how a cathode ray oscilloscope works

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The Oscilloscope is a type of electronic instrument that reads signal voltages and displays them on a screen in a 2d form. This is usually represented in a graph of one or more electrical potential differences (vertical axis) plotted as a function of time or of some other voltage (horizontal axis) The first type of oscilloscope was made up of a cathode ray tube, vertical amplifier, a time base, a horizontal amplifier and a power supply. This was known as an analogue scope which is different to the more modern digital scopes now in existence. cathode ray tube is an evacuated glass envelope, similar to that in a black-and-white television set, with its flat face covered in a fluorescent material (the phosphor). The screen is typically less than 20 cm in diameter, much smaller than the one in a television set. In the neck of the tube is an electron gun, which is a small heated metal cylinder with a flat end coated with electron-emitting oxides. Close to it is a much-larger-diameter cylinder carrying a disc at its cathode end with a round hole in it; it's called a "grid" (G1), by historic analogy with amplifier vacuum-tube grids. A small negative grid potential (referred to as the cathode) is used to block electrons from passing through the hole when the electron beam needs to be turned off, as during sweep retrace or when no trigger events occur. Illustration showing the interior of a cathode-ray tube for use in an oscilloscope. Numbers in the picture indicate: 1. Deflection voltage electrodes 2. Electron gun 3. Electron beam 4. Focusing coil 5. Phosphor-coated inner side of the screen However, when G1 becomes less negative with respect to the cathode, another cylindrical electrode designated G2, which is hundreds of volts positive referred to the cathode, attracts electrons through the hole. Their trajectories

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