Re: Ferrite Cores - Where's the Gap? (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 08 Apr 2004 08:08:27 +0930
From: Matthew Smith <matt@xxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Ferrite Cores - Where's the Gap? (fwd)

Malcolm

>       HV and EHT supplies are not always flyback supplies. For
> instance, many of the so-called flyback supplies built by people in
> this circle are actually self-oscillating forward (often pushpull)
> converters. Sorry if this sounds like pure pedantry but this is an
> engineering forum of sorts and it is helpful to get accurate
> descriptions of equipment to facilitate long-distance troubleshooting.

This is certainly helping me!  I've been trying to learn my SMPS stuff from a
Linear Technology application note.  It's pretty comprehensive and more easy to
get to grips with than most text books (which you can't get round here anyway),
but doesn't cover everything.

My original question related to the type of transformer used for TV line-out.  I
have just taken one apart and confirm the absence of any type of spacer.  Does
this mean that it is wrong to assume that the line-out from a TV is actually a
flyback transformer?

Can you confirm, therefore, what topology you consider to be a single-ended
(switched DC) supply to be - which looks to all intents and purposes like
flyback topology - but without the core gap?  In other words, take the gap out
of a "flyback" transformer, and what do we get?

If popular usage of a term is causing confusion, maybe it is best that we get
our terminology right and start to call things what they really are!  (Either
that, or give up and go into politics.)

Does anyone know if there's a "SMPS design for Dummies" ;-?  I think I could do
with it...

Lastly, to save wearing out my calculator/brain, I'm going to be putting all the
main formulae from the application note into a spreadsheet - I'll post it to my
site if it would be of any interest to anyone.

Cheers

M

-- 
Matthew Smith
Kadina Business Consultancy
South Australia
http://www.kbc.net.au