The EG&G FX-6A xenon flashtube is used in the General radio Strobotac,
which is used to measure the speed of machines rotating at up to 25,000
rpm.

The FX-6As darken with age, and are hard to find.

FX-6A is an old EG&G product. The relevant part of EG&G was sold to
Perkin-Elmer (http://optoelectronics.perkinelmer.com), and P-E now makes
these flashlamps. I think that this is still done in Salem, Mass.

I talked to P-E today. The FX-6A is available for US $232.00 each for 1
to 10 units. FX-6 series are called "low cost strobes"; I don't want to
know what normal and high cost means.

They also sent me a FX-6A datasheet (well, max operating conditions):

Max energy per flash: 5 Joules.

Max average power: 7 watts.

Max anode voltage: 1000 Vdc.

Min anode voltage: 300 Vdc. (Typical will be ~600 Vdc.)

Max flash rate: 500 flashes per second (30,000 rpm).

Arc length is 7.9 mm. The trigger electrode (called the "sparker" is
near to the anode and cathode, inside the glass envelope. The required
voltage and energy was not documented.

Joe Gwinn

"Joseph Gwinn" wrote: (clip) The FX-6A is available for US $232.00 each
for 1 to 10 units. (clip)
^^^^^^^^^^^^^^^^
Holy crap! I have an old Strobotac that I bought years ago for $5 (I
think.) Care to make me an offer?

In article ,
"Leo Lichtman" wrote:

"Joseph Gwinn" wrote: (clip) The FX-6A is available for US $232.00 each
for 1 to 10 units. (clip)
^^^^^^^^^^^^^^^^
Holy crap! I have an old Strobotac that I bought years ago for $5 (I
think.) Care to make me an offer?

Ten dollars?

If I get a Strobotac, I'll be real motivated to do the engineering to
find and/or fit a substitute flashtube.

Joe Gwinn

According to Joseph Gwinn :
The EG&G FX-6A xenon flashtube is used in the General radio Strobotac,
which is used to measure the speed of machines rotating at up to 25,000
rpm.

The FX-6As darken with age, and are hard to find.

FX-6A is an old EG&G product. The relevant part of EG&G was sold to
Perkin-Elmer (http://optoelectronics.perkinelmer.com), and P-E now makes
these flashlamps. I think that this is still done in Salem, Mass.

Hmm ... where my wife was born (though not in the P-E plant. :-)

I talked to P-E today. The FX-6A is available for US $232.00 each for 1
to 10 units. FX-6 series are called "low cost strobes"; I don't want to
know what normal and high cost means.

####### ###
# # # # #### # # ###
# # # # # # # # ###
# # # # # ###### #
# # # # # # #
# # # # # # # # ###
####### #### #### # # ###

(The above should be viewed with a fixed-pitch font like Courier. If
you don't want to take the time to switch fonts, it simply says "Ouch!"
in *big* letters. :-)

That means that the batch of four which I won on an eBay auction
is worth $928.00.

They were made May 22 1975 according to the stamp on the box
endflap.

They also sent me a FX-6A datasheet (well, max operating conditions):

Max energy per flash: 5 Joules.

Max average power: 7 watts.

Max anode voltage: 1000 Vdc.

Min anode voltage: 300 Vdc. (Typical will be ~600 Vdc.)

Max flash rate: 500 flashes per second (30,000 rpm).

O.K. Which probably determines the choice of max RPM on the
Strobotac.

Arc length is 7.9 mm. The trigger electrode (called the "sparker" is
near to the anode and cathode, inside the glass envelope.

Actually -- there are five of them, One (pin 1) is very close to
one electrode (pin 9), and the remaining ones are equally spaced, with
the final one not being nearly as close to its electrode.

But this suggests that they fire at much lower voltages than the
typical trigger wrapped around the outside of the typical flashlamp.

The required
voltage and energy was not documented.

Hmm ... A pity that it is not documented. That could be one of
the factors which would make a normal flashlamp not suitable for the
circuit in the Strobotac.

Thanks for digging up this information.

If nothing else, it makes me feel better about spending a bit
over $125.00 for the batch of four of them -- and now I understand the
motivation of the winning bidder in the batch which I *lost* prior to
that. :-)

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
The EG&G FX-6A xenon flashtube is used in the General radio Strobotac,
which is used to measure the speed of machines rotating at up to 25,000
rpm.

The FX-6As darken with age, and are hard to find.

FX-6A is an old EG&G product. The relevant part of EG&G was sold to
Perkin-Elmer (http://optoelectronics.perkinelmer.com), and P-E now makes
these flashlamps. I think that this is still done in Salem, Mass.

Hmm ... where my wife was born (though not in the P-E plant. :-)

I talked to P-E today. The FX-6A is available for US $232.00 each for 1
to 10 units. FX-6 series are called "low cost strobes"; I don't want to
know what normal and high cost means.

####### ###
# # # # #### # # ###
# # # # # # # # ###
# # # # # ###### #
# # # # # # #
# # # # # # # # ###
####### #### #### # # ###

(The above should be viewed with a fixed-pitch font like Courier. If
you don't want to take the time to switch fonts, it simply says "Ouch!"
in *big* letters. :-)

That means that the batch of four which I won on an eBay auction
is worth $928.00.

They were made May 22 1975 according to the stamp on the box
endflap.

I wonder if P-E is actually making the tubes these days, or selling new
old stock one tube at a time.

I also wonder if the Russians have duplicated the FX-6A. They still
make pretty good vacuum tubes, and I would not be surprised if there was
a Soviet-era copy of the Strobotac.


They also sent me a FX-6A datasheet (well, max operating conditions):

Max energy per flash: 5 Joules.

Max average power: 7 watts.

Max anode voltage: 1000 Vdc.

Min anode voltage: 300 Vdc. (Typical will be ~600 Vdc.)

Max flash rate: 500 flashes per second (30,000 rpm).

O.K. Which probably determines the choice of max RPM on the
Strobotac.

Yes.


Arc length is 7.9 mm. The trigger electrode (called the "sparker" is
near to the anode and cathode, inside the glass envelope.

Actually -- there are five of them, One (pin 1) is very close to
one electrode (pin 9), and the remaining ones are equally spaced, with
the final one not being nearly as close to its electrode.

Apparently, all but the one designated as the sparker are used only as
probes. No idea what is being probed for, or why.

Pin# - Use
1-3 - probe when required
4 - Anode (ie, positive)
5 - open
6 - probe when required
7 - Probe (no "when required")
8 - Sparker (will most likely be positive wrt the cathode)
9 - Cathode (ie, negative)


But this suggests that they fire at much lower voltages than the
typical trigger wrapped around the outside of the typical flashlamp.

Yes, by a factor. The current Series 1100 tubes should give us the
needed voltage range range, although the 1100s only go to 300 Hz.


The required voltage and energy was not documented.

Hmm ... A pity that it is not documented. That could be one of
the factors which would make a normal flashlamp not suitable for the
circuit in the Strobotac.

One clue is that the max anode voltage is 1,000 volts. The sparker
voltage will be in that range, as the sparker is simply another nearby
electrode, albeit one not designed to handle the full flash energy.
Typically, an internal trigger takes less than the full holdoff voltage.

I recall that the flash capacitors are charged to 600 volts; don't know
where I got that tidbit.

A little reverse engineering is in order. Can you measure the trigger
capacitor voltage and capacitance in your Strobotac? This will tell us
the needed trigger energy.

Does anyone have a circuit diagram?


Thanks for digging up this information.

If nothing else, it makes me feel better about spending a bit
over $125.00 for the batch of four of them -- and now I understand the
motivation of the winning bidder in the batch which I *lost* prior to
that. :-)

Yes.

I do see some current-production P-E flashlamps rated for 1,000 Hz, so
some kind of retrofit seems possible, although one may also need to
either replace or augment the trigger transformer.

Joe Gwinn

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

They were made May 22 1975 according to the stamp on the box
endflap.

I wonder if P-E is actually making the tubes these days, or selling new
old stock one tube at a time.

A good question. I wonder whether they have re-boxed them if
selling NOS -- or whether the boxes still say EG&G? :-)

I also wonder if the Russians have duplicated the FX-6A. They still
make pretty good vacuum tubes, and I would not be surprised if there was
a Soviet-era copy of the Strobotac.

That is possible.

They also sent me a FX-6A datasheet (well, max operating conditions):

Max energy per flash: 5 Joules.

Max average power: 7 watts.

Max anode voltage: 1000 Vdc.

Min anode voltage: 300 Vdc. (Typical will be ~600 Vdc.)

Max flash rate: 500 flashes per second (30,000 rpm).

O.K. Which probably determines the choice of max RPM on the
Strobotac.

Yes.


Arc length is 7.9 mm. The trigger electrode (called the "sparker" is
near to the anode and cathode, inside the glass envelope.

Actually -- there are five of them, One (pin 1) is very close to
one electrode (pin 9), and the remaining ones are equally spaced, with
the final one not being nearly as close to its electrode.

Apparently, all but the one designated as the sparker are used only as
probes. No idea what is being probed for, or why.

Pin# - Use
1-3 - probe when required
4 - Anode (ie, positive)
5 - open
6 - probe when required
7 - Probe (no "when required")
8 - Sparker (will most likely be positive wrt the cathode)
9 - Cathode (ie, negative)

O.K. My examination of the device shows that only one is
actually driven directly -- but the others appear to be capacitively
coupled through the ribbon cable. I haven't pulled the lamp socket out,
but based on the layout of the ribbon cable, I would expect the
"sparker" to be the middle of the set.

But this suggests that they fire at much lower voltages than the
typical trigger wrapped around the outside of the typical flashlamp.

Yes, by a factor. The current Series 1100 tubes should give us the
needed voltage range range, although the 1100s only go to 300 Hz.

O.K. Good for slow rotating devices -- but not the top end.

The required voltage and energy was not documented.

Hmm ... A pity that it is not documented. That could be one of
the factors which would make a normal flashlamp not suitable for the
circuit in the Strobotac.

One clue is that the max anode voltage is 1,000 volts. The sparker
voltage will be in that range, as the sparker is simply another nearby
electrode, albeit one not designed to handle the full flash energy.
Typically, an internal trigger takes less than the full holdoff voltage.

I recall that the flash capacitors are charged to 600 volts; don't know
where I got that tidbit.

Hmm ... the three main flash capacitors in the StroboTac are all
rated at 1000 VDC -- and selected by the range switch.

A little reverse engineering is in order. Can you measure the trigger
capacitor voltage and capacitance in your Strobotac? This will tell us
the needed trigger energy.

It is pretty densely packed. The trigger transformer seems to
be in a potted brick -- and I *think* that the capacitor is included in
that brick.

Does anyone have a circuit diagram?

Not I. One of the things that I looked for while I had it open
was a circuit diagram pasted inside the case. No such luck.

O.K. A google Search lead me to a PDF file of a manual for the
1538-A Strobotac -- as slightly later version.

This says that the tube operates at 800-1000 VDC, and the
trigger is 5000 V.

O.K. I've found some schematics -- and this one is solid-state,
while the previous one (which I have) is tube based -- as shown by
another posting this evening on this newsgroup -- so I won't duplicate
it here.

Go to

http://www.ietlabs.com/pdf/Manuals/

and you will find manuals for both the 1538-A and the 1531-A/B, among
others.

I've just bookmarked that -- and gotten manuals for several
things which I have.

[ ... ]

I do see some current-production P-E flashlamps rated for 1,000 Hz, so
some kind of retrofit seems possible, although one may also need to
either replace or augment the trigger transformer.

O.K. Good luck with those.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Here is something useful

http://members.misty.com/don/samflash.html



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:


Arc length is 7.9 mm. The trigger electrode (called the "sparker" is
near to the anode and cathode, inside the glass envelope.

Actually -- there are five of them, One (pin 1) is very close to
one electrode (pin 9), and the remaining ones are equally spaced, with
the final one not being nearly as close to its electrode.

Apparently, all but the one designated as the sparker are used only as
probes. No idea what is being probed for, or why.

Pin# - Use
1-3 - probe when required
4 - Anode (ie, positive)
5 - open
6 - probe when required
7 - Probe (no "when required")
8 - Sparker (will most likely be positive wrt the cathode)
9 - Cathode (ie, negative)

O.K. My examination of the device shows that only one is
actually driven directly -- but the others appear to be capacitively
coupled through the ribbon cable. I haven't pulled the lamp socket out,
but based on the layout of the ribbon cable, I would expect the
"sparker" to be the middle of the set.

The circuit drawings seem to say that all are driven by a 5 KV pulse
through 22 picofarad capacitors, one per line.


But this suggests that they fire at much lower voltages than the
typical trigger wrapped around the outside of the typical flashlamp.

Yes, by a factor. The current Series 1100 tubes should give us the
needed voltage range range, although the 1100s only go to 300 Hz.

O.K. Good for slow rotating devices -- but not the top end.

The required voltage and energy was not documented.

Hmm ... A pity that it is not documented. That could be one of
the factors which would make a normal flashlamp not suitable for the
circuit in the Strobotac.

One clue is that the max anode voltage is 1,000 volts. The sparker
voltage will be in that range, as the sparker is simply another nearby
electrode, albeit one not designed to handle the full flash energy.
Typically, an internal trigger takes less than the full holdoff voltage.

I recall that the flash capacitors are charged to 600 volts; don't know
where I got that tidbit.

Hmm ... the three main flash capacitors in the StroboTac are all
rated at 1000 VDC -- and selected by the range switch.

It may be 800 volts. It seems to depend on the model. It's easy to
achieve 600 volts with a voltage quadrupler, without a HV transformer.


A little reverse engineering is in order. Can you measure the trigger
capacitor voltage and capacitance in your Strobotac? This will tell us
the needed trigger energy.

It is pretty densely packed. The trigger transformer seems to
be in a potted brick -- and I *think* that the capacitor is included in
that brick.

It is, according to the circuit diagrams.


Does anyone have a circuit diagram?

Not I. One of the things that I looked for while I had it open
was a circuit diagram pasted inside the case. No such luck.

O.K. A google Search lead me to a PDF file of a manual for the
1538-A Strobotac -- as slightly later version.

This says that the tube operates at 800-1000 VDC, and the
trigger is 5000 V.

O.K. I've found some schematics -- and this one is solid-state,
while the previous one (which I have) is tube based -- as shown by
another posting this evening on this newsgroup -- so I won't duplicate
it here.

Go to

http://www.ietlabs.com/pdf/Manuals/

and you will find manuals for both the 1538-A and the 1531-A/B, among
others.

I've just bookmarked that -- and gotten manuals for several
things which I have.

Bingo! Of course. I got them. Thanks.


I do see some current-production P-E flashlamps rated for 1,000 Hz, so
some kind of retrofit seems possible, although one may also need to
either replace or augment the trigger transformer.

O.K. Good luck with those.

I may also have a way to make an ordinary flashtube work far above it's
normal flash rate, based on tricks used to get far above 25,000 plashes
per minute.

Joe Gwinn

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

Apparently, all but the one designated as the sparker are used only as
probes. No idea what is being probed for, or why.

Pin# - Use
1-3 - probe when required
4 - Anode (ie, positive)
5 - open
6 - probe when required
7 - Probe (no "when required")
8 - Sparker (will most likely be positive wrt the cathode)
9 - Cathode (ie, negative)

And based on the manuals (discussed below) pins 1, 4, and 9 are
actually used. (1 being one of the "probes", 4 being the anode, and 9
being the cathode). All other "probes" are only getting signal
capacitively coupled by the adjacent runs in the ribbon cable (perhaps
1-1/2" long).

O.K. My examination of the device shows that only one is
actually driven directly -- but the others appear to be capacitively
coupled through the ribbon cable. I haven't pulled the lamp socket out,
but based on the layout of the ribbon cable, I would expect the
"sparker" to be the middle of the set.

The circuit drawings seem to say that all are driven by a 5 KV pulse
through 22 picofarad capacitors, one per line.

If so, the "capacitors" are in reality parasitic capacitance
in that ribbon cable, as only the one is actually connected to anything,
at least on my 1531-A. The photo (Figure 4-10, page 26) in the manual
for the 1538-A shows the same construction, FWIW.

[ ... ]

One clue is that the max anode voltage is 1,000 volts. The sparker
voltage will be in that range, as the sparker is simply another nearby
electrode, albeit one not designed to handle the full flash energy.
Typically, an internal trigger takes less than the full holdoff voltage.

I recall that the flash capacitors are charged to 600 volts; don't know
where I got that tidbit.

Hmm ... the three main flash capacitors in the StroboTac are all
rated at 1000 VDC -- and selected by the range switch.

It may be 800 volts. It seems to depend on the model. It's easy to
achieve 600 volts with a voltage quadrupler, without a HV transformer.

Looking at the full schematic for the 1531-A, The anode and
cathode are respectively connected to +400V and -400V (developed from a
310V winding on the power transformer in the 1531-A), and in the 1538-A,
there appears to be a one-shot triggering the primary of a small
transformer as a DC-DC converter, which gives +800V.

I don't find complete schematics for the 1538-A, though the
1531-A has the complete set. Both have the ghost views of the PC
traces. And, apparently, IET still services (and supplies parts) for
both models.

I wonder how much of GR's line IET took over? Or was it just a
case of renaming the company for whatever reason?

[ ... ]

It is pretty densely packed. The trigger transformer seems to
be in a potted brick -- and I *think* that the capacitor is included in
that brick.

It is, according to the circuit diagrams.

Making it rather difficult to check out.

Does anyone have a circuit diagram?

[ ... ]

O.K. I've found some schematics -- and this one is solid-state,
while the previous one (which I have) is tube based -- as shown by
another posting this evening on this newsgroup -- so I won't duplicate
it here.

Go to

http://www.ietlabs.com/pdf/Manuals/

and you will find manuals for both the 1538-A and the 1531-A/B, among
others.

I've just bookmarked that -- and gotten manuals for several
things which I have.

Bingo! Of course. I got them. Thanks.

Great!


I do see some current-production P-E flashlamps rated for 1,000 Hz, so
some kind of retrofit seems possible, although one may also need to
either replace or augment the trigger transformer.

O.K. Good luck with those.

I may also have a way to make an ordinary flashtube work far above it's
normal flash rate, based on tricks used to get far above 25,000 plashes
per minute.

I see that the FX-7A is suggested as the current replacement
lamp. I wonder what the prices are for that one?

Enjoy
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Joseph Gwinn wrote:
The EG&G FX-6A xenon flashtube is used in the General radio Strobotac,
which is used to measure the speed of machines rotating at up to 25,000
rpm.

The FX-6As darken with age, and are hard to find.



Thats an outrageous price! - depending on the mechanical fittings, it
SHOULD be possible to use a "standard" flash tube (their about $5 here)
- you would need to get a trigger transformer and add a wire wrapped
around the body to trigger them, but hey.....worth a try - might be
other considerations, would need to dig out the data sheets and see.

Andrew VK3BFA.

http://www.jaycar.com.au/products_uploaded/SL2692.pdf

is a link to the typical tube I was talking about.

On 18 Apr 2006 02:29:55 -0700, "Andrew VK3BFA"
wrote:

http://www.jaycar.com.au/products_uploaded/SL2692.pdf

is a link to the typical tube I was talking about.

Looks like the ones used for dance-floor lighting- have you tried a
stage equipment shop?

-Carl

In article ,
Carl Byrns wrote:

On 18 Apr 2006 02:29:55 -0700, "Andrew VK3BFA"
wrote:

http://www.jaycar.com.au/products_uploaded/SL2692.pdf

is a link to the typical tube I was talking about.

Looks like the ones used for dance-floor lighting- have you tried a
stage equipment shop?

I would have thought dance-floor strobes would be far slower and far
more powerful than a Strobotac.

One use of the FX-6A that I've found is automotive wheel balancers that
were made by Balance Technology Inc (BTI) and competitors. Wonder what
they use these days; I'm sure that won't stand still for $230 per tube.

Joe Gwinn

"Joseph Gwinn" wrote in message
...
In article ,
Carl Byrns wrote:

On 18 Apr 2006 02:29:55 -0700, "Andrew VK3BFA"
wrote:

http://www.jaycar.com.au/products_uploaded/SL2692.pdf

is a link to the typical tube I was talking about.

Looks like the ones used for dance-floor lighting- have you tried a
stage equipment shop?

I would have thought dance-floor strobes would be far slower and far
more powerful than a Strobotac.

One use of the FX-6A that I've found is automotive wheel balancers that
were made by Balance Technology Inc (BTI) and competitors. Wonder what
they use these days; I'm sure that won't stand still for $230 per tube.


Anyone try uaing one of the new super bright white LEDs for a strobe?

In article .com,
"Andrew VK3BFA" wrote:

http://www.jaycar.com.au/products_uploaded/SL2692.pdf

is a link to the typical tube I was talking about.

Thanks. Who is the maker? Do they have application notes and more
complete datasheets?

Joe Gwinn

Joseph Gwinn wrote:
In article .com,
"Andrew VK3BFA" wrote:

http://www.jaycar.com.au/products_uploaded/SL2692.pdf

is a link to the typical tube I was talking about.

Thanks. Who is the maker? Do they have application notes and more
complete datasheets?

Joe Gwinn

Hi Joe,
what you see is what you get - the data sheet was all that was on a
local retailers website. probably, asuming your in the US, that Digikey
or Mouser would have similar ones - perhaps they would have more data.
The max strobe rate - no idea, but I cant imagine that the listed tube
in the original post is the ONLY one suitable in the world.

Its a basis for experimentation - might work, might not, Relatively
cheap and easy to lash up - if it works, a nice bit of test gear back
on the road, if it doesnt - well, youve blown 10 bucks and a bit of
time..... Trigger transformers are also available, about 2 dollars.

I am a working technicain, not an engineer - cant give you voluminous
theory on the application, I use the "suck it and see"
approach........sometimes works, sometimes a spectacular failure. But I
do get enough oddball electronic things like this working to make a
(precarious) living.......the high value or rare device thats worth
putting a few hours of experimentation into before they go to the
dumpster....

Andrew VK3BFA.

According to Andrew VK3BFA :

Joseph Gwinn wrote:
In article .com,
"Andrew VK3BFA" wrote:

http://www.jaycar.com.au/products_uploaded/SL2692.pdf

is a link to the typical tube I was talking about.

[ ... ]

what you see is what you get - the data sheet was all that was on a
local retailers website. probably, asuming your in the US, that Digikey
or Mouser would have similar ones - perhaps they would have more data.
The max strobe rate - no idea, but I cant imagine that the listed tube
in the original post is the ONLY one suitable in the world.

There is also the FX-7 -- which appears to have a larger
envelope size, but otherwise be similar, so it might work, except for
not fitting the reflector. And I'll bet that it is at least as
expensive as the FX-6A.

Its a basis for experimentation - might work, might not, Relatively
cheap and easy to lash up - if it works, a nice bit of test gear back
on the road, if it doesnt - well, youve blown 10 bucks and a bit of
time..... Trigger transformers are also available, about 2 dollars.

Yes -- but these are quite unlike the FX-6A.

The FX-6A is in a stubby 9-pin miniature tube base.

It has the two main electrodes allocated to two of those pins.

It has *five* *internal* trigger electrodes connected to five of
the remaining pins -- fine wires reaching in to points along the arc
path, and all electrically independent.

The Strobotac has a 7-conductor ribbon cable going from the
electronics box to the pivoted stem which contains the 9-pin socket for
the flash tube, and over which the neck of the reflector fits. (This
rather limits the maximum dimensions of the tube to ones no larger in
some dimension than the diameter of a 9-pin miniature tube.

The reflector is designed so the arc length (about 1/2" long) is
in the focus of the reflector.

The internal flash triggers operate (presumably) at a much lower
voltage than external triggers.

The fact that a separate wire is brought out to each suggests
that each has a unique voltage applied to direct the arc along the
intended path.

I am a working technicain, not an engineer - cant give you voluminous
theory on the application, I use the "suck it and see"
approach........sometimes works, sometimes a spectacular failure.

Including possibly an induced failure to the trigger circuits in
the StroboTac in this case.

While I have the four remaining unused lamps, plus the one in
pretty good condition, and one rather darkened from use, I intend to use
it as it was designed.

If those ever are all expended -- *then* I will try retrofitting
some newer flashlamp. But I think that not too many of those are
designed to survive 27K flashes/minute. :-) And I'm not sure about the
trigger transformer, either.

O.K. You finally got my interest piqued sufficiently, so I just
pulled it out of its case:

1) It is old enough to be tube driven, not solid state. A 5965
and a 5727. This suggests that the trigger circuit is not as
fragile as I at first feared.

2) Looking at the ribbon cable end inside the box, the flashlamp
main terminals are the end-most ribbon cable leads, the only
trigger connection is for the center one, feeding the centermost
trigger electrode which suggests that the ribbon cable acts as a
capacitive voltage divider to couple signal to the remaining
trigger electrodes.

3) The trigger transformer is a potted brick, about
1-1/2 x 2-1/4 x 3/4"

4) The main capacitor for the highest flash level is 1.15 uF at
1000 VDC. The smallest is 0.47 uF, also at 1000 VDC. The
middle one is 0.22 uF, again at 1000 VDC. They are all marked
"Vicofilm Capacitor" from "Industrial Condenser Company".

5) It does have *some* solid state devices -- a bridge of top-hat
rectifiers. :-)

6) There is also a three-section electrolytic. 50 uF, 25 uF, and
25 uF at 450VDC.

7) The speed pot is one of General Radio's special precision wirewound
pots, though there are four Allen-Bradley sealed pots scattered
around the rest of the circuit.

8) And, of course, it has a custom power transformer, with no
useful markings.

9) Two slow-blow (MDL) fuses (1/2 A, 250V) in clips on one of the
circuit boards.

10) One NE-2 lamp between two upright braces, secured by a
heat-shrink band as a vibration seal. It is presumably a
voltage reference, as there is no way for the light to get out,
and the pilot light for the speed scales is a bayonet-base
incandescent pilot light. (Another NE-2 is used as part of the
calibration system -- it is visible through a window in the
front panel, and you set the speed pot to specific speeds, and
tune the front-accesible pots for lowest brighten/dim rate in
the lamp.

11) The date codes on components seem to be in the 1967-1968 range.

Don't expect me to attempt to trace the circuit -- it is General
Radio's quality construction of the period, with single-sided circuit
boards, but it is too dense a construction for me to bother without
serious need.

But I
do get enough oddball electronic things like this working to make a
(precarious) living.......the high value or rare device thats worth
putting a few hours of experimentation into before they go to the
dumpster....

Understood. But at present, it is cheaper to buy more
StroboTacs on eBay than to buy new lamps. So -- as long as the lamps
with those are in good shape, you could get one, sell the lamp back on
eBay, and experiment with your own StroboTac.

FWIW -- the energy per flash is in three ranges, corresponding
to three flash rate ranges, so you don't overheat the lamp and burn it
out too rapidly.

Enjoy,
DoN.
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