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Re: Flybacks (was To Kevin)


From: 	Robert Michaels[SMTP:robert.michaels-at-online.sme-dot-org]
Sent: 	Tuesday, September 16, 1997 2:38 PM
To: 	tesla-at-pupman-dot-com
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

                                        Robert Michaels



TL>From:  Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
TL>Sent:  Monday, September 15, 1997 8:03 PM

TL>Hi Alfred,
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>>
TL>> On Sunday, September 14, 1997 5:14 PM Malcolm Watts
TL>> [SMTP:MALCOLM-at-directorate.wnp.ac.nz] wrote;
TL>>
TL>> > My opinion for what it's worth:
TL><megasnip>

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>>
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.

TL>IMHO,
TL>Malcolm