[Prev][Next][Index][Thread]

Re: [Fwd: Re: [Fwd: Re: [Fwd: Re: hyfrecator]]]


>From: Dan Gowin <gowin-at-epic-1.nwscc.sea06.navy.mil>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: [Fwd: Re: [Fwd: Re: [Fwd: Re: hyfrecator]]]
>

>> operate at the horizotal frequency. And, the push pull circuit
>> that we coilers use in our solid state Tesla coils is very similiar
>> to the horizotal circuit in a T.V.. So, the question is. Is solid
>> state Tesla coil "A Tesla coil" or are we simply driving a simple
>> induction coil? Or another question, by definition a Tesla coil
>> can only be an air resonate transformer?
>
>It's a tesla-coil as long as it's resonant.. On the other hand,
>flyback xformers in TVs etc. are not resonant and thus not 
>tesla-coils.
>
>> When I allow the field within an ignition coil to collapse the
>> output (o-scope) definately rings as if it were resonate. Or,
>
>It's rings because there is L and C in the circuit.. 
>
>>> >       The flyback transformer in a TV is a Tesla coil. The flyback
>>> > is designed to resonate at the horizontal scan frequency of 15 KHZ.
>>> > D. Gowin
>>> Not true. A flyback xformer is not resonant. It just dumps the
>>> energy into the core and thus gets HV to secondary because
>>> of inductance in secondary.. Simplified..
>>> Kristian.
>>Dan, I disagree with Kristian's statements. The photo in my book should
>>clear up any confusion. When I adjust the timing parameters, there is
>>a SPECIFIC frequency where the output signal really lights up! At this
>>point, the scope shows peak voltage waveforms, classic exponential
>>decay, and absolutely NO phase changes in the output waveform. If that
>>ain't resonance, I don't know what is...
>>- Brent
>
>Surely, there can and will be resonant frequencies with the flyback
>transformer but IN IT'S NORMAL USE it's not run resonant! 
>
>Heck, I'll have to actually measure the resonant frequency of several of
>the flybacks I have around here.. I'd bet that their resonant frequencies
>vary a great bit! Depending on core material, number of turns,
>size and shape of coil etc..
>
[snip]
Flyback switch mode power supplies (tv flybacks and others) are
designed to "charge" the core with a magnetic field, during which time
the secondary is BLOCKED with a diode (and NO power is transferred).
The primary is then open circuited, the magnetic field collapses and
the secondary (primary also) voltage reverses.  At this point, the
secondary's diode starts conducting and delivers power to the load.
It is NOT run in a resonant mode; if it were, it would be called a
resonant power supply! (how's that for a circular argument;)

Actually, resonant power supplies are designed so that the active
switche(s) (mosfet transistors these days) turn off during the "zero
voltage crossing" or "zero current crossing" portions of the primary
wave form.  This reduces energy loss in the switch.  These power
supplies are NOT tesla coils because the primary and secondaries are
not both in resonance.  This characteristic is the determining factor
between calling a circuit a resonant power supply and a Tesla Coil. Do
both the primary and secondary circuits resonate at the operating
frequency?  If they don't, it's not a Tesla Coil!

Now, if you were to add capacitance to both the primary and secondary
circuits of a flyback transformer (spark coils use the same idea) so
that they both resonated at the same frequency you'd have a tesla
coil. (And probably break down the insulation of that poor coil;)

	happy sparking,

	jim

(engineers, this has been a very simplified version;) send flames to
jim.fosse-at-bdt-dot-com)