🚀 go-pugleaf

Tom Nagy, stud7b11@bcars564.bnrottawa asks:
>
>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?

Tom,

Here's some wisdom guzzled from that Texas mickey of wisdom,
the net. (yes I'm being sarcastic!)

Dave Dal Farra (gpz750@bnr.ca)
'83 GPz750/no fairing/no ABS/damn near no damping

-----------------------------------------attached----------->
Subject: Toroids
From: stephen.soyka@canrem.com (Stephen Soyka)
Date: Thu,  4 Nov 93 02:24:00 -0400

As a general rule, toroids are never a no-no. The usual overiding factor
in transformer topology is cost. Cost of the core, cost of the windings,
set-up time etc. In general, toroids are very expensive due to the high
labour costs involved. Every winding must be set up by hand becuase
winding machines use a rotating shuttle which must be pre-loaded with
the required length of conductor. I have a winding machine and can
attest to the pain-in-the-ass nature of this process.

That being said, a totoid is nothing more than a standard E-core wherein
the magnetic path is a perfect circle. This drastically reduces the
effects of eddy current losses and losses due to mutual inductance.

I'm not sure what you are getting at in the area of frequency response
and linearity. Aproperly designed XFMR is a properly designed XFMR.
Although it is somewhat difficult to control the physical linearity of
the actual winding, this is less of a problem with a toroid than with a
standard E-core.

-----------------------------------------------------------------------
---
From: dstock@hpqmoca.sqf.hp.com (David Stockton)
Subject: Re: Torroids for tube amp supply?
Date: Mon, 29 Nov 1993 16:37:44 GMT

 Toroidal transformers use tape-wound cores, explioting GOSS
(grain-oriented silicon steel) which has better mag properties in one
direstion than the other, The tape wound toroid ensures the mag field
always is optimally oriented. 

  Nearly all manufacturers have exploited this to the limit to run very
high flux levels, allowing them to reduce the number of turns per volt.
This can lead to a transformer that buzzes loudly, and also leads to
turn-on surges. Overrunning the voltage soon leads to saturation and
blown fuses (if you're lucky..)   44v windings may not have adequate or
legal insulation at line voltage.

  European transformer shops sell 240 to 110v isolating transformers for
operating power tools etc, running 110 into the 110 winding of one of
these, and bridge-rectifying the 240v winding to get over 300v DC may be
better  1) all windings running ar rated voltage, 2) isolting
transformers have special "safety class' insulation.

  For a good amplifier, I personally would have a custom transformer
done, with reduced flux level for acoustic noise reduction, and an
inter-winding electrostatic shield to prevent interference from line
transients.

-----------------end attachement---------------------------------