That sounds like they are talking about the main leads and them being larger and strong to physically support the cap.
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________________________________
From: Tesla <tesla-bounces@xxxxxxxxxx> on behalf of Douglas Johnson <doug379306@xxxxxxxxx>
Sent: Wednesday, November 7, 2018 9:39:29 AM
To: tesla@xxxxxxxxxx
Subject: Re: [TCML] Mystery HV capacitors
I think this will solve the connecting wire mystery. I believe the term
"FEET" is referring to the wires!
This is from the add!
This capacitor is used in DC pulse circuits such as filtering and double
voltage in electronic equipment, such as negative ion generators and small
electrostatic devices.
Our shop for lovers of Marx generator customization of high voltage
capacitor,2000pF 30KV，Large capacity, arc thick, the more important is The
capacitor of the Marx generator is easily broken from the root when it is
fixed, Unable to solder the leads, Our custom capacitors are individually
added with two thick fixed feet, Don't have to worry about breaking when
fixed !
*Package Contents *
100% Brand New
1 x 30kV DC 2000pF High Voltage Film Capacitor
On Wed, Nov 7, 2018 at 10:22 AM Douglas Johnson <doug379306@xxxxxxxxx>
wrote:
> Hi, I have been thinking about building a "MARX" with these caps. Can
> someone recommend a suitable Resister for a 10 stage Marx using these caps?
> Doug
>
> On Tue, Nov 6, 2018 at 9:10 PM Steve White <steve.white1@xxxxxxxxx> wrote:
>
>> Hi Bert,
>>
>> Obvious cheap Chinese stuff. I found a Chinese vendor that will sell 20
>> of these at $1.50 each including shipping! My suspicion goes up when I can
>> get one of these 2000 pF 30 KV capacitors for just $1.50. How good can they
>> be? They advertise them as being used for DC filtering, electrostatic air
>> fresheners, Cockroft-Walton voltage multipliers, and the like. I think they
>> would be OK to use for these applications. They also appear to work well
>> for Marx generators even though that is a pulsed power application.
>>
>> I did look at the capacitors a little closer today because I have one
>> from my Marx generator. As well as I can see through the translucent
>> plastic case, it does appear that the ends of the foil roll have been
>> sprayed with some kind of metallic substance which is in line with the way
>> these capacitors are supposed to be made. The mystery is why the tiny wires
>> are there along with the much larger axial leads. The tiny wires appear to
>> be attached to the foil at the outer circumference of the roll and the
>> inner circumference as you described. However it also appears that the
>> large axial leads are also attached to the metallic coating end caps at the
>> center. So it looks like they attached large and small leads to the end
>> caps. Weird.
>>
>> Steve White
>> Cedar Rapids, Iowa
>>
>> ----- Original Message -----
>> From: "Bert Hickman via Tesla" <tesla@xxxxxxxxxx>
>> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
>> Sent: Monday, November 5, 2018 12:09:03 PM
>> Subject: Re: [TCML] Mystery HV capacitors
>>
>> Hi Steve,
>>
>> Most metalized-film capacitors spray a layer of zinc onto the ends of
>> the capacitor. The zinc makes a gas-tight connection with the evaporated
>> aluminum metalization at the end of the capacitor roll. The zinc cover
>> layer forms a base that's then soldered to the axial copper end lead.
>> This construction technique creates a mechanically and electrically
>> robust, low inductance capacitor capable of handling high pulse
>> currents. However, high-current stress testing often shows that the
>> zinc-aluminum interface is the weakest link during repetitive pulse
>> discharge testing.
>>
>> In the images shown for the eBay capacitor, it looks like this
>> particular manufacturer may have taken a shortcut by using small wires
>> to make connection to the ends of the capacitor roll instead of using
>> sprayed metal layers. The wire appears to be physically pressed against
>> the bare end of the capacitor roll and perhaps held in place by the
>> molded outer case. Although this might work for low-current
>> (Cockcroft-Walton or DC filter) applications (at least for a while), it
>> will likely arc, and prematurely fail, under repetitive high-current
>> discharges seen in Marx or TC use.
>>
>> If you can't identify the manufacturer, and can't get any spec sheets,
>> that's not a good sign. You get what you pay for... and with no-name
>> Chinese sources, less.
>>
>> Bert
>>
>> Steve White wrote:
>> > Does anyone know anything about these capacitors? They are unbranded
>> shipped from China. The only markings are:
>> >
>> > CB80
>> > 2000 pF
>> > 30 KV
>> >
>> > I have searched all over the internet and I can't find out anything
>> else. I know they are plastic film capacitors. I have a Marx generator made
>> from these capacitors and they seem to work well for that purpose. They
>> have an odd construction feature. They have nice solid axial leads and the
>> leads seem to go all the way into the foil. But if you look closely, each
>> lead has a tiny wire, much smaller than the axial lead, connected to it
>> leading back into the capacitor. You can't really see it on the picture. I
>> am wondering if the large leads are just for good mechanical support and
>> the tiny leads are what is actually carrying the current into the foil. If
>> so, I can't imagine these tiny leads are going to carry much current. I am
>> wondering how well these might work in a small tesla coil. My hunch is not
>> very well. My interest in them is because the price is inexpensive.
>> >
>> > Here is a link to some for sale on E-Bay.
>> >
>> >
>> https://www.ebay.com/itm/2000pF-30KV-DC-High-Voltage-Condenser-Capacitor-for-Marx-generator-HV-Ham-Radio/173570926164?epid=9020951115&hash=item2869a22654:g:4goAAOSw1Sdbtexc:rk:46:pf:0
>> >
>> > Steve White
>> > Cedar Rapids, Iowa
>> > _______________________________________________
>> > Tesla mailing list
>> > Tesla@xxxxxxxxxxxxxxxxxx
>> > https://www.pupman.com/mailman/listinfo/tesla
>> >
>> >
>>
>>
>> --
>> Bert Hickman
>> Stoneridge Engineering LLC
>> Woodridge, Illinois, USA
>> http://www.capturedlightning.com
>> +1 630-964-2699
>> ***********************************************************************
>> World's source for "Captured Lightning" Lichtenberg Figure sculptures,
>> magnetically "shrunken" coins, and scarce/out of print technical books
>> ***********************************************************************
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>>
>
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