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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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