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Who or what is Q [Length to Dia ratio]




----------
From:  James [SMTP:elgersmad-at-email.msn-dot-com]
Sent:  Monday, August 24, 1998 1:37 AM
To:  Tesla List
Subject:  Re: Who or what is Q  [Length to Dia ratio]


>From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
>Sent:  Sunday, August 23, 1998 9:48 AM
>To:  Tesla List
>Subject:  Re: Who or what is Q
>
>to: Reinhard
>
>While it is true that pi seems to be the optimum value for efficient energy
>transfer and potential production, this value falls short of good design
>criteria when the flashover potential of the secondary is considered.  With
>modern design parameters producing arc discharges of 2-3X the sec coil
>length, this pi value ratio, if used, will only produce headaches and
>burned sec coils.  We have long ago standardized our commercial units to a
>value of 4.5:1 and 5:1 which seems to be the optimum blend for both
>potential generation and flashover protection.  Consider 4.5:1 for all
>small to medium coils and 5:1 for units running over 10 kva and you will
>produce powerful discharges with minimum flashover problems.  We have used
>these design parameters in units producing spark lengths up to 76 ft
>without additional problems.  Our "Big Bruiser" which was displayed at our
>fall open house last year uses a 5:1 ratio.
>
>DR.RESONANCE-at-next-wave-dot-net
>
>
>----------
>From: Tesla List <tesla-at-pupman-dot-com>
>To: 'Tesla List' <tesla-at-pupman-dot-com>
>Subject: Who or what is Q
>Date: Saturday, August 22, 1998 9:55 PM
>
>
>----------
>From:  W Y Liu [SMTP:eenwyl-at-sun.leeds.ac.uk]
>Sent:  Saturday, August 22, 1998 10:06 PM
>To:  tesla-at-pupman-dot-com
>Subject:  Re: Who or what is Q
>
>
>Given that there is an oscillator of Q=100, the time constant
>of the turn-on transient for this oscillator is roughly 100
>cycles of the oscillation frequency in length.
>
>
>Louis
>(non-coiler)
>
>> From tesla-request-at-pupman-dot-com Sat Aug 22 22:40 BST 1998
>> Resent-Date: Sat, 22 Aug 1998 15:35:48 -0600
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>> Subject: Who or what is Q
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>>
>>
>> ----------
>> From:  RWB355-at-aol-dot-com [SMTP:RWB355-at-aol-dot-com]
>> Sent:  Saturday, August 22, 1998 12:41 PM
>> To:  fwd
>> Subject:  Who or what is Q
>>
>> Hi all,
>>
>> There has been a lot of talk about "Q". Let me see if I can shed some
>light on
>>  who or what Q is.
>> NO Q isnīt that dude from Star Trek.
>> Q is a ratio factor that describes the behavior of a circuit. Without
>running
>>  a lot of math:
>>
>>        w(omega) * L
>> Q=   ------------------ Lets simplify this as w=2* pi*F
>>             R.
>>           2*pi*f*L
>> =     ------------------
>>              R
>>
>> So this means Q is the ratio of inductive reactance to (ohmical)
>resistance.
>>  The higer your Q is (Read: high inductive part, low resistance part) the
>>  "sharper" your resonance curve is (if you plot it). A small Q (e.g.=1)
>would
>>  give you a lazy curve like an upside down "U". A high Q (e.g. 1000) on
>the
>>  other hand would give you a fast rise / fast drop curve with a real
>needle
>>  point as the peak value. The "cut-off", if you will, is much harder.
>Taking
>>  this and the transformer laws into account you can now  see why a high Q
>coil
>>  will be able to produce a longer and fatter spark. This also shows why
>you
>>  canīt (like I first did, growl!!) just go to wire length calculations
>for
>your
>>  secondary. A small coil (high h/d ratio) will have a different
>inductance
>than
>>  a big coil (low h/d ratio) wound with the same length of wire. The big
>coil
>>  (using thicker wire) has a better Q, so it will perform better. Of
>course you
>>  need to adjust the input power for the bigger coil. The bigger coil will
>need
>>  more juice. But if you connect your big ps to the smaller coil you will
>get
>>  less output bang for your money. What I find very intersting is that the
>>  optimal h/d ratio turns out to be Pi (3.14159 etc), but it does make
>sense if
>>  you look at several ac equations.
>>
>> coiler greetings,
>> Reinhard
>>
>>
>>
>----------
>
    Ha, Ha, there are 3 forms of Q, One that was mention, another that has
nothing to do with a tuned circuit, but transistor biasing, and the most
important to achieve a higher than input output in watts is the flywheel
effects definition of Q..  A resonant circuit will ring as it were, for a
period of time after a voltage spike has been applied that matches the
circuits initial impedance, it has to do with how many cycles follow the
discharge, and mostly the ratio of energy lost on a 1 to what the circuit
does.  If you have a Q factor of 4,000, then if you could drive the circuit
matching it's impedance at the resonant frequency, on a no load, or
resistive load condition of the secondary, then 1/4000th the energy is
demanded from the driver circuit..  On start up at that frequency the value
of Xc,and Xl would only be equal at 100 ohms, but the DC resistance is less
than .05 ohms.  Then for the circuit to start up, and run you have to match
the initial 50 ohm AC load, just to get it to kick on at the resonant
frequecy, and drop the output demand of the driver circuit, and place the
full amount of energy in watts on the output.

    I tried to explain about resistive loads, and the effects on the
primary, when all it does is drive down the resonant frequecy compared to an
open load on the secondary.  Most of the facts revolve around how the
primary only sees the load on the secondary as a change in it's inductance.
So, the primary's inductance is high on a open load, and low on a short.
This means arcs are bad, but lighting can be cheap.  You could almost run a
100 watt light bulb off of a 6 volt lantern battery for as long as you could
one of the bulbs that it normally uses.  It's just a matter of resonance.