[sdiy] Fixing humming transformers in 1u rack units

[Graham Atkins]

Toroidal manufacturers usually give specific instructions relating to  
this
as incorrect mounting can lead to serious or permanent damage to the
transformer. The metal base of a unit and mounting bolt form part of a
circuit passing through the toroid. If mechanically attached to say the
lid, this completes the magnetic circuit.

Graham

On 20 Feb 2010, at 19:00, Magnus Danielson wrote:

> cheater cheater wrote:
>>> Toroidal transformers are a different matter.  Due to the shape of  
>>> the
>>> core, they have much lower divergent flux.  BUT if you happen to,  
>>> say,
>>> mount it with a bolt that runs through the center hole and  
>>> connects to
>>> the chassis on both sides, this effectively adds another winding  
>>> to the
>>> transformer.  You really don't want that to happen.
>> Why?
>> Will that work as a secondary winding in an ac/dc transformer?
>
> It will act as another secondary winding in a ac transformer (there  
> is no such thing as an ac/dc transformer).
>
> This secondary winding will load the transformer. Breaking the  
> conduction path by using isolating washers would help.
>
> Cheers,
> Magnus
>
> Cheers,
> Magnus
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