----- Original Message -----
From: "Joe Gwinn" <joegwinn@xxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Friday, October 17, 2003 6:50 PM
Subject: [OM] Re: [OT]Transformers (was Noisy T32 (wax potting))
> But for retrofitting a small power transformer, I wouldn't worry about a
new hole or two, even if it does raise the loss slightly. I suppose leaving
space so the bolt can have a insulating sleeve would help, as then any
connection would have to be via the burrs.
It's the burrs that do it.. To clean the hole you would need to use an
expanding reamer rather than a drill.
> I would be far more worried about accidentally damaging the transformer
while drilling, unless I could remove the core from the winding. If the
core is removable, then it ought to be possible to deburr the holes. But
this is a lot of work.
And you'd never get it back together again! The potting varnish is designed
to penetrate between the laminations and secure them. If you separate them,
the will be a comlete mes and won't all go back in. If you clean them up,
you'll end up with aa dry lamiated transformer which will re - define
buzzing for you.
>
> Anyway, this is why I preferred wax potting. No disassemby needed, and
wax won't hurt anything.
Agreed as long as it's not so thick as to overheat the centre of the coil.
> Maybe it matters for an audio output amp, which has to handle a wideband
(20 to 20000 Hz) signal without distortion, but for a one-frequency power
transformer it likely matters far less, so long as the power loss isn't
excessive.
Depends on the definition of excessive. Eddy currents equal heat production,
so things can get tricky. You wouldn't want your wall - wart to melt while
plugged in, would you? Very few people allow these things sufficient
ventilation, so they can be quite marginal on temperature. Adding heat is
not good in these circumstances. If they weren't so ugly people might not
hide them behind the furniture...:-)
>
> Valve amps are making a comeback in hi-fi circles (for the mellow tube
sound) and never died for guitar amps (for a better grade of distortion), so
a new career awaits you.
I was privileged to work for probably the greatest valve amp designer
living. I am now privileged to count him among my friends (even though he
likes N*k*ns). By comparison my "talents" in this area are pitiful, added to
which, so much of a subsequent life has needed to be absorbed that I can't
remember most of the old skills.
Not all valve amps are "mellow", but good ones are "clean", certainly more
so than the best of transistor. Our were serious butt - kickers. His currnt
ones still are.
>
> Joe Gwinn
Julian
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