Re: [TCML] Transformer

[robert@xxxxxxxxxx]

Thank you all for the advice. I did pick up that transformer for one reason I was in the town where it was located working today, so I saved on the shipping. I was also able to pick up a 15/60 NST also at a sigh shop for free. The only problem is, it is a gfi type. Can the gfi be removed? And can we work with that big xray tranny and make it work also. I don't mind a good complex challenge. If you all can stand holding my hand through it I' game to give it a go.

Thanks again for all the help so far.

Rob
KI4HXT
Sent via BlackBerry by AT&T

-----Original Message-----
From: Quarkster <quarkster@xxxxxxx>

Date: Tue, 5 Aug 2008 10:56:13 
To: Tesla Coil Mailing List<tesla@xxxxxxxxxx>
Subject: Re: [TCML] Transformer


Robert -
   
  You didn't provide any information on your intend use, so it is difficult to make any sort of recommendations without more data.
   
  If you intend to make a Tesla coil, an X-ray transformer is inappropriate, especially for a first coil. The output voltage of a 50KV transformer is too high for Tesla coil use without the use of exotic construction techniques, and finding or making a tank capacitor that will operate at 50KV will be difficult and/or costly.
   
  Conventional spark-gap Tesla coils typically utilize transformer output voltages in the range of 7.5KV to 15KV. This allows the transformer and tank circuit to operate with air insulation, rather than requiring everything to be submerged in insulating oil. Tank capacitors can be easily assembled from arrays of smaller, lower voltage capacitors (MMC), ending up with an effective voltage rating of 20-25KV.
   
  Your best bet is to find an older (non-GFI) neon sign transformer, 10.5 to 15KV output at 30 or 60ma. These can frequently be obtained at low cost from neon sign shops, or on eBay. Multiple transformers of the same voltage rating can be connected in  parallel for higher current output.
   
  The seller of the transformer in your link did not mention that X-ray transformers are rated for an extremely low duty cycle (typically <5%) to prevent overheating. If you want to run it for 10's of seconds, or longer, then you need to ballast it to reduce input current, which will greatly reduce output current. The 50KV - 400ma "full output" rating is really only good for one or two seconds, at most.
   
  Regards,
  Herr Zapp

Robert Davies <robert@xxxxxxxxxx> wrote:
  Hello All, In my area here in Florida scrap metal prices are so high it 
is basically impossible to find anything in the low budget or free 
arena. It looks like I will have to buy a transformer. Which is ok by me 
I just don't want to get stung. My question is what price range should I 
be looking to pay for a suitable transformer. I found one on ebay 
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180271844951&ssPageName=ADME:X:AAQ:US:1123 


Any advise would be most appreciated.

Thanks
Rob



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