Function of component in flash tube trigger circuit?

[James Sweet]

surely there is only microbar of pressure in a xenon tube?
so nearer a vacuum
"in space no one can hear you scream"

According to an article I found, the pressure ranges from .01 to .1 Bar,
that's a LOT of gas compared to the vacuum of space.

You can get audible shockwaves in Nixie tubes by driving them multiplexed.
Those have a pressure of only a few mm.

 

[Sam Goldwasser]

Could you have a very marginal leak over a couple of months leading to
intermittant problems ?

I kind of doubt it, at least not at any level of probability that
matters. >

I would expect any leak to manifest itself as total failure in hours at the
most.

Agreed if it's a real leak. I suppose it's possible for there to be
some sort of internal contamination that manifests itself usage.

If you have the flashlamp, you could test for ionization.

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[Sam Goldwasser]

I've now tried 2 xenon beacon tubes in series and it works every time on
full or reduced settings. Also works every time with the piezo gaslighter
when iys ground plate is connected to the flash unit ground

I was always told that the clap of thunder was due to air refilling the gap
after being punched through by the lightening plasma arc.
That cannot be the reason for the pop when such xenon tubes fire as there is
no air inside them , why the pop?

There's rather dramatic shock wave inside when the lamp fires. This
is transmitted via the walls of the tube to the air outside. Keep in
mind that the pressure in these is a significant fraction of 1 atm, not
like a neon sign or HeNe laser!

What sort of power coming out as light in both cases.
Unknown original tube of 10mm diameter , 200 mm long
2 beacon tubes 6mm diameter, 140mm combined length

Supply is from 2 seriesed 1000uF capacitors with 300V on each
The beacon tubes are rated for 250V min , 500V maximum, nominal 400V
maximum energy input per flash: 45W /second, maximum flash rate at maximum
input power: 100/min

There is strike defeat, while recovering, sub-circuit and recovery time is
about 1/3 sec, don't know what it is with the original tube.

Is there a question buried here somewhere?

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[Sam Goldwasser]

surely there is only microbar of pressure in a xenon tube?
so nearer a vacuum "in space no one can hear you scream"

Actually, no. It may be near 1/2 atm.

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[N_Cook]

There's rather dramatic shock wave inside when the lamp fires. This
is transmitted via the walls of the tube to the air outside. Keep in
mind that the pressure in these is a significant fraction of 1 atm, not
like a neon sign or HeNe laser!


Is there a question buried here somewhere?

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Now I've separated the tube from the reflector enough to clean the tube in
the area where it descends through the reflector
http://home.graffiti.net/diverse:graffiti.net/xenon_tube.jpg
I can now see all is not well.
The cloudiness in the cathode end of the tube (only) is on the inside and
there is a patch of distinct blackening marked with a yellow line.
General black background is conductive foam for picture contrast , the
yellow wire is the trigger wire connected to the loops around the tube, no
silvering. The gaps 2 turns up of the spiral wrap at both anode and cathode,
would they be breaks or like that at manufacture?
It is after all 25 years of commercial photo studio use.
The slave action via LDR also checks out

Powering up, switching off, and triggering with piezo and measuring before
and after V then 42 joules per discharge per beacon tube. It may be
advantageous to wire in a pair more of these beacon tubes to make 4 , to
spread the load, at 2.50 GBP each compared to 70GBP for a not exact size and
fit single tube replacement.

 

[Sam Goldwasser]

Now I've separated the tube from the reflector enough to clean the tube in
the area where it descends through the reflector
http://home.graffiti.net/diverse:graffiti.net/xenon_tube.jpg
I can now see all is not well.
The cloudiness in the cathode end of the tube (only) is on the inside and
there is a patch of distinct blackening marked with a yellow line.
General black background is conductive foam for picture contrast , the
yellow wire is the trigger wire connected to the loops around the tube, no
silvering. The gaps 2 turns up of the spiral wrap at both anode and cathode,
would they be breaks or like that at manufacture?

It is after all 25 years of commercial photo studio use.
The slave action via LDR also checks out

The issue of the 2 turns of wire is probably irrelevant. The discoloration
is also not surprising after a lot of use. What do you want from the poor
thing after 25 years in a studio environment?

Powering up, switching off, and triggering with piezo and measuring before
and after V then 42 joules per discharge per beacon tube. It may be
advantageous to wire in a pair more of these beacon tubes to make 4 , to
spread the load, at 2.50 GBP each compared to 70GBP for a not exact size and
fit single tube replacement.

How much is your time worth? Kludging something with cheap flashlamps
may result in it failing quite quickly. If you're just doing this to
be able to demonstrate that it works, fine. If this is for a pyaing
customer, install the proper flashlamp!

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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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