Uh! Sorry Ray, it was near 2AM and I misread this. Of course
there's no gap in the core it's a linear AC transformer. No
DC in the windings and so no gap.

Usually I'd do everything I can to reduce any gap, inclduing
interleaving the laminations, to reduce the magnetizing current.

I just wasn't thinking, that happens sometimes.


raypsi wrote in news:ea79280c-6148-42a5-be23-
:

Shimmed the bobbin in the core window with some 1/8 thick
virgin teflon. Epoxied the windings to the bobbin. This was a 240VA
transformer and now is a 83watt buzzer / 157watt filament transformer.

Grumpy The Mule wrote:
Uh! Sorry Ray, it was near 2AM and I misread this. Of course
there's no gap in the core it's a linear AC transformer. No
DC in the windings and so no gap.

Usually I'd do everything I can to reduce any gap, inclduing
interleaving the laminations, to reduce the magnetizing current.

I just wasn't thinking, that happens sometimes.


raypsi wrote in news:ea79280c-6148-42a5-be23-
:

Shimmed the bobbin in the core window with some 1/8 thick
virgin teflon. Epoxied the windings to the bobbin. This was a 240VA
transformer and now is a 83watt buzzer / 157watt filament transformer.

Actually "transformers" that carry DC (IE: filter chokes) have a gap
formed by putting ALL the "E"s in one direction and ALL the "I"'s in the
other.

For transformers that carry SOME dc (audio output transformers) group
the "E"'s and "I"s in bundles and assemble with a few groups of bundles
going in opposing directions.

For transformers that carry ONLY dc (power, filament) alternate each
lamination so no two in a row go the same way.

ken scharf wrote:
Grumpy The Mule wrote:
Uh! Sorry Ray, it was near 2AM and I misread this. Of course
there's no gap in the core it's a linear AC transformer. No
DC in the windings and so no gap.

Usually I'd do everything I can to reduce any gap, inclduing
interleaving the laminations, to reduce the magnetizing current.

I just wasn't thinking, that happens sometimes.


raypsi wrote in news:ea79280c-6148-42a5-be23-
:

Shimmed the bobbin in the core window with some 1/8 thick
virgin teflon. Epoxied the windings to the bobbin. This was a 240VA
transformer and now is a 83watt buzzer / 157watt filament transformer.

Actually "transformers" that carry DC (IE: filter chokes) have a gap
formed by putting ALL the "E"s in one direction and ALL the "I"'s in the
other.

For transformers that carry SOME dc (audio output transformers) group
the "E"'s and "I"s in bundles and assemble with a few groups of bundles
going in opposing directions.

For transformers that carry ONLY dc (power, filament) alternate each
lamination so no two in a row go the same way.
I meant for transformers that carry ONLY AC! oops!

Yep, It's all about core saturation. A large utility
transformer can be saturated by just a few amperes
of DC. Which is one reason improvements in load current
THD are important. Zero sequence currents and all
that jazz.


ken scharf wrote in
:

ken scharf wrote:
For transformers that carry ONLY dc (power, filament) alternate each
lamination so no two in a row go the same way.
I meant for transformers that carry ONLY AC! oops!