Piers wrote:
>>
The label actually* says "Output DC 200V 10mA", so how about we add "and a
10mA fuse" to "with a bridge rectifier"?
I daresay there would be a ready-to-eat IC stabilizer available,......
Where's Tim Hughes when we need him?
<<
I have been off climbing in Yosemite so have not followed this thread but
seeing a few posts, here is the basic information. The output spec for the
transformer is complicated by the fact the transformer output is unsmoothed
rectified AC. That is, it is pulsating DC. The peak value will still be
close to 330V. The 10mA spec usually just means the transformer can produce
an averaged DC output of 200V at a rated load of 10mA, as measured with an
averaging DC meter voltmeter (sometimes RMS is used in a confusing way).
If we assume the peak voltage output, under ~0mA load (when cap fully
charged) is 330V, then RMS AC voltage from transformer (before rectifier)
should be 0.707*330V = 230V RMS unloaded. The difference from RMS to mean
(DC) for sinewave is something of the order of 10 0f I remember right, so
that gives an average DC rating of 207V unloaded for the transformer. Under
load the transformer regulation (leakage inductance etc) and resistance will
drop the voltage a bit so the200VDC spec is plausable. CH and others are
right that the transformer will deliver (and is designed to deliver) much
higher currents at start of charging. The T32 actually has it's own internal
resistor to limit the inrush current a bit from the external supply. (This
resistor in fact probably limits the charge rate a bit from a high power
pack like the Quantum.) The fact that the transformer may be overloaded
briefly is no big deal as the transformer's continuous rating is based on
the maximum allowed internal temperature rise of the wire insulation. The
wire+transformer has a large mass (and thus thermal time constant,10's of
minutes) so it it can take a much longer overload time to cause the
temperature rise to exceed the thermal rating. The worst case would be
shooting rapidly in succesion with full energy dump but even with 36
exposures it probably translates to a modest temperature rise.
230VRMS*10mA RMS = 2.3J/sec The T32 is ~70J/flash so the best case, average
charge rate must be ~70J/8sec = 9J/sec which is thus ~4 times higher than
the rated transformer spec! In reality the peak rate will be higher still
at start of cap charging.
Somebody suggested using a 110V to 220V "travel" step up transformer with
added rectifier. Since these are almost always auto-transformers ***with no
isolation*** this is potentially **absolutely lethal**. You could land up
with 110V line connected to the frame of your camera. DON'T EVEN THINK OF
DOING THIS.
Regards,
Tim Hughes
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|