From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Monday, September 15, 1997 8:03 PM
To: tesla-at-pupman-dot-com
Subject: Flybacks (was To Kevin)
Hi Alfred,
A comment on your comment on my comment :)
> From: Alfred A. Skrocki[SMTP:alfred.skrocki-at-cybernetworking-dot-com]
> Sent: Sunday, September 14, 1997 1:28 PM
> To: Tesla List
> Subject: Re: To Kevin
>
> On Sunday, September 14, 1997 5:14 PM Malcolm Watts
> [SMTP:MALCOLM-at-directorate.wnp.ac.nz] wrote;
>
> > My opinion for what it's worth:
<megasnip>
> > I think the flyback is fundamentally an induction coil. It works by
> > storing energy in the core, then releasing it from core to the load.
> > The TC we know and love on the other had is a cap discharge device
> > and is tuned to boot.
>
> I fundamentaly agree with Malcolm, a flyback transformer CAN NOT
> function without its ferrite core, by contrast a ferrite core would
> destroy a Tesla coils operation. I do differ with Malcom though on
> the issue of "tuned", typicaly flyback transformers are also tuned,
> in fact they are designed to resonate at about twice the horizontal
> oscillator's frequency roughly 30 KHz.
Flyback is a SMPS topology. It is not a requirement of a flyback
supply that any part of it be tuned. You are talking about one
designed for a particular application. The one I am building for
powering my coils is untuned but still a flyback nonetheless.
Moreover, a core is not a requirement for flyback operation. The only
thing that differentiates a flyback power supply from a forward one
is the use of a steering diode on the output side so that the switch
doesn't directly feel the load. In doing this, turns ratio doesn't
count in having a say in final output voltage. The only thing
governing output voltage in a flyback topology is the energy stored in
the coupled pri-sec inductors and the load on either or both coils if
coupling is tight. You can achieve pretty respectable coupling k > 0.9
in an air-cored transformer. You can do better by confining the flux
to an airgap with a core.
IMHO,
Malcolm