Re: Bert Pool's big coil
From: Bert Pool[SMTP:bertpool-at-flash-dot-net]
Sent: Monday, July 28, 1997 2:07 PM
To: Tesla List
Subject: Re: Bert Pool's big coil
> From: Greg Leyh[SMTP:lod-at-pacbell-dot-net]
> Sent: Sunday, July 27, 1997 5:10 PM
> To: Tesla List
> Subject: Re: New pictures
> Bert Pool wrote:
> > Stepping back from magnifiers for a short while, Bill Emery and I are
> > winding the largest conventional coil we've ever attempted. It is
> > 18.5 inches in diameter and 55.50 inches in length and is wound with
> > 14 gauge wire. The complete coil and form will weigh over 300
> > pounds. We will run this as a conventional coil, not a magnifier.
> > We expect minimum 15 foot sparks, and maybe some as long as 18 feet.
> My bet is that you'll get them; however you may need to raise the
> coil away from the ground significantly, or the ground strikes will
> limit the ultimate spark length.
Yeah, Bill agrees that we'll have to move it up - maybe we'll hang it
upside down like Richard Hull does his maggies! <grin>
> > The toroid will have a cross section of 20 inches and will be 8 feet
> > in diameter.
> Those toroid dimensions sound familiar...
> Are you using an 1800/2100 R49 earthmover innertube as the toroid form?
No, we have found a source of 20 inch diameter aluminum flex-duct. A
25 foot length is about $63 without tax.
> > We already have the coil form for a 28.5 inch diameter secondary. We
> > have 70 pounds of the 200+ pounds of 10 gauge enamel wire with which
> > we will wind it. We'll start with the 8 foot toroid and go from there.
> Thumbs up! You're not going to operate _that_ in your front yard, are you?
> BTW, what is the proposed winding length on the 28.5" secondary?
As a matter of fact, we probably will run it out in front. We've
taken a tape measure and if we set up where my driveway meets
the street, and supposing that we could produce 32 foot sparks (quite
a stretch, I admit), then we'd hit both the front of the garage and a
metal light pole across the street simultaneously. That would be
The length of the 28.5 inch coil will be three times its diameter, or
85.5 inches in length.