Re: Maggies and such

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

On 15 Aug 00, at 10:58, Tesla list wrote:

> Original poster: "sundog" <sundog-at-timeship-dot-net> 
> 
> 
>  Hi all!
> 
>   A question on magnifiers....
> 
>     I am guessing that the secondary and tertiary coils have to be at the
> same resonant freq.  Makes sense to me that they would be.  But will having
> different inductances (a big fat driver with mediocre turns and a tertiary
> that's wound with finer wire for more turns so they have the same res.
> freq)..ideas?  I'm wanting to get the surge impedance down on the driver so
> it can be coupled tighter.  Yep, gap losses go up, but this is for
> examination more than long sparks.

The coils do not have to run at the same frequency. For a 
conventional slap-it-together system (i.e. without Dr de 
Queiroz's special k's incorporated) you treat the 
secondary+tertiary as a single entity and tune the primary to 
the combination. The voltage rise across each will be in 
proportion to each coil's contribution to the total 
inductance. You can couple the primary as closely to the 
secondary as you like but overall coupling is determined by 
the proportion of total inductance coupled to the primary 
(i.e. going for k=0.6 in the driver is not going to score you 
an overall coupling of 0.6 - far from it in fact).  Your 
sparklength is pretty much dependent on how much power makes 
it to the secondary+extra coil and the peak voltage the system 
reaches, so going for low losses in the primary is still a 
good idea.

Regards,
Malcolm