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Re: 50%
Tesla List wrote:
>
> >> > Subject: 50%
> >> Subject: Re: 50%
> >> Subject: Re: 50%
>
> >From couturejh-at-worldnet.att-dot-netFri Nov 1 21:22:30 1996
> Date: Fri, 1 Nov 1996 05:36:13 +0000
> From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: 50%
>
> At 05:25 AM 10/31/96 +0000, you wrote:
> >> > Subject: 50%
> >> Subject: Re: 50%
> >
> >> >From bert.hickman-at-aquila-dot-comTue Oct 29 22:57:35 1996
> >> Date: Tue, 29 Oct 1996 20:44:19 -0800
> >> From: Bert Hickman <bert.hickman-at-aquila-dot-com>
> >> To: tesla-at-pupman-dot-com
> >> Subject: Re: 50%
> >>
> >> Richard and all,
> >>
> >> Well... I disagree. This is one of those areas where the commonly
> >> accepted theory may need to be more closely examined. I'm going to open
> >> myself up to MAJOR flamitude and claim that we_can_ break the 50% energy
> >> transfer limitation! The thought experiment below describes how this is
> >> theoretically possible. I also believe its possible in practice as well.
> >> I've verified this via PSPICE simulations, and it could be verified at
> >> low voltages using a MOSFET "gap". I've also done an estimate on my 10"
> >> coil in single-shot mode in a previous post to Robert Stephen which
> >> seems to indicate an ouput:input ratio of 56%.
> >>
> >> Safe coilin' to ya!
> >>
> >> -- Bert --
> -------------------------------------------------
>
> Bert -
>
> 1. The commonly accepted limit of 50% transfer (efficiencies?) is for the
> current and power and not for the energy transfer limitation. This is a
> common mistake made by many people.
>
Jack, I agree there is a difference. However, _if_ I can maximize the
energy transferred-per-bang, then I should be able to maximize the power
transferred by increasing the number of bangs/second. As long as I can
efficiently recharge my tank cap (helped perhaps by resonant charging
from the stored energy in the ballast or neon leakage inductance), I
should be able to get relatively high power efficiency as well. System
synergy at work...
> 2. Energy cannot be transferred instantaneously so the amount of transfer
> time is important and is determined by the coupling. The coupling must be
> correct for the 100% transfer of energy.
Yes... Fortunately, we have a fair amount of leeway, and quenching a
little too quickly appears to be somewhat better than quenching a little
too late.
>
> 3. The coupling does not take part in the energy transfer itself but is
> important in determining the transfer time. Maximizing K should be to
> coordinate the transfer time so 100% of the energy is transfered.
Well, the coupling is the mechanism by which the energy transfer occurs,
but this is only a semantic difference. Ideally, I'd maximize k until I
started seeing flashover problems, reduce k a little, retune the dwell
time to match, and tweak it again until I had it right...
>
> 4. Critical coupling may not give the correct time for 100% energy transfer.
Absolutely correct! The textbook definition of "critical coupling"
applies only to continuous sine-wave (CW) excitation. Capacitor
discharge coils run best at the highest coupling that can be safely
withstood by the insulation systems. This can be 10-100 times the CW
"critical coupling" value.
>
> 5. Quenching the gap at the appropiate time is important so all of the
> available energy is transfered. Proper quenching is also important for other
> reasons not related to energy transfer.
Agree - We've also got to blow out the arc from the power supply short
we've created before we can rapidly recharge the primary cap for the
next bang...
>
> 6. To obtain more output (spark length) with maggies compared to classical
> coils would not require more efficient energy transfer for the primary to
> secondary coils because it is already at 100%. However, it would require
> less total loss in the system which appears to be possible. I have never
> seen calculations of controlled tests that maggies do produce longer sparls
> compared to a properly designed and adjusted classical coil.
>
> Jack C.
Since it takes time to effect the energy transfer, and every microsecond
the gap fires continues to remove energy from the system, it becomes a
horserace. We need to transfer energy to the secondary as quickly as
possible to minimize gap losses, and higher k is the ONLY way (sort of
poetic, isn't it? :^)).
Here's where maggies _should_ outshine 2-coil systems, since a maggie
driver coil-pair can be set up for much higher k's than air-insulated
2-coil secondaries can withstand. Once we have a source of high current,
low impedance RF to drive the base of the teriary coil, series LC
resonant rise takes over, limited only be the Q of the coil. Richard's
Maggie 11E is, without a doubt, the reigning champion for longest arc
per coil length (>11:1), and MAY also be the champ for longest arclength
versus input power for its power class!
Has anyone gathered any sparklength vs power data for maggies?? Richard,
Greg???
Safe computin' to ya, Jack!
-- Bert --