🚀 go-pugleaf

In article <36ue41$880@bcarh8ab.bnr.ca>, stud7b11@bcars564.bnrottawa wrote:

> Hi everyone.  Sorry about the crossposting, but I think
> this applies to all newgroups in question.
> 
> In an amplifier circuit that I am currently fiddling
> with, the spec. says to use a toroidal transformer in the
> power supply.  Why is this important?  How would I be
> degrading the performance of the amp with a plain-vanilla
> transformer?
> 
> Thanks in advance,
> 
> Tom Nagy
> 
> Please post responses, as I don't have email access.

There was a nice article about transformers in a German electronics
magazine (elrad) some years ago, I'll try to remember the basic points:

(all of the below concerns transformers with similar power ratings)

-toroidal transformers have less stray field than simple EI-core transformers
-toroidal transformers have a lower inner resistance (? I hope you know
what I mean) than simple EI transformers.

This leads to a faster charge-up of the capacitors, and to bigger problems
when turning them on (a 500 VA toroidal transformer will surely blow the
mains fuse, a similar EI-transformer probably won't)

- you can overcome these problems by using an EI transformer of a higher
power rating (more space, but probably still less money)
- or, for best performance, you can use other rectangular type
transformers (don't know the core types offhand), in conjunction with
oriented sheets (? you know, the flat metal parts that make up the core).
Price and weight, if produced in small series, is then roughly equivalent
to toroidal transformers, but performance is supposed to be better (and
they need more space).  

Sorry, can't find the exact refernce without the magazines - their
electronic database just isn't what it is supposed to be :-(

Bye
  Markus