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Re: Awesome Quarter Shrinking Capacitors on EBAY
Original poster: Kevin Christiansen <kevinc-at-crystalcanyon-dot-com>
If you don't have a capacitance meter, try this simple experiment...
The capacitive reactance of a 4 microfarad cap is 663 ohms at 60 Hz.
The capacitive reactance of a 4 millifarad cap is 0.663 ohms at 60 Hz.
Put your capacitor in series with an AC amp meter and put that
directly accross the secondary winding of a 12 volt AC transformer.
Now use ohm's law: current = voltage / resistance (capacitive reactance).
If something like 18 mA of current flows, it's 4 microfarad.
If something like 18 Amps of current flows, it's 4 millifarad.
(In theory, you would need a stiff (beefy) transformer for the
second case, but since the cap is obviously 4 uF, just about
any 12 VAC transformer can supply the 18-20 mA required...)
Let us know when you do the experiment.
- Kevin Christiansen
At 08:54 PM 10/8/03 -0600, you wrote:
>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 --
>--
>--------------------------------------------------------------------
>We specialize in UNIQUE items! Coins shrunk by Ultrastrong Fields,
>Lichtenberg Figures (electrical discharges in acrylic), & Scarce OOP
>Technical Books. Stoneridge Engineering -- http://www.teslamania-dot-com
>--------------------------------------------------------------------
>
>
>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.
>> > >
>> >
>>
>>.
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