Moose wrote: >>nobody else posting on this
topic seems to have read<<. (Mark's post saying the OM3 is all mechanical
switches)
As the original poster of this erroneous notion, I did post and agree
with Mark immediately after he posted the correction to my OM3 misconceptions.
I guess it got more confused after somebody "confirmed" it had a thyristor.
The only good reason for a thyristor would be if the OM3 offered OTF flash mode.
Moose also wrote:
"Another form of thyristor, a triac, is much like two SCRs wired up in
parallel with their polarities reversed and their gates connected
together. Thus it can control current in both directions. Although used
in all kinds of circuits, the one most familiar to the average
non-technician is the incandescent light dimmer. One of its most
important uses is in automatic electronic flashes."
I don't think there is a good reason to use a triac for flashes since the
current flow is kept pretty much unidirectional to protect the flashtube from
reverse current damage and the triac has a higher voltage drop in general,so it
would just increase losses. I certainly have never seen one in a flash.
In modern flashes, particularly small flashes inside the cameras, SCR's are
typically replaced by IGBJT's (insulated gate bipolar transistors) which are
much easier to use for red-eye reduction,multi-flash, Super fp flash etc. They
are more expensive and difficult to use for very high power flashes so I would
guess the SCR's are still device of choice there and for very cost sensitive
applications.
>>But I don't like muddled info.<<
Agreed, given no OTF flash in the OM3 and works without batteries, the chances
of there being a thyristor in there are just about 0.
Regards,
Tim Hughes
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