Oscilloscope

An 'oscilloscope', previously called an 'oscillograph', and informally known as a scope or o-scope, CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope), is a type of electronic test instrument that graphically displays varying signal voltages, usually as a two-dimensional plot of one or more signals as a function of time. Other signals (such as sound or vibration) can be converted to voltages and displayed.The Braun tube was known in 1897, and in 1899 Jonathan Zenneck equipped it with beam-forming plates and a magnetic field for sweeping the trace. Early cathode ray tubes had been applied experimentally to laboratory measurements as early as the 1920s, but suffered from poor stability of the vacuum and the cathode emitters. V. K. Zworykin described a permanently sealed, high-vacuum cathode ray tube with a thermionic emitter in 1931. This stable and reproducible component allowed General Radio to manufacture an oscilloscope that was usable outside a laboratory setting.After World War II surplus electronic parts became the basis of revival of Heathkit Corporation, and a $50 oscilloscope kit made from such parts was a first market success.The basic oscilloscope, as shown in the illustration, is typically divided into four sections: the display, vertical controls, horizontal controls and trigger controls. The display is usually a CRT (historically) or LCD panel laid out with horizontal and vertical reference lines called the graticule. CRT displays also have controls for focus, intensity, and beam finder.Some oscilloscopes have cursors. These are lines that can be moved about the screen to measure the time interval between two points, or the difference between two voltages. A few older oscilloscopes simply brightened the trace at movable locations. These cursors are more accurate than visual estimates referring to graticule lines.HeterodyneAC hum on sound.Sum of a low-frequency and a high-frequency signal.Bad filter on sine.Dual trace, showing different time bases on each trace.The following section is a brief summary of various types and models available. For a detailed discussion, refer to the other article.