RE: Effective Resistance

["Malcolm Watts" <M.J.Watts-at-massey.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi John,

On 28 Aug 00, at 20:28, Tesla list wrote:

> Original poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net> 
> 
> 
> Malcolm -
> 
> You pointed out the problem by using your example. There is more than one
> type of Q factor with Tesla coils. If you use the wrong Q factor you get 2.7
> MV of voltage. You must use the operating Q factor to get the correct
> voltage. You will find this Q by using the correct Reff resistance. The
> problem is to find the correct Reff resistance (ESR?). How do you do that?
> Refer to my post "Q Factor and Overall Efficiency". What are your comments?

My comments are: unloaded Q does not substantially change 
between driving my coil with low or high energy. I've sent 
another post to the list on this. 
      Let me explain why you equation doesn't work: You are 
putting a limited shot of energy into the coil per bang and 
the capacitances it has to charge can only allow the voltage 
to go so high. Even were the Q to be infinite, you could not 
do better. Q being less than infinite simply indicates that 
even this ideal will not be reached. I've explained time and 
time again how to calculate ESR using two different methods. 
It is in the archives. I will not bore the list further.

Regards,
Malcolm
 
 
> Coilers have been banging this Q factor problem around for years. It usually
> ends up with no agreement amongst the coilers. However, if you are to
> include the Q factor and effective resistance in a program like the JHCTES I
> believe doing something with the data you have available is better than
> doing nothing. More data is needed. But it's the same old problem. There are
> not enough coilers like you who go beyond the spark stage and do more
> testing of their coils.
> 
> John Couture
> 
> --------------------------------
> 
> 
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Sunday, August 27, 2000 11:21 PM
> To: tesla-at-pupman-dot-com
> Subject: RE: Effective Resistance
> 
> 
> Original poster: "Malcolm Watts" <M.J.Watts-at-massey.ac.nz>
> 
> Hi John,
>           I don't think there is too much of a problem here:
> 
> --------------------------  snip
> 
> 
> I presume that means that my coil which has an unloaded Q of
> 300 odd and a primary voltage of 9kV is generating 2.7MV!!!???
> I can assure you it isn't. More like 300kV actually. That
> equation only applies to a CW-driven coil with no breakout.
> 
> -------------------------- snip
> 
>   But
> > first of all the Reff must be cleary defined. For example is Reff the ESR
> > that coilers talk about? The ESR is referred to as an impedance but the
> Reff
> > can not be an impedance. The Reff is a loss type ohms. An impedance is the
> > sq rt of the squares of the active and reactive ohms. Note that there are
> > three types of ohms in the electrical world, active, reactive, and
> > impedance.
> 
> ESR = Equivalent Series *RESISTANCE*. Disipative resistance -
> no complex impedances in there.
> 
> Regards,
> Malcolm
> 
> > As you can see there is much more to the design and engineering of the
> Tesla
> > coil once you get beyond the spark stage.
> >
> > John Couture
> 
> 
>