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Re: Halo Blue?
In a message dated 96-04-13 00:17:11 EDT, Arturo de Carlo wrote:
>Dear Mr. Golin,
>First of all, can you tell me (or explain) what " F - Centers" are. My lack
>of English is killing me now.
(snip)
F-Centers are impurity centers in the phosphor crystal. The "F" is for a
German word I have forgotten and I did not look it up. It's in my Kittel,
will get it later.
(snip)
>I think that I can produce information about this matter for the list as I
>wrote over 40 pages A4 for my students only about the dry powder method (the
sponge and glass beads method) and the liquid (PHILIPS) suspencion technique
with
>all the formulas to produce your own liquid solution. As I think this is an
interested matter I will produce next week a global article about this matter
for the list.
(snip)
You do sound very informed on this subject, which is why I would like more
info.
>I don't have the intention that I can teach you something about this matter
>as you wrote me before that I have some misunderstandings about the sign
>industry that you told me that you know much better only from your practice.
>Being the owner of a neonshop for over 27 years, don't think that I have no
>knowledge from practice. Being a teacher I always try to teach my students
the
>theoretical knowledge first. As you think that proper theoretical knowledge
>is behind practice I think you are wrong, especially about the part you
replied
>to me that a neon transformer is not underloaded when there is not enough
>glasslength installed onto it. This transformer will burnout becouse of the
>higher primary current that is flowing to the primary coil and we here in
>Europe call a transformer loaded like that for sure overloaded. Only
overloaded
>electrical devices can burn-out and for neon transformers is that when there
>is not enough glass is installed. The fact you call that a underloaded
device
>(while the current is higher than nominal) is something I can not
understand.
>No way.
(snip)
There must be a way to avoid getting into a protracted argument on this
subject, and perhaps going on to a more productive subject. I didn't mean to
offend you but apparently I did not express myself cautiously or tactfully.
Clearly you are very well qualified and informed and have much to offer in
information on neon..
However, the claims you make on this particular subject, pertaining to
"underloading" transformers are just so completely contrary to every bit of
my experience and field study, I wonder actually if there may be some
difference in the construction of the transformers you use in Europe as
opposed to those used in the US. Is that possible? I just cannot avoid
reacting negatively to your comments on this based on what I am finding here.
In the US, we use a type of neon transformer made by Allanson in Canada, or
France in Tennesee, or Magnetek somewhere else here, known as "magnetic
shunt" where a laminated cross-piece "shorts out" the magnetic current in the
core when it reaches a maximum flux..This type of transformer approximates a
true current source. This prevents the current in the secondary winding (and
the primary winding as well) from runaway currents when a short load is used.
Is that the same type you use in Europe? I would assume so, but it's worth
checking.
This way, the maximum standard secondary current we can get with the wires
absolutely shorted out and no neon in the circuit is 30ma, for any standard
secondary voltage. (Forget about the higher 60, 120 etc. current models for
the moment) This is called, the short circuit current.(I hope I am not boring
anyone around here in the US, this is all standard knowledge but it's worth
checking if things are done the same way in Europe, as we are tempted to
assume.)
Okay, when the proper load is applied to the secondary output, the current
drops to 80%, or about 23ma. Now I grant you this is somewhat lower current,
but our transformers tolerate a great variation in the upper limits of this
spec and the loading is pretty flat on the upside. If I use a 12kV
transformer for a load which is normally calling for a 9kV, the result is
usually a significant increase in life, rather than a decrease, for reasons
of other factors involved in the design and life of the transformer. In my
field experiences, there is absolutely no question about this fact, based on
warranty statistics. This is a "conservative" design approach.
The greatest reasons are, 1) the problem that an overloaded transformer is a
much greater hazard than an underloaded one. An overloaded transformer, as
noted in Miller, Neon Techniques,(3rd edition), page 58, Fig 4.8(d) can
resonate with a high frequency at a voltage that is many times higher than
the rated spec.This figure shows an overloaded transformer with nanosecond
frequencies and as much as 30kV in spikes. No insulation, even pyrex glass,
can resist this kind of extreme high voltage for long. This 50-100% higher,
high frequency ringing voltage is far more destructive of the internal
windings and more quickly than any mere 20% maximum increases in current and
ohmic dissipation, because it easily breaks down the windings from
arcing-over within the coils. 2)Furthermore, it causes buzzing, high RFI and
breakdown of the neon tubes inside, and accelerates the process of neon gas
cleanup leading to an eventual higher resistance and ultimately an even more
overloaded circuit.3) An overloaded transformer easily results in wire
burnout and short-circuiting, a very dangerous and failing condition which
can cause fires.
This observation extends equally to the overloading caused by a metal conduit
enclosing a secondary wire. Non-metallic conduit invariably works better.
Perhaps we are dealing with slightly different transformer manufacturer and
design strategies. If in fact a transformer was designed more for sustaining
higher internal working voltages but for a weaker ohmic design, then we are
talking about two different animals. I can only tell you that my best and
most successful strategy for building the ultimately reliable neon sign
circuit involves making sure we underload the transformers rather than
overload, and it works like a charm every time.
(snip)
I will invite you to visit my course and factory as I have the strong
>feeling that you need more knowledge. If you are in the neighbourhood of
>Delft (near Rotterdam) I can prove to you that you are wrong. I have the
>facillities and precision laboratory instruments (property of the University
of Delft) to
>able to demonstrate to you your (to me) inconsequent lack of knowledge
>concerning overloaded transfomers.
Thanks for your invitation, but am presently not doing the international, or
even the domestic travel bit, unfortunately. Am homebound, an aging "homie"
as they say here, not rich enough to get away. Only passport I get lately is
AOL.
Love to see that global piece on phosphors.
Best Regards,
Jeff Golin
Neon Express
Mountain View, CA
(415)964-4110