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Re: parallel secondary coils

Original poster: "Chris Swinson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <exxos-at-cps-games.co.uk>

HI Malcolm,

>            I am following your expts with interest. Please understand
> that I am not trying to be picky but would like to see a scientific
> reason if higher frequencies produce longer sparks. In my experience,
> the opposite has been true but that I do not attribute to frequency
> itself - more to the properties that low frequency coils have such as
> a generally higher primary surge impedance with correspondingly lower
> gap losses.

I can't really offer any scientific reasons for this, If there was good
reason then someone else on the list may have been able to say either way.
You say lower is better though it could well be better in general terms to
do this. Perhaps I should widthdraw my comments as I was just thinking that
higher frequency would give more power thoughput which would result in more
power to the arcs. I never considered greater gap losses or anything, it was
more of a assumption which I had. If everyone else has found lower frequency
better then fair enough, no harm done.  I havent as yet looked into this
fully so I could easily be proved wrong.

> > If 2 coils works better than one than why not ? a lot of things also as
> > rightly point out, though if it works better ( for what ever reason )
> > it could be a good thing to look into. There are far to many variables
> > my simple brain to work out with this idea which is why I posted the
> > experiments I did.
> The question is, why should they? The problem is, which particular
> variable or variables are behind the difference you are observing.
> You are altering more than just frequency.

I don't have the background as many Tesla coil builders do, I couldn't
really say that they should, or shouldn't, work better. I just found for me
that they did. Other factors can come into play which will of course alter
the running, my assumption is that the coils are interacting with each other
and giving each other  a bit more power. I am happy to be proved right or
wrong. If soemone else can find the same results as me and commet then we
have learn something, if no one else can get this setup to work then we
found out why not and we all learn something. Either way its worth

> >
> > I did have them connected at one point in parallel. If inductance is
> > then thats a alteration which will effect the tune point.  Will be
> > frequency which could be better for longer sparks.  I tried them about
> > 1.5foot appart and just a few inches appart. closer the better, but as I
> > stated arcs between coils become a problem. Connecting them in parallel
> > seem to work the best.  I wounder if there will be 2 frequencys at work
> > since both coils are not 110% in tune. Though I dont think this is
> > since it should act as a single coil since they are shorted together top
> > bottom.  Couldn't the EM off one coil compliment the other ?
> That brings up an interesting point. Since the two secondaries are
> coupled to one another, there will be transfers of energy between
> them, just as there would be between primary and secondary. Beating
> is almost certain to be present. That alone might account for the
> observed arcing between them.

I really didn't expect them to arc to each other. I expected the power to be
the same on the coils, so there shouldn't be any arcing as ech length of the
coil would have the same voltage. Though as they are close together then I
guess it would be easy for them to track from a high point on one coil and
hit a lower point on the other coil.  I don't thinkt he arcs were straight
and I think they did arc at a angle so that tells you something.  I dont
recall exactly how many inches it arced across, I will take better note on
this next time I do some tests with it.

> I realized last night that the self capacitance is not simply going
> to be an additive thing because of the proximity of the coils to one
> another. I suspect there will be shades of shading. In fact the whole
> setup would be a most interesting one to model. The number of
> variables present is interesting to say the least. Perhaps I might be
> tempted to drag some of my coils out of limbo and set them up in a
> similar fashion to take some measurements. I have been missing my
> ozone fix lately.

If someone can model this to get the self capacitance then it would be very
interesting to see what it came out as.

One thing which made me first thing of this dual coil idea is the fact that
even if you place 1 coil in the primary ( as normal ) and the second coil on
the outside of the primary, then you can draw good arcs from the second
coil.  Which made me think just to try 2 coils in the middle, couldn't
really hurt to try such a crazy idea could it ?!?!


> Regards,
> malcolm