The voltages require by CRT, horizontal amplifier and vertical amplifier are provided by the power supply block. Hence input signal and the sweep frequency can be synchronized. The signals which are used to activate the trigger circuit are converted to trigger pulses for the precision sweep operation whose amplitude is uniform. The saw tooth voltage produce by the time base circuit is amplified by the horizontal amplifier before it is applied to horizontal deflection plates. The spot is deflected by the saw tooth voltage at a constant time dependent rate. The saw tooth voltage produced by the time base circuit is required to deflect the beam in the horizontal section. Time base circuit uses a uni junction transistor, which is used to produce the sweep. Therefore, the input signal is delayed by a period of time. The input signal is not applied directly to the vertical plates because the part of the signal gets lost, when the delay Time not used. Usually, the vertical amplifier is a wide band amplifier which passes the entire band of frequencies.Īs the name suggests that, this circuit is used to, delay the signal for a period of time in the vertical section of CRT. The input signals are amplified by the vertical amplifier. When the electrons emitted by the electron gun strikes the phosphor screen of the CRT, a visual signal is displayed on the CRT. The major subsystem of a general purpose CRO consists of the following In the same way for CRO, the luminous spot of the electron beam acts as a stylus that moves over the display area in a response to input voltages. These are basically very fast x - y plotters that display input signal versus another signal. CRO is an extremely useful and versatile laboratory instrument used for the measurementĪnd analysis of waveforms and other phenomena in electronic circuits. The figure below shows various parts of a cathode ray tube (CRT). As a result, the electrical signal waveform is displayed visually. The electron beam is deflected during its journey in response to the applied electrical signal. The cathode ray tube or CRT is a vacuum tube of special geometrical shape which converts an electrical signal into a visual one.Ī CRT makes available a large number of electrons which are accelerated to high velocity and are brought to focus on a fluorescent screen where it produces a spot when strikes it. Since CRT is the heart of the oscilloscope, we are going to discuss its various components in detail. The signal to be viewed is supplied to the vertical deflection plate through the vertical amplifier, so that it can amplify the signal to a level that will provide usable deflection of the electron beam.Īs the electron beam is deflected in X-axis as well as Y-axis, a triggering circuit is provided for synchronising these two types of deflections so that horizontal deflection starts at the same point of the input vertical signal each time it sweeps. X-axis with constant time-dependent rate, a time base generator is provided in the oscilloscope. To deflect the electron beam on the screen in horizontal direction i.e. 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. Normal voltage supply is required for other control units of the oscilloscope. Low voltage supply is required for the heater of the electron gun to generate the electron beam and high voltage is required for the cathode ray tube to accelerate the beam. By deflecting the beam over the screen in response to the electrical signal, the electrons can be made to act as an electrical pencil of light which produces a spot of light wherever it strikes.įor accomplishing these tasks various electrical signals and voltages are needed, which are provided by the power supply circuit of the oscilloscope. This screen produces a visible spot where the electron beam strikes it. In an oscilloscope, the CRT generates the electron beam which are accelerated to a high velocity and brought to focus on a fluorescent screen. Īs we can see from the above figure above, a CRO employs a cathode ray tube ( CRT) ,which acts as the heart of the oscilloscope. The figure below shows the block diagram of a general purpose CRO. Block Diagram of CRO (Cathode Ray Oscilloscope): Different types of oscilloscopes are available in the market for various purposes. It can also be used for measuring voltage, current, power, frequency and phase shift. Using a CRO, the wave shapes of alternating currents and voltages can be studied. CRO is widely used for trouble shooting radio and television receivers as well as for laboratory research and design.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |