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Cathode Ray Oscilloscope Satish Chandra

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Page 1: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Cathode Ray Oscilloscope

Satish Chandra

Page 2: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Cathode Ray Oscilloscope

• The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical quantity.

• The waveform is generated in such a way that the amplitude of the signal is represented along Y-axis and the variation in the time is represented along X-axis.

• CRO is the measuring device as well as it can generate waveforms in terms of amplitude and time because it is very easy to measure the amplitude of the voltage signal to determine its intensity.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 3: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Block Diagram of Oscilloscope

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 4: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Parts of Oscilloscope

• Cathode Ray Tube

• Time Base Generator

• Vertical Deflection System

• Horizontal Deflection System

• Delay line Circuit

• Trigger Circuit

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 5: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Cathode Ray Tube

• The cathode ray tube consists of an electron gun, vertical deflection plates, horizontal deflection plates, phosphor screen and electrode.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 6: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Cathode Ray Tube

• The electron gun generates the beam of an electron when the voltage is applied to it.

• It must be noted that the voltage applied to the electron gun is quite low while the voltage applied for accelerating the beam of electron is very high.

• The beam of an electron when generated by the electron gun is passed from vertical deflection plate and horizontal deflection plate and it creates the pattern on the phosphor screen.

• When the light ray strikes the phosphor screen, a bright spot or luminous spot is created.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 7: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Cathode Ray Tube

• The electron beam suffers from deflection due to the presence of vertical deflection plate and horizontal deflection plate.

• The extent of deflection is directly dependant on the signal which is received from the output terminal of the vertical amplifier and the horizontal amplifier.

• It is due to this deflection phenomenon the luminous spots are created on different parts of the screen, and thus waveform can be seen by these luminous spots.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 8: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Time-Base Generator

• The circuit that produces a linearly varying voltage or current with time is known as Time-Base Generator.

• It is basically a function generator that generates a saw-tooth waveform of high frequency.

• These circuits are also known as sweep circuits. This is so because they are used to sweep the beam of electron across the screen in a horizontal direction in CRO.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 9: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Time Base

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 10: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Cathode Ray Tube

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 11: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Vertical Amplifier

• The vertical amplifier receives the input from the signal which is to be measured.

• The vertical amplifier receives the input signal and then amplifies it so that the signal of high intensity is supplied to the vertical deflection plate.

• If a low-intensity signal strikes the vertical deflection plate, the electron beam will not be deflected effectively to create the bright spots on desired points on the screen.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 12: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Horizontal Amplifier

• The horizontal amplifier generates the signal which provides voltage to horizontal deflection plates.

• The horizontal deflection plates deflect the beam along the horizontal direction. This is helpful to create the waveform along with the time domain.

• The deflection of the electron beam in the horizontal direction will be effective only when the signal applied from the output of the horizontal amplifier is high enough to create the bright spots at the desired location on the phosphor screen.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 13: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Delay Line Circuit

• When the signal from the vertical amplifier is fed to the vertical deflection plates, then some part of the amplified signal is supplied to the time base generator.

• This trigger pulse generated from the time-based generator is amplified with the help of the horizontal amplifier.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 14: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Delay Line Circuit

• After this, it is fed to horizontal deflection plates. This process requires approximately 100ns.

• Thus, it is crucial to delay the signal generated by the vertical amplifier too in order to maintain synchronization.

• The delay line is essential because there is the delay when any electronic signal passes through the electronic circuitry.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 15: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Trigger Circuit

• The trigger pulse is generated by the time base generator to provide synchronization of the signals obtained from the horizontal and vertical amplifier.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 16: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Working of Cathode Ray Oscilloscope

• The electron gun generates the beam of electrons; these beam consists of several electrons moving towards phosphor screen. The control grids are also used in CRT to control the intensity of electrons.

• The accelerating anodes are used to increase the velocity of electrons so that they strike the phosphor screen with high speed and thus forms a bright spot.

• The beam creates the luminous spot at the different points on the screen. This becomes easy with the help of deflection plates which deflects the electron beam through various angles. 1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 17: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

CRT

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 18: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

Applications of Oscilloscope

• An oscilloscope is used for voltage measurement, current measurement, measurement of other physical quantities after conversion to electrical form.

• Cathode ray oscilloscope is also used in the laboratory to study the output waveforms of various signals. Besides, it can also be used to measure their phase and frequency.

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur

Page 19: Cathode Ray Oscilloscope - satish0402.weebly.com · Cathode Ray Oscilloscope •The cathode ray oscilloscope (CRO) is the instrument which generates the waveform of any electrical

END CRT

1/11/2020 Dr. Satish Chandra, PPN College, Kanpur