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Re: [TCML] mmc cap protection by spark-gaps-any ideas?



Sorry I should have been clearer. I was tired (2am) 
I used some "bulk" resistors that were available at the time and they were NOT that cheap. (added expenses gas charge and 14.5% tax.) Yes I did notice a drop in output, maybe 4-6 inches. (maybe it was the resistors? I don't know but according to the formula I must have had very bad or poorly labeled resistors.) I never went back to using them. After I got rid of the resistors I noticed a little increase.  --- 
I hope that makes a little bit more sense now ? 
 
  I agree, Matt  it is ideal to have the added safety. Again if I need to make any changes between firings I discharge the capacitors manually.   

Again sorry for the confusion.


----- Original Message -----
From: mddeming@xxxxxxx
Date: Tuesday, August 19, 2008 12:42 pm
Subject: Re: [TCML] mmc cap protection by spark-gaps-any ideas?
To: tesla@xxxxxxxxxx

> Oops,
> I dropped a term, Sorry. 
> P=E^2/R=12,000x12,000/200,000,000=144/200=720mw/string,
> or 1.44W out of 2.88KW, or 0.05%. Sorry for the carelessness, 
> but it 
> still makes the claim of waste seem pretty farcical.
> 
> Matt D.
> 
> -----Original Message-----
> From: mddeming@xxxxxxx
> To: tesla@xxxxxxxxxx
> Sent: Mon, 18 Aug 2008 4:42 pm
> Subject: Re: [TCML] mmc cap protection by spark-gaps-any ideas?
> 
> 
> Hi Connor, 
>  
> Congratulations on not zapping yourself, YET. 
> With resistors running about 1-2 cents each in bulk, I can't see 
> that 
> it is a major expense for added safety. 
> Many older coilers (30-yr experience+) believe they got to be 
> that way 
> by using both a J-stick AND discharge resistors. 
> Using 20 10-meg resistors would "waste" three MILLIWATTS per string. 
> I find it hard to believe that you could really notice a loss of 
> 0.006 
> watts out of 2880 watts total. 
> That's about 0.0002%! Seems like a very small price to pay for 
> the 
> added safety. 
>  
> Matt D. 
>  
> -----Original Message----- 
> From: CONOR WHYTE <cjwhyte@xxxxxxx> 
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx> 
> Sent: Sun, 17 Aug 2008 11:37 pm 
> Subject: Re: [TCML] mmc cap protection by spark-gaps-any ideas? 
>  
>  
> I don't use resistors on my MMC. I find these waste energy and 
> cut down 
> on my 
> spark length. I  use CDE 942C series 1.6Kvdc 680nF capacitors, I 
> use 20 
> per 
> string 34nF @ 32Kvdc 
> x2 . I run 12Kvac @ 240mA. I have been running my 
> MMC now 
> for 2 years and have had 0 problems.  
> Quite often many people are scared about residual charge in the 
> cap 
> bank this is 
> why people add the resistors. It bleeds charge away after the 
> unit is 
> turned 
> off. You can do this with a discharge wand MUCH cheaper. 
> Like I said I have never used them. It is a waste of energy.  
> If you feel like you want to protect your cap bank, I'd might 
> make an 
> extra gap 
> that one could adjust. 
> maybe say to be safe a 3.5cm gap 35Kv.  I would also make sure 
> the MMC 
> total DC 
> rating is around 3x that of the input voltage.  12Kvac -- 32-
> 36Kvdc. 
>  Another 
> factor I would also check is the tolerance rating of the 
> capacitors 
> most are 
> 5%... which is ok... CDEs on the other hand are 10% and can 
> handle much 
> more 
> voltage spikes. 
>   
>  
> ----- Original Message ----- 
> From: vatercox@xxxxxxx 
> Date: Monday, August 18, 2008 10:47 am 
> Subject: [TCML] mmc cap protection by spark-gaps-any ideas? 
> To: tesla@xxxxxxxxxx 
>  
> > Dear List 
> > I have 30 x 47nF polypropylene metal foil caps, each rated at 2 
> > kVDC 
> > which I intend to wire as three strings of 10 capacitors for 
> > approximately 14nF at 20kV DC. While normally each capacitor in 
> > an MMC 
> > would be protected by a 10- or m
> ore megohm high voltage resistor 
> > these 
> > have proved difficult to obtain (due to lack of demand?). In liu 
> > of 
> > this would it be possible to protect each cap with a miniature 
> > spark-gap -perhaps a pair of closely-positioned stiff wires 
> > connected 
> > to the capacitor leads notwithstanding the fact that 2 kV is 
> > usually 
> > regarded as a bit on the low side for satisfactory spark-gap 
> operation 
> > 
> > Jolyon Francis Vater-Cox 
> > 
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