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[OM] F280 CCT Design Trivia

Subject: [OM] F280 CCT Design Trivia
From: Tim Hughes <timhughes@xxxxxxxx>
Date: Thu, 12 Feb 2004 00:24:09 -0800 (PST)
Looking through the F280 schematics and service manual, the threshold for Flash 
ready detection is
set at an energy level of 79% of full charged energy level. Giving an effective 
GN of ~89% of
fully charged.
 
The voltage step-up invertor has a proper feedback loop controlling the output 
voltage which
should help speed up charging to fully charged voltage. (T32/20 use blocking 
osc self regulation,
which is not so fast to charge, or so consistent).  

The flash capacitor output voltage is only 265V, much lower than the almost 
universal 330V used in
portable flash units. This is probably related to operating the tube in super 
FP mode where it
needs to be retriggered reliably. This is an interesting choice, since normally 
it becomes tougher
to trigger at low tube voltages and probably means the flash tube is running 
with an unusal fill
pressure or gas mix to allow fast triggering.

Regards,
Tim Hughes


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