In article ,
(DoN. Nichols) wrote:

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

[ ... ]

Well ... I just won the spare parts one on eBay for $24.95. As
I expected, there were no other bidders, given the *obviously* missing
parts.

Hope the meter is OK.

So do I. But if all else fails, it is at least a possible donor
for two more hairsprings. :-)

From the photo, it looks as though the faceplate is slightly
melted on the top right side -- but I can swap the faceplate from my
other one into that. It *may* be simply another JPEG artifact, as the
photo was rather heavily JPEGed. Or it could be dirt, or reflections.
It is right next to the missing special knob, in any case.

It looks like dirt plus JPEG to me. The nearby paint isn't blistered.



The special
knob has a transparent flange with a white dot of its own, and two DB
scales. The outer scale ranges from 50 to 140DB, and the inner one from
0 to -50. You start the measurements with both switches fully CW, and
you adjust one knob if the meter reads below 0 dB, or the other if it
reads above +10 dB. For calibration, you set both white dots pointing
straight up.

If you care to look at it, the eBay auction number is
7612826976.

Aside from the rather special switch knob missing, there is also
the clamshell case bottom/top and the linkage which joins them and
allows opening/closing without ever letting the parts separate.

All in all, a suitable boneyard denizen.


Good plan, though I had not done any filings generating work on
that bench. There is a shear on it, and a corner notching shear, and
a reloading press, none of which tend to generate filings.

But they do generate slivers.

Yes -- but have mostly been used on aluminum, which at least
tends to generate non-magnetic slivers. :-)

Yes, but still, a good vacuum cleaning and washdown is in order.

Agreed -- except a washdown is pretty difficult with so many
large tools bolted in place on that bench. At least all of them are
within my lifting ability -- unlike with the 24" DiAcro brake, for which
I would have to get the engine hoist. :-)

[ ... ]

Where was this?

U.S. Army Night Vision Labs (at that time -- it has since gone
through quite a few name changes -- once three in a single year. :-)
Location was (and still is Ft. Belvoir, VA.)

OK. But I bet they read the MIT Radiation Labs series (which laid out
the technical basis for radar, as developed in great secrecy during WW2).

Quite likely. Or encountered it in their college classes
recently enough so they still remembered it.

Before my time -- I had to read the old books.

I just got an isolation transformer (Tripp-Lite, 250 watt), so I can now
see the voltage waveforms in the AC powered strobe. After changing the
wiring in the isolation transformer: They had the output-side white
(neutral) hooked to the green (case), which makes sense for many
applications, but not for working on transformerless line-powered
electronics. However, Tripp-Lite made it easy to fix. All I had to do
was take the cover off, unbolt the grounding terminal, and insulate it
with some green heat-shrink tubing, yielding the desired floating output.

I'm seeing what I assume is interference from the main flash pulse
getting into the optical shaft-angle sensor. It appears harmless, but I
wonder what the path is, and what else it's getting into. The path is
not optical, and the effect occurs long after the trigger pulse has died
away.

Joe Gwinn

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

According to Joseph Gwinn :

[ ... ]

From the photo, it looks as though the faceplate is slightly
melted on the top right side -- but I can swap the faceplate from my
other one into that. It *may* be simply another JPEG artifact, as the
photo was rather heavily JPEGed. Or it could be dirt, or reflections.
It is right next to the missing special knob, in any case.

It looks like dirt plus JPEG to me. The nearby paint isn't blistered.

Agreed -- though the knob might have been. I'll know later when
it arrives -- if he ever gets in touch with us for shipping fees and the
address to send the payment to.

[ ... ]

If you care to look at it, the eBay auction number is
7612826976.

Aside from the rather special switch knob missing, there is also
the clamshell case bottom/top and the linkage which joins them and
allows opening/closing without ever letting the parts separate.

All in all, a suitable boneyard denizen.

Yep -- and a lot cheaper than having someone rebuild the
existing meter -- even before I lost the hairspring. :-)

I wonder if I'll ever spot that hairspring -- perhaps when
cleaning up somewhere. :-)

[ ... ]

OK. But I bet they read the MIT Radiation Labs series (which laid out
the technical basis for radar, as developed in great secrecy during WW2).

Quite likely. Or encountered it in their college classes
recently enough so they still remembered it.

Before my time -- I had to read the old books.

This was in the early to mid 1960s, IIRC, so those had a chance
of having encountered it in their classes.

I just got an isolation transformer (Tripp-Lite, 250 watt), so I can now
see the voltage waveforms in the AC powered strobe. After changing the
wiring in the isolation transformer: They had the output-side white
(neutral) hooked to the green (case), which makes sense for many
applications, but not for working on transformerless line-powered
electronics.

Agreed. I think that my isolation transformer is Triad, and
IIRC it has a rotary switch to make adjustments to the output voltage to
test equipment at slight over-voltage, and slight under-voltage.

However, Tripp-Lite made it easy to fix. All I had to do
was take the cover off, unbolt the grounding terminal, and insulate it
with some green heat-shrink tubing, yielding the desired floating output.

I'm seeing what I assume is interference from the main flash pulse
getting into the optical shaft-angle sensor. It appears harmless, but I
wonder what the path is, and what else it's getting into. The path is
not optical, and the effect occurs long after the trigger pulse has died
away.

O.K. *Which* AC-powered strobe? Not the Strobotach, since it
doesn't have an optical shaft angle sensor to start with. Have you
started working on something else while I wasn't looking?

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 :
In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :

[snip]

OK. But I bet they read the MIT Radiation Labs series (which laid out
the technical basis for radar, as developed in great secrecy during
WW2).

Quite likely. Or encountered it in their college classes
recently enough so they still remembered it.

Before my time -- I had to read the old books.

This was in the early to mid 1960s, IIRC, so those had a chance
of having encountered it in their classes.

I was in High School back then.


I just got an isolation transformer (Tripp-Lite, 250 watt), so I can now
see the voltage waveforms in the AC powered strobe. After changing the
wiring in the isolation transformer: They had the output-side white
(neutral) hooked to the green (case), which makes sense for many
applications, but not for working on transformerless line-powered
electronics.

Agreed. I think that my isolation transformer is Triad, and
IIRC it has a rotary switch to make adjustments to the output voltage to
test equipment at slight over-voltage, and slight under-voltage.

I haven't seen that. Does Triad still exist?

Anyway, I'll just use a variac at the input to vary the voltage.


However, Tripp-Lite made it easy to fix. All I had to do
was take the cover off, unbolt the grounding terminal, and insulate it
with some green heat-shrink tubing, yielding the desired floating output.

I'm seeing what I assume is interference from the main flash pulse
getting into the optical shaft-angle sensor. It appears harmless, but I
wonder what the path is, and what else it's getting into. The path is
not optical, and the effect occurs long after the trigger pulse has died
away.

O.K. *Which* AC-powered strobe? Not the Strobotach, since it
doesn't have an optical shaft angle sensor to start with. Have you
started working on something else while I wasn't looking?

No, it's the rotation-locked one I built for viewing a coil winder in
action. Without the transformer, I was flying blind because I couldn't
scope anything worthwhile in the line-connected circuitry.


Joe Gwinn

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

[ ... ]

Agreed. I think that my isolation transformer is Triad, and
IIRC it has a rotary switch to make adjustments to the output voltage to
test equipment at slight over-voltage, and slight under-voltage.

I haven't seen that. Does Triad still exist?

Sure. They have a web site which does not work properly with
Opera on a Sun workstation, but here is the URL:

http://www.triadmagnetics.com/Catalog/index.html

Mouser carries a lot of their transformers, but they don't stock
the isolation transformers so I can't pull down any images to see how
they compare to mine. Mine is old enough so it has only a 2-pin jack,
and a "cheater-cord" socket for power to the transformer -- which would
match what you would expect to find in a TV repair shop anyway. :-)

Anyway, I'll just use a variac at the input to vary the voltage.

O.K. That'll do nicely.

[ ... ]

O.K. *Which* AC-powered strobe? Not the Strobotach, since it
doesn't have an optical shaft angle sensor to start with. Have you
started working on something else while I wasn't looking?

No, it's the rotation-locked one I built for viewing a coil winder in
action. Without the transformer, I was flying blind because I couldn't
scope anything worthwhile in the line-connected circuitry.

O.K. I remember it now.

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 :
In article ,
(DoN. Nichols) wrote:

[ ... ]

Agreed. I think that my isolation transformer is Triad, and
IIRC it has a rotary switch to make adjustments to the output voltage to
test equipment at slight over-voltage, and slight under-voltage.

I haven't seen that. Does Triad still exist?

Sure. They have a web site which does not work properly with
Opera on a Sun workstation, but here is the URL:

http://www.triadmagnetics.com/Catalog/index.html

Mouser carries a lot of their transformers, but they don't stock
the isolation transformers so I can't pull down any images to see how
they compare to mine. Mine is old enough so it has only a 2-pin jack,
and a "cheater-cord" socket for power to the transformer -- which would
match what you would expect to find in a TV repair shop anyway. :-)

Yeah. I have seen them. But I wonder if it's really Triad, or a front
for Chinese stuff only. I bought a 3-winding "Stancor" audio
transformer that claimed to be able to handle 1,000 volts between any
two windings, but when I measured the capacitance between windings, it
was a few nanofarads between two of them, and 100 picofarads between
those two and the other. Hmm. I bet the first two are bifilar wound,
and will handle only a few hundred volts, whatever the magnet wire
insulation can handle. The datasheet also gave bandwidth and
distortion, but failed to specify the power level at which this
distortion was achieved. I emailed Stancor, and got an incomprehensible
reply: they confounded DC resistance with power, although they did admit
that perhaps the 1,000 volts wasn't for all windings. I never got a
reply to my email asking for clarification of the unclear parts.

Joe Gwinn

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

[ ... ]

http://www.triadmagnetics.com/Catalog/index.html

Mouser carries a lot of their transformers, but they don't stock
the isolation transformers so I can't pull down any images to see how
they compare to mine. Mine is old enough so it has only a 2-pin jack,
and a "cheater-cord" socket for power to the transformer -- which would
match what you would expect to find in a TV repair shop anyway. :-)

Yeah. I have seen them. But I wonder if it's really Triad, or a front
for Chinese stuff only.

I don't know -- but you might try digging through their web
site, if your browser is happier with it than mine is.

Of course -- my isolation transformer is old enough to predate
the supposed Chinese takeover. :-)

I bought a 3-winding "Stancor" audio
transformer that claimed to be able to handle 1,000 volts between any
two windings, but when I measured the capacitance between windings, it
was a few nanofarads between two of them, and 100 picofarads between
those two and the other. Hmm. I bet the first two are bifilar wound,
and will handle only a few hundred volts, whatever the magnet wire
insulation can handle. The datasheet also gave bandwidth and
distortion, but failed to specify the power level at which this
distortion was achieved. I emailed Stancor, and got an incomprehensible
reply: they confounded DC resistance with power, although they did admit
that perhaps the 1,000 volts wasn't for all windings. I never got a
reply to my email asking for clarification of the unclear parts.

It sounds as though you hit a marketing guy, not a real tech. :-)

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 :
In article ,
(DoN. Nichols) wrote:

[ ... ]

http://www.triadmagnetics.com/Catalog/index.html

Mouser carries a lot of their transformers, but they don't stock
the isolation transformers so I can't pull down any images to see how
they compare to mine. Mine is old enough so it has only a 2-pin jack,
and a "cheater-cord" socket for power to the transformer -- which would
match what you would expect to find in a TV repair shop anyway. :-)

Yeah. I have seen them. But I wonder if it's really Triad, or a front
for Chinese stuff only.

I don't know -- but you might try digging through their web
site, if your browser is happier with it than mine is.

It isn't, neither of them, but the problem is at Triad's end - the URLs
for the images are bogus.


Of course -- my isolation transformer is old enough to predate
the supposed Chinese takeover. :-)

I bought a 3-winding "Stancor" audio
transformer that claimed to be able to handle 1,000 volts between any
two windings, but when I measured the capacitance between windings, it
was a few nanofarads between two of them, and 100 picofarads between
those two and the other. Hmm. I bet the first two are bifilar wound,
and will handle only a few hundred volts, whatever the magnet wire
insulation can handle. The datasheet also gave bandwidth and
distortion, but failed to specify the power level at which this
distortion was achieved. I emailed Stancor, and got an incomprehensible
reply: they confounded DC resistance with power, although they did admit
that perhaps the 1,000 volts wasn't for all windings. I never got a
reply to my email asking for clarification of the unclear parts.

It sounds as though you hit a marketing guy, not a real tech. :-)

Yes, but I had the impression that they no longer had any engineers to
ask.

The experience makes me reluctant to use Stancor for anything, because I
can no longer trust their catalog descriptions. By the way, the audio
transformer works perfectly well. The only problem is that it isn't
even close to matching its description, or being what I needed, which
means that as a builder of one-off projects, every purchase would be a
drama. It was not always thus.

Joe Gwinn