rtbcomp
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I thought the very old telly's had EHT transformers,
Yes, AKA line output or flyback transformer. They were part of the horizontal scan circuit, the flyback is a very fast pulse which drives the spot on the screen from right to left at the end of each line, this pulse produced a very high voltage in the EHT secondary (that big coil of very fine wire) which was rectified by that little valve with three wires sticking out of it.
It would be impractical to lift this circuit to provide a standalone power supply as it is triggered by the line sync pulses from the tuner, if my own memoery serves me right!