toroid transformer Q

[danial stocks]

>
>A thought suddenly struck me: I have mounted a 15 VA toroid transformer 
>inside
>an aluminum enclosure by means of a screw through the hole. But this screw 
>is
>in contact with the enclosure at both ends, actually. So isn't this then
>actually a winding, which is shorted??
>Is this bad? It has worked fine so far. The aluminum enclosure is just a 
>little
>bigger than the toroid itself. It doesn't get hot, nor does it make funny 
>noises.
>

This is a shorted turn, but toroids dont leak much flux.. [why they are so 
good for audio] so if the case is larger and fair distance from the trafo, 
shouldn't be a prob.. I had a very powerful transformer of conventional 
design in an aluminium case a few yrs back, odd things happened. When it was 
on the test bench [which had little bits of component legs snipped off all 
over the place] it would make a loud clack as it was switched on - the on 
surge generated a magnetic pulse which caused any little bits of wire under 
the case to jump up and hit it.. and with the aluminium lid on a very loud 
buzz emitted..shorted turn.. in the end I had to replace the aluminium lid 
with perspex. If you have a pro with a trafo, it will be obvious..
Cheers,
Dan
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