Re: Surprised by power supply design

From: John Popelish (jpopelish_at_rica.net)
Date: 12/29/04 

Date: Wed, 29 Dec 2004 12:55:57 -0500

martin griffith wrote:
>
> On Wed, 29 Dec 2004 00:08:42 GMT, in sci.electronics.design Rich Grise
> <richgrise@example.net> wrote:
>
> >On Tue, 28 Dec 2004 15:19:08 -0500, BFoelsch wrote:
> >
> >> I ordered a 13.8 volt, 4 amp power supply (battery eliminator) from one of
> >> the "tier 2" manufacturers of such stuff. (BK Precision)
> >>
> >> Anyway, I received this thing, it works fine and meets all specs, but I was
> >> shocked to find out that this is a linear power supply! Stranger yet, it is
> >> completely discrete, not an IC in it.
> >>
> >> I had kind of suspected that at the $40 price point I would get something a
> >> bit less, uh, heavy. but it has a genuine 50/60 Hz transformer in it.
> >>
> >> Isn't this a bit odd in 2004? I expected a switcher, or perhaps a linear
> >> with a 1 package regulation solution.
> >>
> >> Any opinions?
> >
> >My opinion is that you're very lucky! Did you happen to notice if the
> >tranny is ferroresonant? That makes the regulator a lot cheaper, like you
> >don't need one at all. ;-) The circuitry is probably just timers and
> >protection, if it is a ferro.
> >
> >Cheers!
> >Rich
> >
> how do you spot a ferroresonant tranny?

Look for the magnetic shunts and oil filled resonating capacitor
(see diagram 1).
http://www.marelco.com/an/an17.htm 

-- 
John Popelish

Relevant Pages

  • Re: Just bought old Fender Bassman
    ... >The small tranny is the output tranny, the big one is the power ... so if it's rusty it might be bad, but you might be lucky. ... The large black one is the power tranny, ...
    (alt.guitar.amps)
  • Re: Just bought old Fender Bassman
    ... The small tranny is the output tranny, the big one is the power ... so if it's rusty it might be bad, but you might be lucky. ...
    (alt.guitar.amps)