Lissajous patterns are usually of two types. One voltage is used to produce vertical deflection, while the second is used to give the horizontal deflection. The main function of these amplifiers is to amplify the weak the weak signals so that the amplified signal can produce the desirable signals. The resultant pattern consists of a circle of spots in which the ratio of the high frequency to the low frequency is equal to the number of spots divided by a suitable integer 'n' that is less than the number of spots. A CRO (Cathode Ray Oscilloscope) is an electronic instrument used for studying various electrical & electronic parameters and behaviors. Thus the phase difference between two sinusoidal voltages of equal frequency can be determined by measuring dv0 and Dv. So the condition for having a Lissajous pattern on the CRO screen is. The equipotential surfaces are marked by the dotted lines which are curved in shape. Another easy way to measure current is to use a clamp-on current probe with an oscilloscope. Let there be two sinusoidal voltage signals given by. In order to find out the expression for the deflection, let us consider a system as shown below: In the above system we have two plates A and B which are at potential +E and 0 respectively. combination in series. At ElectronicsPost.com I pursue my love for teaching. When a beam of electron is incident at angle A to the normal then it deflects by angle B after passing through the surface S as shown in the figure given below. In an oscilloscope, the CRT generates the electron beam which are accelerated to a high velocity and brought to focus on a fluorescent screen. ... Optical Communication Lab - Viva Questions With Answers 1. The pattern will be the same for different values of 'n' so that the proper value of this integer must be determined from other information such as prior knowledge for approximate frequency. Since CRT is the heart of the oscilloscope, we are going to discuss its various components in detail. Thus, eE is loss in potential energy and 1/2mv1/2 is the gain in kinetic energy. A cathode ray oscilloscope is used to study waveforms, transients, time based or Since, the two anodes are at high positive potential, therefore, they produce a field which acts as electrostatic lens to converge the electron beam at a point on the screen. What are the important CPU registers in the 8085 microprocessor? What does CRO stand for in Engineering? Indeed, it is the only thing that ever has.” …………and we strongly believe on …, Measurement of Electrical Quantities with a CRO Notes for Electronics Engineering 1st Year. In a Lissajous pattern ratio of frequency of vertical signal to the frequency of horizontal signal is equal to the ratio of positive Y-peaks to positive X-peaks in that pattern. A cathode ray oscilloscope is a very fast X-Y plotter that can display an input signal versus time or another signal.… This is the simplest method to determine the frequency relation of two sine wave voltages. Horizontal and vertical deflection plates are fitted between the electron gun and the screen so that these can deflect the beam according to the input signal. In TTL circuits also, input transistor T 1 is a multi-emitter transistor driving the phase-splitter transistor T 2 . The three methods commonly used for measurement of frequency using CRO are listed below. A Lissajous pattern is a pattern which is stationary on the screen of a CRO. The Cathode Ray Oscilloscope is an instrument which we use in laboratory to display measure and analyse various waveforms of various electrical and electronic circuits. Using a CRO , the wave shapes of alternating currents and voltages can be studied. The pattern will be stationary when the ratio of the two frequencies is correctly a ratio of integers. To deflect the electron beam on the screen in horizontal direction i.e. Related abbreviations. This prevents the walls from charging to a high negative potential. The ratio of horizontal to vertical frequency is given by the number of times the figure (pattern) is tangent to the horizontal line divided by the number of times its end is tangential to the vertical line. Let us discuss the construction of cathode ray tube in order to understand the construction of cathode ray oscilloscope. It is an extremely useful and the most versatile instrument in the electronic industry. Now let us derive an expression for deflection of this beam. The control grid controls the amount of current flow as in standard vacuum tubes. The inner wall of CRT between the neck and screen are usually coated with a conducting material known as aquadag. When the mid-point of the series combination is taken as reference the voltages out of the other two terminals will have a phase difference of 90°. Ans if the potential on the plates is reversed, the spot of light will be deflected downwards i.e. At point C in time, once again the voltage is zero so the spot comes back to the central position on the screen. And, if you really want to know more about me, please visit my "About" Page. Graphical meaning of dv0 and Dv are shown in the figure. The figure below shows various parts of a cathode ray tube (CRT) . Basically the cathode ray tube consists of five main parts and these main parts are written below: Now we discuss each of the above part in detail : It is the source of accelerated, eenergisedand focused beam of electrons. (Phase measurement can also be made in this way). The equipotential surfaces are also shown in the diagram which is perpendicular to the direction of electric field. The plate A is at potential + E while the plate B is at potential – E. The direction of electric field is from A plate to plate B at right angle to the surfaces of the plate. I am Sasmita . Where, e is the charge on electron, E is the potential difference between the two plates, m is the mass of electron, and v is the velocity of the electron. What does CRO stand for in Electronics? Construction of Cathode Ray Oscilloscope Notes for Electronics Engineering 1st Year Cathode Ray Oscilloscope | CRO: The Cathode Ray Oscilloscope is an instrument which we use in laboratory to display measure and analyse various waveforms of various electrical and electronic circuits. Read More. The following block diagram shows the general-purpose CRO contraction.The CRO recruits the cathode ray tube and acts as a heat of the oscilloscope. The electron beam is deflected during its journey in response to the applied electrical signal. By the conservation of energy, we have loss in potential energy when the electron moves from cathode to accelerating anode should be equal to gain in kinetic energy of electron. For accomplishing these tasks various electrical signals and voltages are needed, which are provided by the power supply circuit of the oscilloscope. Your email address will not be published. Cathode ray oscilloscope uses luminous spot which is produced by striking the beam of electrons and this luminous spot moves in response variation in the input quantity. Due to the positive potential of about 10,000 V on the accelerating anode which is much larger than on the focusing diode, the electron beam is accelerated to a high velocity.