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Cathode Ray Tube (CRT) A cathode ray tube is the heart of the CRO. The below fig shows the various parts of CRT. 1.        Glass Envelope: It is conical highly evacuated glass housing maintains vacuum inside and supports the various electrodes. The inner walls of CRT between neck and screen are usually coated with the conducting material called aquadag. This coating is electrically connected to the accelerating anode so that electrons which accidently strike the walls are returned to the anode. This prevents the walls of the tube from charging to a high negative potential. Pic 1. Cathode Ray Tube 2.        Electron Gun Assembly: the arrangement of electrodes which produce a focussed beam of electrons is called electrongun. It essentially consists of an indirectly heated cathode, a control grid, a focussing anode and an accelerating anode. The control grid is held at negative potential with respect to cathode whereas the anode a...

A protector system that is applied at the beginning of the television technique, therefore most often found on old aircraft models. If the high voltage anode of the picture tube flyback tranfo exceed the permitted limit, the picture tube can generate x-rays from the anode and shadowmask are bombarded by electrons at high speed. To avoid this problem then mounted x-ray surge protector circuit , which automatically "horizontal section will be turned off" if the high voltage from the flyback over. X-Ray vertical protect The workings of x-ray protector: High voltage flyback sampled (generally taken from the pin-heater), rectified and is derived using a divider (devider) that uses a resistor-type high-precision resistor. Sample voltage is used to determine whether the condition is normal flyback voltage or over. A "zener diode" as a voltage sensor connected to the sample. In normal conditions the amount of the sample voltage is below the zener voltage of diode so that th...