Re: Stack of flat coils (was 8 kHz Tesla Coil)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Steve,

On 21 Sep 2005, at 18:06, Tesla list wrote:

> Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx>
>
> Peter,
>
> If you search the archives, you will find that years ago Richard Hull
> built a magnifier coil that was only 12 inch long, had a gigantic
> toroid on it (actually under it - he ran it inverted), and produced 10
> foot streamers/leaders.  So the ratio for his coil is 10:1.  But if
> you add in the height of the secondary coil that drove the extra coil,
> the ratio may be less than 4:1 and you might well beat his
> achievement.  So, for magnifiers, does the height of the secondary
> "count" or not? --Steve Y.

That depends on whether the design is such that at some instant, all
energy ends up in the resonator and therefore impresses the full
output voltage across it. I have my doubts that a 12" high coil can
sustain 500kV+ regardless of how brilliant the field control is.

Malcolm

> ----- Original Message -----
> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Tuesday, September 20, 2005 10:30 AM
> Subject: Re: Stack of flat coils (was 8 kHz Tesla Coil)
>
>
>  > Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>
>  >
>  > I have all the bits to make up a TC based on a stack of flat coils.
>  I > have the spacers, wire and acrylic base and oil tank to put it
>  in.  I > am aiming for 600 turns of heavy PVC coated wire in a one
>  foot high > coil.  I am aiming for a record coil to spark length
>  ratio with a > target of 4 foot sparks to give a 4:1 ratio.  The
>  winding of heavy > gauge wire in a single spiral will be a challenge.
>  >
>  http://tesladownunder.com/Tesla_coils_intro.htm#Multilayer%20Tesla%20
>  coil > > Peter > > > ----- Original Message ----- From: "Tesla list"
>  <tesla@xxxxxxxxxx> > To: <tesla@xxxxxxxxxx> > Sent: Tuesday,
>  September 20, 2005 2:52 AM > Subject: Re: 8 kHz Tesla Coil > > >
>  >Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx> > > >
>  >Hi Boris, > > > >Multilayer will have breakdown limitations which I
>  know you've > >already considered. Did you have some thoughts about
>  this as far as > >a specific winding technique? It will still have
>  the same RF loss > >issues, regardless. > > > >I think it was Antonio
>  who mentioned a stack of flat coils. This > >would be interesting to
>  look at. The distance between each flat coil > >would need to be
>  separated enough to prevent coil to coil breakdown. > >Winding
>  direction, id to od connection, all would be important to > >keep the
>  stacks as compressed as possible to take advantage of the >
>  >proximity (that would be the hard part). > > > >I wound one flat
>  coil a couple years ago. Pretty easy to do. I used > >a lazy Susan
>  turn table, layed down double sided carpet tape onto a > >sheet of
>  plexy, and started winding (round and round and round). The > >tape
>  helped keep the wire in place as the work went on. It would be >
>  >very interesting to wind several identical flat coils maybe only a >
>  >10" o.d. to keep the volts between stacks somewhat low. Flat coils >
>  >do have a tendency to arc along the surface when over stressed. > >
>  > >Using a 1x10 (id & od) with #24 is 400 turns at near 200 kHz 20" >
>  >above a ground plane. Putting an identical coil 1" above this coil >
>  >results in a drop in freq to about 130 kHz. The merit as I see it is
>  > >simply less wire, but there are breakdown obstacles to overcome
>  not > >only between stacks but also at the outer and inner edges. > >
>  > >I don't know, just contemplating the possibility. Maybe someone's
>  > >software out there could look this. But again, the RF losses are
>
>  > >independent of coil winding approaches, so no benefit in that >
>  >respect. And if nothing else, I guess it could be converted to an >
>  >induction coil with a little work. > > > >It's hard to beat
>  simplicity (single layer helical). > > > >Take care, > >Bart > > > >
>  > >
>
>
>