Re: Building a 4"

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Jeremy,

At 12:28 AM 10/7/2002 -0700, you wrote:
>Hi,
>
>I'm an avid electronics adventurist making my
>first coil. Those capacitor-diode voltage multipliers
>just don't do it for me anymore :)

Check this one out:))

http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&item=1774441199

>
>Anyway, the coil I am building is a typical 4.5"
>secondary. I have completed the primary (16 turns .25"
>copper fridge tube .25" apart, 30 degree inverse cone)
>- so far so good. 

Neat!

>
>Now I have my questions:
>
>I am designing this to use a 15Kv/60mA neon
>transformer. I found a place to get one new
>for $150. I'm not sure if this is a good
>price for new, me thinks its kind of expensive.
>I've called all my local neon shops (about 3) 
>and they don't have any old ones to give me. 

I paid about $120 for a new one plus $30 to have it shipped a few years
ago.  Ebay has them sometimes but shipping is pretty rough for something so
heavy.  People do find them free or they "fix" old ones but for the money
and all, $150 for a new NST in hand is not too terrible.  If you want to
search and scrounge for hours on end you can probably find one far cheaper.
 a lot depends on if it is worth it to "you" or not ;-)

>
>Does anyone on this list have a better source
>for cheaper neons, preferably new ones? 

Maybe someone has a better deal...

>
>I tried building a few capacitors already, and
>most of them are a pain in the butt. (Saltwater,
>rolled aluminum flashing, etc...) 

Make an MMC.

>
>I've decided to go MMC. My capacitor research
>tells me that metal-polyethylene are the ones to 
>use. 

No!  You want metal foil electrode "polypropylene" high-voltage
high-current.  150uF 2000Volt Cornell-Dubileir as sold by Chris Boden or
www.rell-dot-com are what you want.  The usage chart is at:

http://hot-streamer-dot-com/temp/MMCcapSales.gif

http://hot-streamer-dot-com/TeslaCoils/MMCInfo/GeekCaps/GeekCaps.htm

I would get 16nF not 10nF.  that is far safer for your $150 NST.  You may
also want a good solid NST protection filter like this one:

http://hot-streamer-dot-com/TeslaCoils/Misc/NSTFilt.jpg

A 15 amp input fuse too.  Then, the chances of blowing an NST are pretty
near zero...  If you have a sync rotary gap, you can go to 28nF (0.001uF =
1nF).

>At 15kV/60mA, I figure a .01 ufd will 
>give me the most bang. I've found a list of 
>known working MMC capacitors, some of them have
>their voltages rated in AC while others are DC.
>(I looked up the technical specs of some of them.)
>It makes it difficult to figure out how many of
>each I'll need because those rated in DC volts
>have quite a substantial reduction in the 
>rating in AC volts. (RMS?)

In our case, we can use the DC ratings.  Very short duty cycle pulses....
See the tips and stuff at:

http://hot-streamer-dot-com/TeslaCoils/MMCInfo/mmcinfo.htm

>
>Does anyone have a recommendation as to a) 
>what combination of ufd/voltage/qty and b) a good
>soure to get them? (DigiKey is WAY expensive, there
>has to be somewhere else cheaper.) I'd like to play it
>safe, spend the extra money for more capacitors and
>NOT have them explode. :)

Not sure who has the best deal.  Chris or Rell, but they both got them ;-))

>
>Other than that, I'm off to winding my secondary :)

Cheers,

	Terry

>
>TIA, 
>
>-Jeremy
>