Re: [TCML] Looking for Pole Pig Capacitors

[jhowson4@xxxxxxxxxxx]

Thats the same problem i am  currently having, sourcing a capacitor. ugg 



I am slowing making a DC coil using the dual gapped charging system Steve young demonstrated a while ago, I am planning on throughly analysing the system and optimizing it if I can ever  find a capacitor. 

Its using a 14.4kv PT,  overdriven and recitifed producing 23.75 kv peak.  Doubled from the chargng inductor means 47.5kv peaks that the tank cap needs to be subjected to.  M eaning a 100kv + cap rating is necessary.  uggg  if only maxwells were not so expensive. 



I am to the point now where I am thinking about aquring another 7200V pt just so the voltage is lower and I can utilize more easily found caps/more easily make my own. 



For a filter cap I am using a huge array of MOT caps (thank you Steve Young),  its rated for 25kv and while I don't  have the actual capacitance off hand, it is large enough to have a ripple voltage below .1%.   Just figured I would throw that out their while you guys were talking about filter caps and the like.   


I am currently in the process of making a website to post info and pictures of this coil, if any one has good suggestions for a cheap site host, an off list message would be appreciated. 


Thanks, 
John "Jay" Howson IV 


"Why thank you, I will be happy to take those electrons off you hands."  

----- Original Message -----
From: "Travis Tabbal" <travis@xxxxxxxxxx> 
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> 
Sent: Tuesday, November 29, 2011 10:54:44 AM 
Subject: Re: [TCML] Looking for Pole Pig Capacitors 

On Tue, Nov 29, 2011 at 8:17 AM, Roger Smith <rwsmith@xxxxxxxxxxxxxx> wrote: 

> 
> Travis,   When I first built my big DC resonant charging Tesla coil I was 
> using 7200 volt pole pig with a voltage double and I used a 5uF filter 
> capacitor.  The important thing about your filter capacitor is that it 
> protects the diodes in your voltage doubler.  If you have a little ripple 
> in your supply voltage you wont notice it.    One nice thing about about 
> the voltage doubler is that you can regulate the output by changing the 
> size of the shifter capacitor.   Most people don't have variacs that can 
> handle a pole pig system these days. 
> 
>  As for the voltage doubling effect at the primary capacitor, you don't 
> have to worry about that.     The same thing goes on with an AC system to 
> some degree and remember the peak voltage of 14.5 KV transformer is 20.5 KV 
>  .       I have upgraded from the 7.2 KV  pole pig to a 19.5 KV pole pig 
> that I am using with a full wave rectifier and a 1 uF filter capacitor and 
> I haven't blown any capacitors yet and that's running it with 230V going 
> directly to the pig with no ballasting !      I do believe I'm on thin ice 
> though.   I haven't put on a lot of run time running it this way. 
> 
>  As for the deQing diode , I would say you will probably want that .  Some 
> smaller DC resonant Tesla coils I have built didn't need them but my big 
> one dose need it.     I haven't done much running with low break rates. 
> My big coil runs at about 400 breaks per second but on one of the first DC 
> coils I ever built I got the longest sparks running at a real low break 
> rate because I had a limited power supply .   It was some kind of a MOT 
> with voltage doubler arrangement. 
> 
> Roger 
> 


Roger, 


Thanks for the great info. So your current system uses a 20KV pig.. So the 
coil primary sees 40+KV? No problems with insulation and such at that 
voltage? What is your primary cap's voltage rating? For the filter cap, we 
don't need anything particular, right? So doorknob caps and such will work? 
And I need to rate them for the peak voltage from the transformer, so in my 
case running at 14.4KV, 20KV or so. Does the charging inductor need to be 
anything particular as far as core material and such? 

Come to think of it, I'm sure a lot of my questions would be answered fine 
if you have a site documenting your setup? 
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