Function of component in flash tube trigger circuit?

[N_Cook]

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

 

[Rheilly Phoull]

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

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 ?

 

[John Tserkezis]

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?

As per the other poster, it's likely the trigger transformer.
They're usually quite small, as they have few primary turns, lots of
secondary, and since the wire is quite thin (impedance isn't a problem as they
don't supply any appreciable current), they end up quite small.

 

[Sam Goldwasser]

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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[N_Cook]

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

 

[James Sweet]

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.

The size is virtually irrelevant, as Sam says, almost no current is
required. I've used a tiny trigger transformer salvaged from a disposable
camera to trigger a huge (about 8" long) 1KJ flash tube. Some are bigger,
some are smaller, it has more to do with age, manufacturing process, and the
need for compactness.

 

[N_Cook]

The size is virtually irrelevant, as Sam says, almost no current is
required. I've used a tiny trigger transformer salvaged from a disposable
camera to trigger a huge (about 8" long) 1KJ flash tube. Some are bigger,
some are smaller, it has more to do with age, manufacturing process, and the
need for compactness.

Is it possible to have a non-functional tube with no signs of problems ,
like the black patches on the ends of a fluourescent tube that is on the way
out.

This one looks perfect other than the glass is a bit dirty on the outside,
because the distributed trigger stops any cleaning. Not been dropped, no
cracked glass, no odd looking deposits on the elctrodes or on the inside of
the glass.

 

[James Sweet]

Is it possible to have a non-functional tube with no signs of problems ,
like the black patches on the ends of a fluourescent tube that is on the
way
out.

This one looks perfect other than the glass is a bit dirty on the outside,
because the distributed trigger stops any cleaning. Not been dropped, no
cracked glass, no odd looking deposits on the elctrodes or on the inside
of
the glass.

Yes, it's possible, but not terribly likely. You should be able to test it
by applying voltage to the tube and using a piezo flame igniter to trigger
it.

 

[N_Cook]

Yes, it's possible, but not terribly likely. You should be able to test it
by applying voltage to the tube and using a piezo flame igniter to trigger
it.

I like that suggestion, just connect the arc pin of a piezo gaslighter to
the trigger wire, when the standing voltage is across the tube- pure,
minimilist test.

 

[hr(bob) [email protected]]

I like that suggestion, just connect the arc pin of a piezo gaslighter to
the trigger wire, when the standing voltage is across the tube- pure,
minimilist test.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list onhttp://home..graffiti.net/diverse:graffiti.net/- Hide quoted text -

- Show quoted text -

Let us inow what you find.

 

[N_Cook]

I like that suggestion, just connect the arc pin of a piezo gaslighter to
the trigger wire, when the standing voltage is across the tube- pure,
minimilist test.

onhttp://home.graffiti.net/diverse:graffiti.net/- Hide quoted text -

- Show quoted text -

Let us inow what you find.


How do you test for lack of air in a xenon tube?
Putting a neon bulb and dropper over the trigger transformer gave plenty of
strike even in room lighting.
I've an old reserve piezo gas lighter that the metal grounding barrel on the
end falls off, ideal for testing this tube, but no flash over.
Trying to find a medium size xenon tube I have somewhere or will try with a
couple of copmpact camera xenon tubes or one removed from a xenon burglar
alarm flasher, both with some sort of droppers, later today

 

[N_Cook]

With 2 compact camera xenon tubes in series and a 1K, 10W dropper and the 2
camera trigger surfaces connected together to the existing trigger circuit,
it will reliably trigger the tubes to rather unstable continuous light ,
until I switch off , as 10W is not enough for continuous dropping.
I once triggered with the piezo gaslighter, proper trigger disconnected, but
didn't work the next few times.
The owner reported it would intermittently not work before giving up totally
, so I assumed it could not be a tube problem , well not gasifying anyway.
What can have gone wrong with the original tube ? Does the standing voltage
required to strike increase with age ?

 

[Sam Goldwasser]

onhttp://home.graffiti.net/diverse:graffiti.net/- Hide quoted text -

Let us inow what you find.


How do you test for lack of air in a xenon tube?
Putting a neon bulb and dropper over the trigger transformer gave plenty of
strike even in room lighting.
I've an old reserve piezo gas lighter that the metal grounding barrel on the
end falls off, ideal for testing this tube, but no flash over.
Trying to find a medium size xenon tube I have somewhere or will try with a
couple of copmpact camera xenon tubes or one removed from a xenon burglar
alarm flasher, both with some sort of droppers, later today

Basically that's it. Put 300-500 VDC across the tube and apply the output of
a Piezo lighter to trigger wire or reflector.

Or, if you have something like a helium-neon laser power supply or
neon sign transformer or oil burner ignition transformer, you can
apply its output through a ballst resistor to limit current across
the flashlamp. It should ionize.

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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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[Sam Goldwasser]

With 2 compact camera xenon tubes in series and a 1K, 10W dropper and the 2
camera trigger surfaces connected together to the existing trigger circuit,
it will reliably trigger the tubes to rather unstable continuous light ,
until I switch off , as 10W is not enough for continuous dropping.
I once triggered with the piezo gaslighter, proper trigger disconnected, but
didn't work the next few times.
The owner reported it would intermittently not work before giving up totally
, so I assumed it could not be a tube problem , well not gasifying anyway.
What can have gone wrong with the original tube ? Does the standing voltage
required to strike increase with age ?

Tubes can leak.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Important: Anything sent to the email address in the message header above is
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[N_Cook]

Tubes can leak.

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Could you have a very marginal leak over a couple of months leading to
intermittant problems ?
I would expect any leak to manifest itself as total failure in hours at the
most.

 

[N_Cook]

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?

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.

 

[James Sweet]

Could you have a very marginal leak over a couple of months leading to
intermittant problems ?
I would expect any leak to manifest itself as total failure in hours at
the
most.

Sure, you could have a leak small enough to take years to leak in enough air
to cause failure, it also may only leak under the stress of the tube firing.

 

[James Sweet]

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?

"Air" is a mixture of gasses, Xenon tubes are filled with Xenon gas, so no
real difference from that perspective, both the earth and the flash tube
have an atmosphere of gas.

I thought the sound was the shockwave created by the rapidly heated column
of gas expanding, haven't really researched it though.

 

[Jim Yanik]

"Air" is a mixture of gasses, Xenon tubes are filled with Xenon gas,
so no real difference from that perspective, both the earth and the
flash tube have an atmosphere of gas.

I thought the sound was the shockwave created by the rapidly heated
column of gas expanding, haven't really researched it though.

your shockwave theory appears correct;
http://en.wikipedia.org/wiki/Thunder

 

[N_Cook]

"Air" is a mixture of gasses, Xenon tubes are filled with Xenon gas, so no
real difference from that perspective, both the earth and the flash tube
have an atmosphere of gas.

I thought the sound was the shockwave created by the rapidly heated column
of gas expanding, haven't really researched it though.

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