Can you stack torroidal transformers?

[tomchr]

Seriously, there should be no perceptible interaction between
two stacked toroidal transformers because magnetic flux in
the cores flows through the core, perpendicular to the wire
and very little flux even escapes the cores to cause any
interaction.

Actually, in his latest series of articles in EE Times, Douglas Self reports measurable differences between different toroidal transformer orientations. He states that you should rotate the transformer to find an orientation where the hum is minimized. So there is enough leakage field escaping. If you're using two transformers anyway, a simple and free way of minimizing the field would be to stack the transformers back-to-back.

~Tom

 

[imfree707]

Sounds Good To Me

Actually, in his latest series of articles in EE Times, Douglas Self reports measurable differences between different toroidal transformer orientations. He states that you should rotate the transformer to find an orientation where the hum is minimized. So there is enough leakage field escaping. If you're using two transformers anyway, a simple and free way of minimizing the field would be to stack the transformers back-to-back.

~Tom

Sounds good to me. It sounds analogous to RF shielding, where one
can reduce interference by several orders of magnitude, but never
quite completely eliminate it.

 

[tomchr]

Sounds good to me. It sounds analogous to RF shielding, where one
can reduce interference by several orders of magnitude, but never
quite completely eliminate it.

Yep. Nothing is perfect. It took me a little while to wrap my head around your analogy as field cancellation (using a field that's 180 degrees out of phase) and field attenuation (shielding) work by different mechanisms. But the analogy cuts to the chase and gets the point across.
It's the same situation as with the active noise cancelling headphones. Noise is sampled and played back 180 degrees out of phase, thus, resulting in silence.

Just one thing, though. Field cancellation attempted poorly will actually make matters worse.

~Tom