At 01:04 3/1/03, you wrote:
On Sat, 1 Mar 2003, John A. Lind wrote:
> Any clues as to what's going on and why OM-4/OM-2S won't trigger it
will be
> very much appreciated!
The OM-4/2S flash trigger is driver by an SCR instead of a mechanical switch.
Perhaps the circuit needs a minimum load present in order to operate and your
little device may not provide enough load. I'm not familiar enough with the
circuit to say for sure, but it's something to consider.
-mark
Mark,
Thanks for your reply . . . this is along the lines of what I suspect, as
the unit works with mechanical flash triggering (e.g., OM-1n).
If this is the case, is it possible a resistor on the order of about 220 to
1k ohms in series or parallel with the flash contacts resolve this (create
enough "load" when the OM-2S/OM-4 fire)? With a low trigger voltage of
barely over 6VDC, the unit undoubtedly has some form of circuit through an
SCR [??] or TRIAC [??] to present a low voltage on its contacts.
I also found a couple of simple circuits for optocoupler triggering. One
only has four components, but I'd rather keep this as simple as possible
and not rip the thing completely apart to reverse engineer its circuit . .
. although I'm thinking that may be the only way out.
Thanks,
-- John
PS: Since I've discussed possibly opening up an electronic flash . . .
Anyone thinking about opening an electronic flash up should be knowledgable
about how to safely and properly discharge high voltage, high capacity
capacitors . . . and verify they are, indeed, discharged . . . before
working around them. Even with this very low powered unit (in Watt-Seconds
of IR output), I have little doubt there is a 300VDC to 500VDC electrolytic
with enough capacitance in the hundreds of uF range to kill under the right
(wrong) circumstances. At that voltage and capacitance, it's more than
enough energy. I've been "zonked" across a room by over 500VDC and was
very fortunate the source was such low current capacity and my contact with
it was for such a short time (milliseconds) that I lived to tell the
tale. Even so, the experience was definitely no fun and I was in some pain
for a while afterward.
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