Transformer question

[Detector195]

Something I never quite caught when I took electrodynamics... What
determines the low frequency cutoff of a transformer?

Besides, I took electrodynamics as a physics student, and we never
learned about anything practical like transformers (unless they could
be solved in spherical coordinates of course).

 

[Tim Wescott]

Detector195 wrote:

Something I never quite caught when I took electrodynamics... What
determines the low frequency cutoff of a transformer?

Besides, I took electrodynamics as a physics student, and we never
learned about anything practical like transformers (unless they could
be solved in spherical coordinates of course).

I have a friend who's a physicist. When ever his wife asked him a
question about their new baby he'd say "wife, I can answer any baby
question you have -- as long as the baby in question is perfectly
spherical".

The low frequency cutoff in a non-resonant transformer happens when the
inductive reactance you see looking into the transformer is equal to the
resistive impedance of the source (or load). When one designs RF
wide-band transformers you generally try for an inductive reactance that
is 4x the load impedance, but you settle for less if you have to.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com