ADVANTAGES OF CRO- RESOLUTION AND ASPECT RATIO- IT OPERATES AT ANY RESOLUTION,GEOMETRY AND ASPECT RATIO WITHOUT THE NEED FOR RESCALING THE IMAGE. HIGHEST RESOLUTIONS- IT RUNS AT THE HIGHEST PIXEL RESOLUTIONS GENERALLY AVAILABLE. HIGH CONTRAST LEVEL- IT PRODUCES HIGHEST CONTRAST LEVEL SUITABLE FOR USE EVEN IN DIMLY LIGHT OR DARK ENVIRONMENT. FAST RESPONSE- CRT GIVES FAST RESPONSE TO THE SIGNAL SO IT IS BEST FOR A RAPIDLY MOVING AND CHANGING WAVE. 23 16 May, 2017

24. DISADVANTAGES OF CRO- VERY SENSITIVE- SENSITIVE DEVICE AND REQUIRES COMPLETE ISOLATION FROM NOISE PRONE RESOURCES. PHYSICAL- THEY ARE VERY LARGE ,HEAVY AND BULKY.THEY CONSUME A LOT OF ELECTRICITY AND PRODUCE A LOT OF HEAT. BRIGHTNESS- RELATIVELY BRIGHT BUT NOT AS BRIGHT AS LCD’S. ITS NOT SUITABLE FOR VERY BRIGHTLY LIT ENVIRONMENT. CONTROL TERMINALS- THERE ARE LOTS OF CONTROL TERMINALS OVER THE CONTROL PANEL THAT LEADS TO A GREATER COMPLEXITY OF THE DEVICE MAKING IT DIFFICULT TO USE. 24 16 May, 2017

25. USE & APPLICATION OF CRO TO SEE THE WAVEFORMS - we can see the waveform of input signal with the help of CRO. FREQUENCY MEASUREMENT- Using a CRO we can determine the frequency of the unknown waveforms. Mathematically: (y axis value X CH*)=T(time period) So, Frequency=1\T. VOLTAGE MEASUREMENT- Y AXIS of waveform give the amplitude value of input signal in volt. 25 16 May, 2017

26. IT IS USE IN DESINE OF NEW CIRCUIT- CRO is strictly advise to see the exact output of new develop circuit. And to check the defective components in new circuit. IT IS BASICALLY USE IN SCIENTFIC AND ENGINEERING APPLICATIONS. 26 16 May, 2017

27. REFRENCES: AK SAWHNEY- Electronic instrumentation and measurement H.S KALSI- Electronic instrumentation and measurement DAVID A.BELL -Electronic instrumentation 27 16 May, 2017

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