Re: Function of component in flash tube trigger circuit?

Sam Goldwasser <sam@xxxxxxxxxxxxxxxxxxxx> wrote in message
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"Rheilly Phoull" <rheilly@xxxxxxxxxxxxxx> writes:

"N_Cook" <diverse@xxxxxxxxx> wrote in message
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http://home.graffiti.net/diverse:graffiti.net/sf2.jpg
No markings, a black potted box 7x7x 15mm external dimensions.
If a stepup transformer , why so small?

0.3 ohms between blue and red lead and 144 ohms between blue and brown
lead which goes directly to the trigger filament around the flash
tube.
Red goes to ground and blue wire goes via 0.2uF, 250V capacitor to the
SCR
cathode. 22mH and 20uH inductance
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

If you dont like small put it in a larger box, manufacturers are not
known
for extragance and they tend to use the minium specs components.
Perhaps you may like to reword the question ?

It is definitely the trigger transformer. Typically a few primary turns,
a few hundred secondary turns, takes 150 V from a capacitor discharged
through the shutter contacts or an SCR, and produces 10kv or more to
the trigger wire or reflector of the flashlamp. But essentially no
current.

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What seems strange is this transformer must be half or third of the volume
of the ones in compact camera flashes but the tube is perhaps 100x the
volume of the tube in one of those cameras (1cm diameter, 20cm long). Don't
know the joules rating of this one, a large studio flash unit, but 530V
standing voltage. Perhaps 2m of wire wrapped around the flash tube, as
trigger, all in all seems inadequtely tiny in comparison.

I think I'll try 2 camera ones in series with 100 ohms initially to try and
localise why not triggering. I may try subbing this tiny stepup transformer
with one 3 times the size from a compact camera, as am wondering if it could
be internally arcing actoss turns.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





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