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Re: More HBT info for Doug

I bought a 100' spool of 10-gauge a little while ago. Problem is, unless I
have a
LOT of secondary windings to go with it, the inductance will be really low and
it'll waste a huge amount of energy in hysteresis losses. I'm going to try
to put
as many secondary windings on as I can, maybe 6400 or 10000 if I'm lucky
and can
rip open some unused transformers.

Another question: if I were to put in an external inductive current
limiter, would
that be a big power loss (as in would I be losing a large fraction of the
power I
put in to the limiter, rather than my coil)? Is a variac a better way to go
(if
current starts to get too high, turn down the voltage), or is doing
something like
that unsafe?

Tesla List wrote:

> Original Poster: RWB355-at-aol-dot-com
>
>  Original Poster: Doug Brunner <dabrunner-at-earthlink-dot-net>
>
>  Question: what do you mean by "shunted" and "non shunted"?
>
> Hi Doug,
>
> The difference between a shunted and a non shunted tranny is very simple.
The
> non shunted just has a simple iron core. Usually they are a mix of Eīs and
> Iīs, altho there are different shapes out there. My xformer core (I plan to
> use for my HBT) is made of two Eīs, one being backward. One outer leg of
each
> E is shorter and the middle leg is cut at an angle, so they fit nicely front
> to front to form the core. The lamination of the core (instead of just a
chunk
> of iron) reduce the eddy current losses in the core (considerably).
>
> A shunted xformer has a set of laminations inserted 90° to the real core.
This
> limits the magnetic flux that can pass through the core, limiting the max
> current. If you short one of these transformers the voltage breaks down and
> the current can only go as high as the shunt (90° lams) allows it to go.
This
> transformer can be shorted all day and night without harm. The reason NSTīs
> are limited in this manner is very easy to explain. The neon tube has a
> positiv U/I curve. This means the more volts you put put in, the higher the
> current will go. If the NST werenīt current limited either the tube or the
> tranny would go up in smoke. The neon tube only needs the 15000 volts to
> ionize the gas, so that it can start to conduct. After that the NSTīs
voltage
> breaks down to about 600-1kV.
>
> Get the "real" (iron core) NST before they die out and start to get really
> expensive.
>
> For this reason newer signs are starting to use a semiconductor xformer.
They
> ionize the gas per thyristor kick and (after the sign is started) they run a
> frequency controlled switching psu providing the necessary 600-1000 volts to
> keep the sign lit up. They are frequency controlled for two reasons:
>
> 1.) A HF PSU is smaller and cheaper to build.
> 2.) A change in frequency changes the output voltage. Voila, you now have a
> dimmable neon sign !! (Which in do course lets the companies charge more for
> something that is cheaper to build. But itīs got any "extra", so the end
> customer has to pay more for it.)
>
> You can look at the magnetic shunt like a series (with the primary winding)
> inductor which some of us Teslanians use externally on pole pigs or other
non
> current limited xformers. If you short a pig it will either burn out and
pull
> your whole neigherhood down in the process or your circuit breakers
> (hopefully) will cut out. A 10kVA pig is NOT limited (talking about max
input
> amps here) to 10KVA!!
>
> I have to agree with Malcom about your core going into saturation without
even
> getting near your 120 volt input. To make a wild guess I would say your core
> will saturate somewhere between 35-60 volts. This means if you go above this
> voltage you are not going to get an incease in your output voltage thatīs
> anywhere near being linear. Actually an increase in input volts wonīt be
> noticeable in your output.
> The "extra" energy will just be wasted in core/wire heating. Nothing you
> really want, building a xformer.
>
> If I were you I would seriously think about using larger wire gauges and
only
> one wire (instead of 5). The larger wire size isnīt going to be more
expensive
> than five times the smaller diameter length. If this WAS the way to go,
donīt
> you think transformer makers would do this?
>
>  As someone else stated a while ago there is no black magic in winding
> transformers. There is a good deal of know how behind the core construction,
> but the winding just boils down to cost effectiveness, which is something to
> consider when you are making thousands of xformers, but when you are just
> winding one or two.
>
> My advice is if really, absolutely, must want, have to do, go your way then
> take Erikīs advice and start with the primary. Wind it. Take a variac and an
> ampere meter and measure the current as you ramp up the voltage. Iīm sure
you
> WILL then see why itīs not the way to go.
>
> Coiler greets and good luck from germany,
> Reinhard



--
           --Mr. Postman (Doug Brunner)
                <dabrunner-at-earthlink-dot-net>