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Tham khảo tài liệu 'oscilloscopes episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 2 The basic oscilloscope Chapter 1 briefly described how an oscilloscope draws its trace with a spot of light produced by a deflectable beam of electrons moving across the screen of its c.r.t. cathode ray tube . At its most basic therefore a cathode ray oscilloscope further details of cathode ray tubes can be found in Chapter 9 consists of a timebase circuit to move the spot steadily from left to right across the screen at the appropriate time and speed and some means usually a Y deflection amplifier of enabling the signal we wish to examine to deflect the spot in the vertical or Y direction. Alternatively some other display technology such as LCD may be used though in this case the instrument is usually a digital storage type of oscilloscope. In addition of course there are a few further humble essentials like power supplies to run the c.r.t. or LCD display and circuitry a case to keep it all together and a Y input socket plus a few controls on the front panel. Figure 2.1 is a block diagram of such an instrument. This type of oscilloscope more or less sophisticated as the case may be belongs to what was traditionally by far the commonest and most important category the real-time oscilloscope. This means simply that the vertical deflection of the spot on the screen at any instant is determined by the Y input voltage at that instant. Not all oscilloscopes are real-time instruments Figure 2.2 attempts to categorise the various types available. The distinction between real-time instruments and others is not absolute and clear cut but the fine distinctions need not worry US here. A really basic oscilloscope then is one with the necessary facilities for examining a repetitive waveform. An instrument with but a single Y input corresponding to Figure 2.1 and the extreme left-hand branch of Figure 2.2 meets this description. With such an instrument the relative timing between the waveforms at different points in a circuit can be established albeit indirectly by using the .
