Continuing Education Oscilloscopes, Part One An introduction to the complex educational tool that has varied uses. by David Herres In this frst of a two-part series, we will confgured so that the location relative to the Y consider the oscilloscope as an educational tool. axis represents voltage, and the location relative It is a wonderful gateway into the world of to the X axis represents time. Crossing the axes electronics, and it seems there is no end to the at right angles to them are lines (known as multiple layers of elementary particle interaction “divisions”) that make it possible to gauge the it can reveal. voltage level of the signal at specifc time When one takes a new oscilloscope out of the intervals. Te trace so constituted may be box, the frst reaction may be, “What was I moving or static, but, either way, it conveys an thinking? How did I ever get myself into this? So immense amount of information about the signal many knobs and buttons, and endless cryptic being investigated. menus!” But don’t worry. Te operating manual, print or online, clarifes a great deal, and History remaining information gaps disappear one by To understand how the oscilloscope works, one as frst elementary and then successively Value: 1 it is instructive to take a look at its history, more complex exercises are performed. particularly in regard to two milestones: contact Te modern digital oscilloscope consists of probes; analog channels (usually two or four); triggering and the digital storage scope. Te hour analog-to-digital conversion; processing and frst oscilloscopes involved capturing (0.1 CEU) memory; and, fnally, waveforms by means of measuring voltages at a display (now various points along the circumference of a Approved for predominantly on a spinning rotor. A permanent record in the form Continuing fat screen). Typically, of a graphical image was made by hand drawing Education by Learning Objectives there are two axes, X the image on paper. Needless to say, frequency NAEC for CET® and Y, that intersect response was limited by the speed and and CAT®. After reading this article, you at the center of the endurance of the artist(s). EW Continuing should have learned about: screen. A spot of light Subsequent oscilloscope innovations were Education is moves vertically and ♦ Te history of the oscilloscope incremental. Te frst major breakthrough currently approved horizontally across ♦ Te principal components of involved use of a galvanometer, which moved a in the following the screen to form the an oscilloscope display pen across a strip of paper wrapped about a states: AL, AR, FL, trace, which is a ♦ Te purpose of the X and Y drum. It rotated at a constant clock-driven rate, GA, IL, IN, KY, MS, graphic axes which provided the time base. Similar MT, OK, PA, VT, VA, ♦ Important innovations in representation of the subsequent methods also involved moving WV and WI. Please oscilloscope development voltage applied at the parts, and because these machines were check for specifc ♦ input of the Disadvantages of TV course verifcation instrument. mechanical (as opposed to electronic), inertia conversion and the computer- of approval at www. based oscilloscope In its most of rest placed a severe limit on frequency elevatorbooks.com. common application, response. the oscilloscope is Continued May 2016 • ELEVATOR WORLD 55 Breakthroughs triggered-sweep oscilloscope, which An analog-to-digital converter in Hybrid equipment, where refected light facilitated a stable and coherent display of a conjunction with memory chips permit from a trembling mirror created waveform recurrent waveform. Tis expedient contemporary oscilloscopes to record and images on photographic paper, ramped permitted multiple waveform images to store a digital representation of any sort of oscilloscope frequency response as high as coincide on the oscilloscope screen, electrical waveform. Tis development 10 kHz by the 1920s. Later in that century, replacing the meaningless blur of light facilitated the fat-screen display. Together two substantial innovations occurred that resulting from lack of synchronization. An with efective triggering, digitization has made possible the oscilloscopes used unchanging frequency sweep input was not created a work platform that is immensely universally today. required for image stability. useful to engineers, technicians and Te frst of these was triggering, Te other signifcant development students to visualize diverse electronic introduced by Howard Vollum and Jack occurred prior to the 1980s, when Walter phenomena and solve many problems that Murdock, founders of Tektronix. In 1946, LeCroy, founder of LeCroy Corp., arise in research, development and they brought out the Tektronix Model 511 introduced the digital storage oscilloscope. maintenance. Types “Electronic technician” is a broad term and can include the electrical engineer who Replacement DOORS conceives of, designs and may be called upon to debug new innovations. 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It low-end market, while others have been harbor hazardous high voltages retained in takes diferent forms, typically an external and are currently investing in R&D, the electrolytic capacitors associated with USB or parallel-port device. Another type seeking to provide top-level quality and their power supplies. (High voltage levels of PCO consists of a card installed in the functionality. Te big players are are needed for the defection circuitry computer. For hardware, there is an Tektronix, LeCroy and Agilent (recently capable of moving the beam of electrons electrical interface providing isolation and spun of into Keysight Technologies but away from the center of the screen.) automatic gain controls, some analog-to- keeping essentially the same product line). Moreover, the cathode-ray tube (CRT) digital converters and bufer memory, or Tese vendors ofer high quality, very itself can store electrical energy. Ten, an internal digital signal processor. Display advanced and durable oscilloscopes that there is also such a thing as distributed and control interfaces are provided by the should be valuable for years to come. capacitance throughout the set. Te chassis computer, and it is for that reason that the must be removed from the cabinet and cost of a PCO is much less than that of a these hazardous voltages discharged to full-scale oscilloscope. ground potential before starting to work As may be expected, there are some on the set. If you are at all uncertain of the signifcant disadvantages in going the PCO procedure, call a professional to help with route, despite the surprising functionality this phase of the project. And, remember of some of the better instruments. Te that if the set is reenergized, the principal drawback is that the computer is discharging process will have to be a source of power supply and repeated. electromagnetic noise. If