My initial thought was that the stored energy is constant whether
there were two heads or one, the single head would be optimized to
work with the controller, and that the two flash heads aren't going to
focus their light on the same area thus two heads aren't likely to
give the same GN in actual use.
Your comments sparked some interesting ideas though. The main thought
with the current flow is that it is roughly half for two heads then
the duration will be twice as long and the light intensity half as
much. Along with the lower intensity the color temperature would also
shift (?)
A 10% change in energy would reduce the GN to 28 x sqrt(0.9) = 26.6
Someone posted a link (you?) to a website that described flash
circuits. One of the things I vaguely remember was that when one of
the circuits quenched the flash, it dumped energy into a separate
capacitor. It claimed that the energy was mostly recovered but it
wasn't clear how they would get it back into the main energy storage.
This wouldn't appear to make any difference in this case since you
said they dump the energy into the tube until it quits conducting to
determine the max GN.
-jeff
On 7/20/07, Tim Hughes <timhughes@xxxxxxxx> wrote:
>
> Jeff,
>
it is much easier to just look at start energy in cap and end energy
in cap and know that
> since load is resistive all the change in energy goes to the tubes. (halve
> that energy for each
> individual tube).
> So original 1 tube actual energy used :
> 0.5C*(330V)^2-0.5C*(60V)^2
> and two tubes series (sum energy to both tubes) is a bit reduced:
> 0.5C*(330V)^2-0.5C*(120V)^2
> Where C is flash capacitance.
> (@60V extinction, this is ~10% reduction of total delivered energy)
>
> Normally they don't cut off flow, the flash tube conducts until the tube self
> extinguishes at
> something like ~60V.
>
> Tim Hughes
>
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