Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!umd5!eneevax!noise
From: noise@eneevax.UUCP (Johnson Noise)
Newsgroups: sci.electronics
Subject: Re: toroid vs. stacked pole transformers
Message-ID: <1426@eneevax.UUCP>
Date: 1 May 88 21:12:44 GMT
References: <4496@husc6.harvard.edu> <2498@kitty.UUCP>
Reply-To: noise@eneevax.umd.edu.UUCP (Johnson Noise)
Organization: Elec. Eng. Dept., U of Maryland, College Park, MD 20742
Lines: 15
Keywords: toroid transformer


>In article <4496@husc6.harvard.edu>, kiely@lownlab.harvard.edu (James P. Kiely) writes:
> Given that toroid power transformers are lighter, more efficient,
> and generate a smaller spurious magnetic field than the more
> traditional stacked pole transformers, why doesn't everyone use toroids?
>

	One other point worth mentioning is that the efficiency gained
is simply not necessary (read not always with respect to manufacturing cost).
Conventional transformers can be very efficient (> 90%), suggesting that
other components may be the limiting factor in overall efficiency.  Consider
a dc-dc converter which uses some type of semiconductor switching element
(bipolar, thyristor, VMOS etc).  There is some voltage drop across the
element when the device is on, this turns into heat and wasted power.  This
can be very significant at low voltages.  Diodes also.