Shielded power-transformer

[Samuel Groner]

Hi

I'm looking for a shielded (i.e. mu-metal) power-transformer (toroid).
30 VA, 230-> 30 V. Any resources?

Thanks
Samuel

 

[John Larkin]

On 23 Jun 2004 22:12:20 -0700, micpreamp@yahoo.de (Samuel Groner)
wrote:

Hi

I'm looking for a shielded (i.e. mu-metal) power-transformer (toroid).
30 VA, 230-> 30 V. Any resources?

Thanks
Samuel

Properly-wound toroids leak very little magnetic field, and mu-metal
is very expensive. What's this for?

John

 

[Samuel Groner]

Properly-wound toroids leak very little magnetic field, and mu-metal
is very expensive. What's this for?

Audio mixer. I have 4 cm between the transformer and the summing
network - no way to change the layout. Would a 3 mm steel case around
the transformer help much?
Samuel

 

[John Larkin]

On 24 Jun 2004 22:17:22 -0700, micpreamp@yahoo.de (Samuel Groner)
wrote:

Properly-wound toroids leak very little magnetic field, and mu-metal
is very expensive. What's this for?

Audio mixer. I have 4 cm between the transformer and the summing
network - no way to change the layout. Would a 3 mm steel case around
the transformer help much?
Samuel

Probably not even 2:1. Thin sheet steel is fairly transparent to 60 Hz
mag fields. Use a torroidal transformer and keep any loops in the
mixer circuit down to minumum area, and keep the loops in the plane
that has minimum coupling to the transformer, if you can determine
that. Test the transformer to see if it leaks more at some point (like
at the wire terminations) and orient that away from the tender stuff.

You may need a grounded electrostatic shield - aluminum or copper will
work fine, aluminum foil tape even - to kill capacitive hum pickup at
these short distances.

If this is line level stuff, you shouldn't have much trouble from
magnetic coupling out of a torroid.

John