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DC Restoration
HI Andy,
Maybe you have some more ideas on the DC restoration in old sets. All the stuff I grew up with, with the exceptiion of Color sutff, had no DC restoration. I assumed they thought they were saving money, or that maybe they thought people didn't like blacked-out scenes. But then when you go back a little further in time, a lot of the really old (1949 and back) sets did have DC restoration, and either RF HV or flyback HV. Because they had DC restoration they didn't need any H or V retrace blanking ckts. But the problem they did have was raster blooming, since they had no HV regulators. Thus on bright scenes the raster would enlarge due to the falling anode voltage. No DC resoration took care of this problem since the average scene illumination was alway the same, and thus the anode current was a constant after the video coupling capacitors settled from scene to scene. But it was necessary to add retrace blanking since the picture black level was all over the place. I am guess this is the reasoning that went on with the mfr's. What do you think?
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CORK
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