Re: Flybacks (was To Kevin)
From: Robert Michaels[SMTP:robert.michaels-at-online.sme-dot-org]
Sent: Tuesday, September 16, 1997 2:38 PM
Subject: Flybacks (was To Kevin)
The erudition and logic in your post is hard to refute,
Malcolm on any technical basis.
Howsoforeverbethatasitmay -- I respectfully submit that
flyback transformers resemble Tesla coils in that flybacks
generate (and in the practical realization =depend upon=)
high-voltage at high-frequency.
It is this combination: high-voltage and high-frequency,
together, that characterizes much of the work and related
discoveries of Dr. Tesla.
Ergo -- In my book a flyback transformer is a modern applica-
tion of Dr. Tesla's work. That it also resembles a switching
power supply does not detract from this. That it does not
depend upon a tuned primary/secondary serves to differentiate
it from a Tesla coil per se -- yes that is so. But hey --
there is precious, precious little everyday use of Tesla
currents. Don't try to take flybacks away from us!
Fighting for Dr. Tesla, in
-- Detroit, USA
TL>From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
TL>Sent: Monday, September 15, 1997 8:03 PM
TL> A comment on your comment on my comment :)
TL>> From: Alfred A. Skrocki[SMTP:alfred.skrocki-at-cybernetworking-dot-com]
TL>> Sent: Sunday, September 14, 1997 1:28 PM
TL>> To: Tesla List
TL>> Subject: Re: To Kevin
TL>> On Sunday, September 14, 1997 5:14 PM Malcolm Watts
TL>> [SMTP:MALCOLM-at-directorate.wnp.ac.nz] wrote;
TL>> > My opinion for what it's worth:
TL>> > I think the flyback is fundamentally an induction coil. It works by
TL>> > storing energy in the core, then releasing it from core to the load.
TL>> > The TC we know and love on the other had is a cap discharge device
TL>> > and is tuned to boot.
TL>> I fundamentaly agree with Malcolm, a flyback transformer CAN NOT
TL>> function without its ferrite core, by contrast a ferrite core would
TL>> destroy a Tesla coils operation. I do differ with Malcom though on
TL>> the issue of "tuned", typicaly flyback transformers are also tuned,
TL>> in fact they are designed to resonate at about twice the horizontal
TL>> oscillator's frequency roughly 30 KHz.
TL>Flyback is a SMPS topology. It is not a requirement of a flyback
TL>supply that any part of it be tuned. You are talking about one
TL>designed for a particular application. The one I am building for
TL>powering my coils is untuned but still a flyback nonetheless.
TL>Moreover, a core is not a requirement for flyback operation. The only
TL>thing that differentiates a flyback power supply from a forward one
TL>is the use of a steering diode on the output side so that the switch
TL>doesn't directly feel the load. In doing this, turns ratio doesn't
TL>count in having a say in final output voltage. The only thing
TL>governing output voltage in a flyback topology is the energy stored in
TL>the coupled pri-sec inductors and the load on either or both coils if
TL>coupling is tight. You can achieve pretty respectable coupling k > 0.9
TL>in an air-cored transformer. You can do better by confining the flux
TL>to an airgap with a core.