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Re: Awesome Quarter Shrinking Capacitors on EBAY



Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net> 

John,

You might want to measure it with a Capacitance meter.  Or, time how long 
it takes to charge and then back figure the C based on the charging 
current. O charge it up and discharge it through a suitable power resistor 
and calculate the RC time constant to find C. Since the cap is rated for 
4000 VAC, it might have been used in industrial induction heating or as 
part of a mercury or sodium vapor ballast (quite likely). Does it look 
similar to the LK series from Plastic Capacitors? See: 
http://www.plasticcapacitors-dot-com/typelk.html

Here's the reality -  Based on the physical size it's definitely a 4 uF 
capacitor. With a 4000 VAC rating, your cap can withstand at least 5600 
VDC. If the capacity was indeed 4,000 uF, the cap would have an energy 
storage capability of almost 64,000 joules. Capacitor technology has simply 
not evolved to the point where you can pack this level of electrostatic 
energy density in a package the size of a Simpson meter.

BTW, the disruptive discharge from a 4 uF 4,000 volt cap does make one HECK 
of a bang. A 10,000 joule discharge sounds more like a stick of dynamite 
going off. Although your cap may "only" store 64 joules, it can kill you 
just as dead as a 10,000 joule cap.

Best regards,

-- Bert --
-- 
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We specialize in UNIQUE items! Coins shrunk by Ultrastrong Fields,
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Tesla list wrote:
>Original poster: John <fireba8104-at-yahoo-dot-com>
>HI,
>Jim
>It is definitely MFD = 1E-3 Farad. This may be a custom cap, considering 
>the branch of electronics this man is in. I blow up wire and precises of 
>metal with this thing. I have to use a plate to discharge it because it 
>destroys any resistors I try to use.
>I wish I knew where he got this cap from. If I did there is no drought I 
>would buy more.
>I have only come up with two sources that sell similar caps 1.) 
><http://www.plasticcapacitors-dot-com/>http://www.plasticcapacitors-dot-com and 
>2.) <http://www.herbach-dot-com/>www.herbach-dot-com. Note: I don't think this cap 
>came from either of these sources I am only presenting them as some 
>indirect proof that caps with voltage and capacitance ratings do exist at 
>around this size.  I'll see if I can post some pictures
>Tesla list <tesla-at-pupman-dot-com> wrote:
>Original poster: "Jim Lux"
>Almost certainly MFD = 1E-6 Farad.. i.e. microfarad. millifarad is almost
>never used as a unit.. microfarad, nanofarad, picofarad and micromicrofarad
>I've seen..
>Oil filled metal can really starts to look like 4 microfarads at 4 kV...
>----- Original Message -----
>From: "Tesla list"
>To:
>Sent: Tuesday, October 07, 2003 8:04 PM
>Subject: Re: Awesome Quarter Shrinking Capacitors on EBAY
>
>  > Original poster: John
>  >
>  > Hello,
>  > This capacitor is not a electrolytic or a cap bank.
>  > It is in an oil filled metal can with large white ceramic insulators.
>  > I am not sure what kind of dielectric, but I believe it to be a type of
>  > plastic.
>  > The exact wording on the side of the cap reads as follows:
>  > KN128
>  > 4MFD
>  > 4000VAC
>  > I was unsure as to weather this was Milli or Micro. My hopes were
>confirmed
>  > when I asked the man who gave it to me, a professional electrical
>  > engineer.(0.004). I think it's from
>  > http://www.plasticcapacitors-dot-com, after
>  > all he is a customer.
>  > Cheers,
>  > John
>  >
>  > Tesla list wrote:
>  > Original poster: "Jim Lux"
>  >
>  > Indeed.. you're right, I missed the missing u... But, then, a 4000 uF cap
>at
>  > 4kVAC rating.. Hmmm. maybe in the form factor cited, but not going to be a
>  > high current device. Almost certainly a stack of electrolytics, which then
>  > casts doubt on the VAC rating, as opposed to VDC...
>  > Say, then, two 8000 uF 4kV DC electrolytics in series? I've got some
>  > 250,000 uF 400 V electrolytics in a form factor comparable to what's
>  > quoted.. But, to g! et 4 kV, means 10 in series, for 25 uF... For 4kV AC,
>  > that's 12 uF, and would be a LOT bigger than a Simpson, but, not orders of
>  > magnitude.
>  >
>  >
>  > I think though, that we could agree that this is NOT something with high
>  > pulse current capability.
>  >
>  >
>  > ----- Original Message -----
>  > From: "Tesla list"
>  > To:
>  > Sent: Fri! day, October 03, 2003 8:35 PM
>  > Subject: Re: Awesome Quarter Shrinking Capacitors on EBAY
>  >
>  >
>  > > Original poster: Mddeming-at-aol-dot-com
>  > >
>  > > In a message dated 10/3/03 6:42:16 PM Eastern Daylight Time,
>  > > tesla-at-pupman-dot-com writes:
>  > > Original poster: Jim Lux
>  > >
>  > > At 03:47 PM 10/3/2003 -0600, you wrote:
>  > > >Original poster: John
>  > > >I have a 0.004F cap rated at 4000VAC (32,000 jolues) that is only a
>bit
>  > > >smaller than my simpson 260 multimeter.
>  > >
>  > &g!
>t; That's 32 millijoules, not 32kJ... .004 * 4*4/2 = 32E-3...
>  > >
>  > > Look again. he said 0.004F NOT .004 uF! If he's right, your calculation
>is
>  > > off by 10e6
>  > >
>  > > Matt D.
>  > >
>  >
>
>.