[TCML] 4'-5' tesla coil sparks?

[Eric Goodchild]

On 2/10/2011 9:49 AM, jhowson4 at comcast.net wrote:
> Thanks for the advice Jim,
>
> Basically I am assisting on the design and getting the parts.
> The museum itself is doing all the actual installation and construction. Although i will probably end up helping out with winding the coils and the like. I presume that they know all about rigging and such, they are a reasonably large museum. The only question they could not readily answer was about the RF ground and the grounding of the Faraday cage to eliminate the interference. Is that even possible with a reasonable mesh size. I may take an RF meter and one of my small coils and do some tests just to see how much actually escapes from different types of cages.
> My question was, how would running an RF ground the long distance to the actual ground effect coil operation. or could the building structure or lighting grounds be used.
>
>
> Money is certainly an object, but if spending an extra hundred bucks gets a longer lasting capacitor then it would be in the better interest to go for the better capacitor. The goal is for under 800$.
> The museum is very, shall I say independent. They take a lot of pride in the "do it yourself" approach and have a warehouse devoted to the development of exhibits. I have brought up the fact that resonance research can do perfect installations of TC's a couple times.
>
>
>
> Thanks,
> John "Jay" Howson IV
>
>
> ----- Original Message -----
> From: "jimlux"<jimlux at earthlink.net>
> To: tesla at pupman.com
> Sent: Thursday, February 10, 2011 12:08:57 AM
> Subject: Re: [TCML] 4'-5' tesla coil sparks?
>
> On 2/9/11 9:16 AM, jhowson4 at comcast.net wrote:
>> Hello everyone,
>>
>> I am constructing a Tesla coil for The Rochester museum and Science Center.
>>
>> The goal is to have the coil mounted on the ceiling inside a Faraday cage with all the electronics mounted above the coils inside the ceiling.
>> Weight is supposedly not an issue.
>>
>> I was wondering if anyone had a time tested design that would produce a ~4'-5' arc. Hopefully with a power supply consisting of a couple 15/60's or something comparable. Durability is more of a concern than price.
>>
> Sounds like a fun project. You're looking at using a big MMC or a
> commercial cap from Maxwell, probably a rotary gap, and a small pole
> transformer or potential transformer. That 2-3 kVA range is on the
> ragged edge of being a good candidate for a static gap, I think. A
> static gap works fine as a "fire it up in the driveway and tinker with
> it" but it requires too much periodic fiddling for a permanent installation.
>
> If cost is no object, then, there are companies that actually do this
> for a business (Resonance Research, kVA Effects) and you could probably
> be involved in the process of selection, procurement, and installation.
>
>
> Now I'm going to rain on your parade a bit...
>
>
> Are you an employee of the museum? i.e. if something goes horribly
> wrong, who gets sued? If you're an employee, the museum does. If
> you're a volunteer, it's a bit more uncertain. If you're a vendor, then
> it's YOU. I can say, from personal experience, that getting liability
> insurance for a one-off tesla coil design/installation is prohibitively
> expensive.
>
> Upside down is no problem, but you'd want to check on mechanical
> supports. Do they have someone to do the mechanical design, or are you
> doing it? What about safety cables if something comes loose? Or, maybe,
> the Faraday cage will provide sufficient backup containment. Do you
> have someone to review and cross check your design and construction?
>
> What about electrical and building codes? They may have neglected to
> mention that aspect, but if you need to be "code-compliant" you need to
> figure out which codes, etc. Maybe you're technically "temporary
> theatrical equipment" or something like that? What sort of rigging
> experience do you (or someone who can work with you) have?
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$800 won't get you vary far from a reliability stand point. You could 
spend that just on the MMC if you used Maxwell pulse caps.