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Internal degaussing coils in CRTs are generally much weaker than external degaussing coils, since a better degaussing coil takes up more space. A degauss circuit induces an oscillating magnetic field with a decreasing amplitude which leaves the shadow mask with a reduced residual magnetization. A degaussing in progress
Color CRT displays in TV sets and computer monitors often have a built-in degaussing (demagnetizing) coil mounted around the perimeter of the CRT face. Upon power-up of the CRT display, the degaussing circuit produces a brief, alternating current through the coil which fades to zero over a few seconds, producing a decaying alternating magnetic ...
The NTSC color system changed from the black-and-white 60-fields-per-second standard to 59.94 fields per second to make the color circuitry simpler; the 1950s TV sets had matured enough that the power frequency/field rate mismatch was no longer important. Modern TV sets can display multiple field rates (50, 59.94, or 60, in either interlaced or ...
The Westinghouse H840CK15 was the second consumer all-electronic color television set offered for sale in the United States on February 28, 1954. [1] It used the 15GP22 cathode ray tube. The set was discontinued about six months after its introduction [ 2 ] because of larger and less expensive 19 and 21-inch color sets becoming available in ...
In conventional black-and-white (B&W) televisions, the CRT screen has a uniform coating of phosphor that emits white light when struck by electrons.The beam from an electron gun at the back of the tube is deflected (most commonly) by the varying fields from magnetic coils so it may be directed at any point on the screen.
Thus, the new color television standard reduced the line rate by a factor of 1.001 to 1/286 of the 4.5 MHz audio subcarrier frequency, or about 15734.2657 Hz. This reduced the frame rate to 30/1.001 ≈ 29.9700 Hz, and placed the color subcarrier at 227.5/286 = 455/572 = 35/44 of the 4.5 MHz audio subcarrier.
Later, the General Colornetron adopted this approach. Successor Chromatron tubes experimented with different color phosphors to obtain the correct combination of brightness and persistence. Finally a rather large copper box or cage was mounted externally to the bell to reduce the remaining radiation from the grid coil.
A series of resistor–capacitor circuits (RC circuits) can be cascaded to form a delay. A long transmission line can also provide a delay element. The delay time of an analog delay line may be only a few nanoseconds or several milliseconds, limited by the practical size of the physical medium used to delay the signal and the propagation speed ...