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Television Technical Theory
If you come across an older television set, you may find that it has two knobs
called “horizontal hold” and “ver tical hold.” If yours has these, experiment with
them. With a bit of fiddling with the vertical hold control, you can make the picture
“roll” vertically down the screen. The “black bar” you now see in the middle of the
screen is the ver tical inter val. If you play around with the horizontal hold control
you may be able to cause the television set to lose horizontal lock as well. Modern
televisions don’t have these controls anymore, because synchronization technology in home receivers is now so reliable that we don’t have to make these adjustments. If you have only a newer television and can’t experiment for yourself, the
illustrations here show you what vertical and horizontal intervals look like.
How the parts of the composite video signal affect the monitor