Quote:
Originally Posted by old_tv_nut
You are not loading down the video when the brightness control is at the end, because the diode only conducts on sync.
However, in the original circuit, the average cathode video voltage is between 0 and 120, but with the diode, the sync peaks are between 0 and 120, and the average is lower (making a brighter picture). You may need to look for a higher voltage for the positive end of the brightness control and put a resistor between the other end of the contol and ground, to get the syncs to be cutoff and normal video to be normal.
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I just noticed this - will review the schematic and waveform to make sure I understand