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Re: [TCML] Variable Ballast



Hi all,

The toroid is 14.5 inches on the ring diameter and the main diameter is 56" dia. The secondary......with the toroid.....and with a 10' leader off the toroid all resonate at 53 khz. Tested for this last night! The toroid was built using foam panels 3.5" thick. Very similar construction as spelled out in HVTESLA.COM . I put 1/4" ply on the top and bottom sides of the inner toroid. Filled the gaps with foam and spun on an axle of 2" PVC right thru the center. This allowed me to spin the whole unit between two picnic tables with my 1/2" drill using a variac . I smoothed the foam ring now rough as all get out with a 90 deg. grinder with a very aggressive sanding disk. The foam was all over me! Not a project for indoors as the foam is now all over the yard and blowing everywhere. Wife is not happy......go figure! The a layer of spackling was applied and later sanded to just smooth the rough foam out. Then primed with stain blocking primer. Then a layer of fiber glass was applied all over.....this was to add surface strength as the foam is very soft and dents easily. Then another layer of spackling and then sanded smooth. This is where doing body work came in handy! Then primed again and then a layer of aluminum tape was added for the final finish. This thing looks like it was turned on a lathe!......well it was sort of! The 1/4" ply gives me the base I needed to support the toroid and to mount the upper terminal to.

The cool thing is the toroid is not real heavy.  50-60 lbs.

The entire unit was assembled yesterday and stands around 10' tall. Yes I have plenty of room to get it in and out of the barn.

Does anyone know the address for the Teslathon at Roger's in Chillicothe this coming weekend? Got the invite from Roger but not the address. Is anyone else going?

Bud Mohrman

-----Original Message----- From: Phil
Sent: Saturday, August 01, 2015 4:16 AM
To: 'Tesla Coil Mailing List'
Subject: Re: [TCML] Variable Ballast

Bud,
This sounds like a very interesting coil being created! What size minor dia'
toroid are you using and is it SRSG or ARSG, 120/240 bps?
Don't forget to post a YouTube link


Regards
Phil Tuck

www.hvtesla.com



-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Buds tape mail
Sent: 31 July 2015 13:22
To: Tesla Coil Mailing List
Subject: Re: [TCML] Variable Ballast

Hi Phil and others,  I have been reading thru your web site and Richie's
very thoroughly.  I have built  a 12" X 51" secondary #18 wire and have
finished a 56" toroid and will have this thing ready to go very soon.  I
have a rotary spark gap (copy of Ed's in Rochester) and a 14kv pole pig.  I
have been reading extensively about primary inductive ballast.  I do have
two 225 amp buzz boxes I could use in parallel as ballast like others have
done.  I understand the principle series on the primary side limiting the
power to the pig.

I saw how and why you wound your own ballast.  My question is
this........can we just use a very large welding transformer........say 400
amp unit as the ballast while shorting the secondary or should we just bite
the bullet and wind a huge ballast from an older transformer with a huge
iron core?  I have my own machine shop.......... www.tape-inc.com
..........and can do almost anything once I know what it is I need to do.  I

think most of us do not know the how and whys of ballast design.....you know

the core size min/max and wire size min/max for a pig of this size.

Bud Mohrman

-----Original Message----- From: Phil
Sent: Friday, July 31, 2015 5:16 AM
To: 'Yurtle Turtle' ; 'Tesla Coil Mailing List'
Subject: Re: [TCML] Variable Ballast

Jon,
The modern cheap import ones you see knocking about are generally not up to
the job for a pole pig, without getting pretty hot during use. I melted and
shorted the windings of one a while back while running @ 10.5kv / 400mA -
(hardly pig output) simply because I left it running for several minutes
(they normally have a thermal cutout to disconnect the mains input during
normal use)
Their duty cycle is very low sometimes, especially as Yurtle mentions, if
Alu' conductor is used; also the resulting voltage drop from lossy windings
gets multiplied up by the pig, so you could potentially be losing 0.5kv at
the worst case.
Winding your own ballast is a better option.


Regards
Phil Tuck

www.hvtesla.com



-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Yurtle Turtle via

Tesla
Sent: 30 July 2015 20:52
To: GENE GARRAGE; Tesla Coil Mailing List; Tesla Coil Mailing List
Subject: Re: [TCML] Variable Ballast

I got a 225 amp Lincoln welder at a garage sale.It was old enough to have
copper windings. I chose to short the welding leads internally, and
eliminate the cables.

     From: GENE GARRAGE via Tesla <tesla@xxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Wednesday, July 29, 2015 6:53 PM
Subject: Re: [TCML] Variable Ballast


     From: Jon Danniken <danniken@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Thursday, July 2, 2015 2:28 PM
Subject: Re: [TCML] Variable Ballast

On 07/01/2015 11:14 AM, Miles Mauldin wrote:
Do I need to find an old welder, or will an inexpensive new one work
just as well. Read many posts about shorting the secondary and using
the primary in line with a pole pig. Thoughts, ideas or suggestions
all wanted for a variable ballast.

You can get an old 220V arc welder for cheap on craigslist if you are
patient,  less cheap if you are not patient.  As a bonus, you also get a
welder.

Jon
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