John Byrns wrote:

OK, I see we are going in opposite directions on the coupling effect.
If the coupling were perfect when the core is not saturated, then the
light would be as bright as it could get due to the bucking effect of
the two windings.

Right - up to the "as it could get" with the core NOT saturated - then
the coupling is good - the windings buck - bulb dim.


When the transformer becomes saturated decreasing the
coupling, the brightness would have nowhere to go but down due the
residual inductance remaining in the two coils.

This is where you go off track - when the core saturates two things
happen - the inductance of the coils drops through the floor - less
inductance - higher current. The coupling also starts to fail as well -
so the bucking effect also decreases - bulb brighter...


News Flash, I am really liking the theory I advanced a few messages ago
that the "transformer" is not wound like an ordinary transformer, but
instead has one of the secondaries wound on each outside leg of the
E-core.

Not news - this would be common for a saturable reactor.

The reason I am really liking this theory now is that I looked up the
service data for the General Electric E-155 which has the similar
Colorama tuning system, and the "transformer" is constructed exactly as
I speculated in my earlier message. If the S-W "transformer" is built
the same way then it is a whole new ball game.

Why? If in fact (as I've postulated most recently) that reactance is
indeed the greater control factor - then whether one coil of the two is
reversed or not would only effect the linearity of the control, not that
it works. I looked up a few site - and found a couple interesting ones...

http://www.allaboutcircuits.com/vol_2/chpt_9/7.html

Down towards the bottom of the page - just above the Scott-T. Notice
that in the final example - they reverse one of the two control windings
- the same thing would be accomplished by leaving the control windings
in phase and reversing the the load winding... Here they use two
reactors to accomplish symmetry - here is a way to do it with one:

http://www.tpub.com/content/neets/14.../14180_137.htm
note that this is the first of several pages - you'll have to page
through them to get to the main point. Notice that by the time they get
to the three legged configuration - (and torrids) - the load windings
are opposed to provide symmetry.

Again not knowing the construction of the S/W transformer leaves some
guessing - but as I noted before - if all three windings are wound on a
C form - then bucking may be a significant part of the control
equation - if three legged on an E core (I doubt torrids were in use
back then) - then bucking would not be significant (as that coupling
would be minor compared to the reactance change).

best regards...
--
randy guttery

A Tender Tale - a page dedicated to those Ships and Crews
so vital to the United States Silent Service:
http://tendertale.com

Randy or Sherry Guttery wrote:

a bunch of stuff...

Let me add a point... when I originally looked at the schematic - the
saturable reactor was drawn as a transformer - though it didn't take
long to figure out that it had to be a form of saturable reactor rather
than a transformer... (being an early schematic, I doubt the "standard"
for indicating saturable reactors had been established, and certainly
not yet in common use).

That only leaves figuring out whether the S/W is a two or three legged
configuration (are the two load windings on the same leg). As noted - a
picture might tell a lot. Also - note that the GE version is a fully
buffered (isolated) and driven system - while the S/W's system is part
of the RF / IF B+... the differences make a significant impact on how
the two circuits act (and interact)...

best regards...
--
randy guttery

A Tender Tale - a page dedicated to those Ships and Crews
so vital to the United States Silent Service:
http://tendertale.com

In article ,
Randy or Sherry Guttery wrote:

Randy or Sherry Guttery wrote:

a bunch of stuff...

Let me add a point... when I originally looked at the schematic - the
saturable reactor was drawn as a transformer - though it didn't take
long to figure out that it had to be a form of saturable reactor rather
than a transformer... (being an early schematic, I doubt the "standard"
for indicating saturable reactors had been established, and certainly
not yet in common use).

That only leaves figuring out whether the S/W is a two or three legged
configuration (are the two load windings on the same leg). As noted - a
picture might tell a lot.

Dave has now posted a picture, it appears to be a three leg core with
all three windings on the central leg.

Also - note that the GE version is a fully
buffered (isolated) and driven system - while the S/W's system is part
of the RF / IF B+... the differences make a significant impact on how
the two circuits act (and interact)...

I don't see how the "buffer" in the GE circuit makes any difference at
all, S-W simply make the RF and IF tubes do double duty, serving as a
"buffer" in addition to their normal functions. The buffering aspect
seems to work in an identical fashion to the dedicated "buffer" in the
GE radio.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

John Byrns wrote:


I don't see how the "buffer" in the GE circuit makes any difference at
all, S-W simply make the RF and IF tubes do double duty, serving as a
"buffer" in addition to their normal functions. The buffering aspect
seems to work in an identical fashion to the dedicated "buffer" in the
GE radio.

There is no need for the filter caps on the primary in the GE version -
as the tube eliminates any posibility of ripple from the reactor getting
into the B+ - as is the case with the S/W. Also by using a tube - GE
can independantly control the saturation curve, direction (inverted from
b+, for instance) or by using agc directly, etc., etc. Lots of
variables introduced by using that buffer tube.

best regards...
--
randy guttery

A Tender Tale - a page dedicated to those Ships and Crews
so vital to the United States Silent Service:
http://tendertale.com

In article Rknai.22481$dy1.19814@bigfe9,
Randy or Sherry Guttery wrote:

John Byrns wrote:


I don't see how the "buffer" in the GE circuit makes any difference at
all, S-W simply make the RF and IF tubes do double duty, serving as a
"buffer" in addition to their normal functions. The buffering aspect
seems to work in an identical fashion to the dedicated "buffer" in the
GE radio.

There is no need for the filter caps on the primary in the GE version -
as the tube eliminates any posibility of ripple from the reactor getting
into the B+ - as is the case with the S/W. Also by using a tube - GE
can independantly control the saturation curve, direction (inverted from
b+, for instance) or by using agc directly, etc., etc. Lots of
variables introduced by using that buffer tube.

I don't see how any of that makes any difference in the basic operation
of the circuit, S-W simply got a little more work out of their tubes.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

In article ,
Randy or Sherry Guttery wrote:

John Byrns wrote:

OK, I see we are going in opposite directions on the coupling effect.
If the coupling were perfect when the core is not saturated, then the
light would be as bright as it could get due to the bucking effect of
the two windings.

Right - up to the "as it could get" with the core NOT saturated - then
the coupling is good - the windings buck - bulb dim.

Either we don't mean the same thing by "buck", or we will each have to
go our own way.

When the transformer becomes saturated decreasing the
coupling, the brightness would have nowhere to go but down due the
residual inductance remaining in the two coils.

This is where you go off track - when the core saturates two things
happen - the inductance of the coils drops through the floor - less
inductance - higher current. The coupling also starts to fail as well -
so the bucking effect also decreases - bulb brighter...

This is where your logic goes wrong, in our perfect idealized
"transformer" with the secondaries connected in the "bucking"
configuration, and no DC in the primary, the inductance is already as
low as it can get, how can the inductance be less than zero when the
"transformer" is saturated?

News Flash, I am really liking the theory I advanced a few messages ago
that the "transformer" is not wound like an ordinary transformer, but
instead has one of the secondaries wound on each outside leg of the
E-core.

Not news - this would be common for a saturable reactor.

And not the case anyway as Dave has now posted a picture of his
"transformer" and all three windings appear to be wound on the center
leg.

The reason I am really liking this theory now is that I looked up the
service data for the General Electric E-155 which has the similar
Colorama tuning system, and the "transformer" is constructed exactly as
I speculated in my earlier message. If the S-W "transformer" is built
the same way then it is a whole new ball game.

Why? If in fact (as I've postulated most recently) that reactance is
indeed the greater control factor - then whether one coil of the two is
reversed or not would only effect the linearity of the control, not that
it works.

My belief all along is that the reactance is the control factor, that is
obvious, there is no other way for it to work. The question is how the
windings are actually connected, if they are connected series aiding
then I can understand how it works. If they are connected so they
"buck" then I don't see how a single leg configuration can work very
well, and the control law would seem to be reversed depending on the
connection, although maybe that's the point.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

John Byrns wrote:

This is where your logic goes wrong, in our perfect idealized
"transformer" with the secondaries connected in the "bucking"
configuration, and no DC in the primary, the inductance is already as
low as it can get, how can the inductance be less than zero when the
"transformer" is saturated?

Not talking transformer - but rather saturable reactor. Drawn similar -
but windings, core, etc. are different - and they don't interact the
same as a transformer. and I still think that's what's in the S/W. I
think if we get a side shot of the construction - we'll see three
leggs... maybe not.

Bucking - when talking about saturable reactors - bucking means one
winding reversed so that it's induced field is opposite the other
winding's field *when they meet at the control winding*. That would
translate to aiding as looking at the two load windings (but since
they're usually in a three legged config - the two don't interact as
such)... So yes - *one* of us has to "adjust" our perspective....

Again - look at the illustration at the bottom of this page::::

http://www.tpub.com/content/neets/14.../14180_138.htm

See the "buck" at the control winding - Note that this is "aid" at the
other load winding? Just the perspective it's viewed from, John.

best regards...
--
randy guttery

A Tender Tale - a page dedicated to those Ships and Crews
so vital to the United States Silent Service:
http://tendertale.com

In article wBnai.22483$dy1.20886@bigfe9,
Randy or Sherry Guttery wrote:

John Byrns wrote:

This is where your logic goes wrong, in our perfect idealized
"transformer" with the secondaries connected in the "bucking"
configuration, and no DC in the primary, the inductance is already as
low as it can get, how can the inductance be less than zero when the
"transformer" is saturated?

Not talking transformer - but rather saturable reactor. Drawn similar -
but windings, core, etc. are different - and they don't interact the
same as a transformer. and I still think that's what's in the S/W. I
think if we get a side shot of the construction - we'll see three
leggs... maybe not.

Bucking - when talking about saturable reactors - bucking means one
winding reversed so that it's induced field is opposite the other
winding's field *when they meet at the control winding*. That would
translate to aiding as looking at the two load windings (but since
they're usually in a three legged config - the two don't interact as
such)... So yes - *one* of us has to "adjust" our perspective....

That's not clear to me, I thought we were talking about all coils being
on the center leg, in which case what I said about "bucking" goes. I
thought I was the one that introduced the windings on three legs idea,
and I had the impression, perhaps wrongly, that you were resisting the
idea. At any rate in the three legged configuration I considered
"bucking" to work exactly as you are describing and simply didn't
realize you were talking about that configuration, so if I have it all
straight who's on first it appears neither of us have to adjust our
perspective.

And I am glad you caught the two outer leg windings on Dave's
transformer that I missed, with that input it all makes sense now.

Again - look at the illustration at the bottom of this page::::

Sorry I haven't had a chance to look at the links you posted yet.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

John Byrns wrote:

And I am glad you caught the two outer leg windings on Dave's
transformer that I missed, with that input it all makes sense now.

Note that in this kind of magnetic amplifier, the fluxes from the
reactance windings must cancel through the control winding. The reason
is that the control winding needs a lot of turns to make enough flux to
saturate the core with a small amount of current. On the other hand, the
reactance windings carry a lot of current, so they must have fewer
turns. Consider that this is a recipe for a transformer that puts high
voltage AC on the control winding unless the fluxes cancel there...

--
John Doty, Noqsi Aerospace, Ltd.
http://www.noqsi.com/
--
Specialization is for robots.

In article ,
John Doty wrote:

John Byrns wrote:

And I am glad you caught the two outer leg windings on Dave's
transformer that I missed, with that input it all makes sense now.

Note that in this kind of magnetic amplifier, the fluxes from the
reactance windings must cancel through the control winding. The reason
is that the control winding needs a lot of turns to make enough flux to
saturate the core with a small amount of current. On the other hand, the
reactance windings carry a lot of current, so they must have fewer
turns. Consider that this is a recipe for a transformer that puts high
voltage AC on the control winding unless the fluxes cancel there...

Yes, I understand that, in my first post on the subject I had proposed
that the S-W control reactor might have the two "secondary" windings
arranged on the two outer legs of the core so that it would operate as
you describe. Somehow I got the mistaken impression that Randy thought
all three windings were on the central leg of the core, which lead to me
thinking that all the windings were on the central leg when I first saw
the photograph, which doesn't clearly show the windings on the outer
legs because of the angle of the view. With the knowledge that the
secondaries are indeed wound on the outer legs, as I had originally
proposed, the mystery of its operation disappears, and Neil has even
provided a possible explanation for the usefulness of having the lamp
dim as the signal gets stronger.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/