In article
,
Brian Reay wrote:

Percy Picacity wrote:


Not necessarily with static charges - which is what's on the CRT with the
HV removed.

Lightning is a static discharge, are you saying that doesn't smoke things?

The practical point is that the capacitance of a CRT is quite low,
limiting the amount of energy stored at a given potential. It's not a
negligible amount though. I suppose you could describe the charge on a
large power supply capacitor as a static charge too, but that is
definitely not negligible.


Energy stored in the cap is 0.5 CV^2

If V is large, as in a CRT, V^2 is going to be something to worry about.

On reflection, I agree. The capacitance of a CRT is about 10^7 lower
than of a PSU capacitor, but V^2 is about 10^7 higher - so about the
same energy.


That simple formula is the reason, in applications requiring a brief 'hold
up', PSUs in aircraft etc often have a voltage doubler on their input so
the can extend the hold up time by storing more energy for a given C.

(Adding a battery is not permitted by the aircraft design rules.)

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Percy Picacity