John Byrns wrote:
In article ,
Randy or Sherry Guttery wrote:

John Byrns wrote:

Is one or the other really necessarily a "bonus", don't they work in
opposite directions assuming the two windings are connected in a
"bucking" configuration?
No - because "bucking" would be dependent on good coupling... Which
happens when the core is NOT saturated - so saturated - not bucking -
bright.

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. 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.

So coupling drops when saturated - so saturated - low coupling - dim

This works against the reactance effect you describe below.

Reactance drops when saturated - so saturated - low reactance - bright.

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.

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.

Of course we don't actually know they are
really connected in a "bucking" configuration, we are just speculating
they are because of the way the schematic is drawn.
I'd be VERY surprised if they are not... 1) why have two windings if
"bucking" (or as I speculated previously -- phase reversal to provide
symmetry) was not needed? 2) why take the extra effort to draw the
schematic that way?

See above.

I'm glad you are the one working all this out, I would like to see more
information on the construction of the transformer and the disposition
of the windings before speculating too much. If the transformer is of
open frame construction and is not potted, the OP should be able to
easily determine if an E-core is used and if all the windings are on the
center leg?
Since I don't have "hands on" access - I am left with few options: 1)
guess. 2) offer to see if I can fix the thing. (did I really say that???).

The thing that bothers me about that is if the laminations (assuming
(that dangerous word!) traditional construction) are welded... it might
be extremely tough to get it apart to get at the bobbins... Yes
pictures worth 1K words...

I have seen several posts in rec.antiques.radio+phono over the years
from people who have rewound the GE "transformers", although I don't
remember who they were from.


Regards,

John Byrns

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.

NO. If the coupling were perfect, the light would be dim because the two
windings are bucking their max., preventing current flow to the lamp. Ken