Author Topic: Mysterious Chinese HV capacitors  (Read 254 times)

Offline MRMILSTAR

  • High Voltage Technician
  • ***
  • Posts: 118
  • Karma: +4/-0
  • Cedar Rapids, Iowa
    • View Profile
Mysterious Chinese HV capacitors
« on: October 15, 2019, 09:12:09 PM »
Has anyone used these capacitors in any projects? I have a 20-stage Marx generator that uses these capacitors and it seems to work fine with 12" sparks. I have been able to find out that they are metallized film polystyrene construction so they should be self-healing. I have the 2000 pF capacitance model but I have also seen a 3000 pF capacitance model. They are claimed to be rated for 30 KV. I may use these for a Cockroft-Walton voltage multiplier. I was also wondering if they would be good for tesla coil duty. I suspect not. The reason that they are so attractive is the price. They sell for about $2 on E-Bay. Here is an example E-Bay link.

https://www.ebay.com/itm/2000pF-30KV-DC-high-voltage-condenser-capacitor-for-marx-generator-hv-ham-rad-DM/273846620888?epid=9020951115&hash=item3fc287d2d8&_trkparms=ispr%3D1&enc=AQAEAAADMKvsXIZtBqdkfsZsMtzFbFsbX3WcW5fmB%2Fx7ZbaZTyexrltoT9Zyh679cvGbGwMYfnOzVcfPVaNgKYixjPpdJl0YwNeaSYUyV3otBZu3ZYDcVmPybi7BFy%2FqkKQ%2FXoJE1B58Hs5Tj1CBCPGp71SDQqnJANJyGaKGkGD3UH6GRGDoKnvqrn11vwktTOQJtVmPMdK7hH3NRVucDXxtUQxGjPvsZ5qO3GrqCyr7VxPr6Cn1jSMF9v8lPvSEllYdo6Nlw6EwkJ%2BuqnA%2FdTuKIiVFv6IVwC8DkrsXVPJxbYcvly8ui%2FeG%2BGsvmsK1r%2FiNIE3zz1d9OPlyebx%2FoP6AFdqizbhKjMM2s7a9x5lLi%2FACknZn80kRUMYaLP3L%2BmS0g5bmASQgTo1pSjtNUwv4Ei1%2BJKzkd4jzUeGb0ZKtSJL9a1rtOquNz%2BIXF6Q9imwLGTYs205qB9q3YCoJTYwpEmajnUV%2B9nt5U%2FVnV3lgaGwx1PfsUWUbI%2FvZ5e3Cd39%2BVX%2Fj6fh3y4EZijZ%2F2OhD%2FD0gR9pGV530LUTAg6L7%2B4QdGO9QH%2Fbs%2BR8WKcoTzXrdtbsq0Qnaw8E4uPzo4NYURtQoDklouTLld7itmAEPYKQ%2FOvJ656oGAnEf6v4DNBseFq0PBnImyiBrXr4HJMgrTBwZxazhCsNFgw90iTYhdemeKwQ0wG48tkvQ%2F7i8CrRkURjXGs7Ok1%2B8L6yxrusXrmRtlyR1y%2F8ShVe9grRIfyYNuzRFgWyXgNsH3JCC1HLiXY9vueXFa%2FJ9KlPiBacrcv9ojNXk00Z%2FaOojrrvTfsQWk13rqLW9NI6KhDLTLspcDMu0yYay9rGlTE9Y5GnCIKoOgDeUjmHZuyS%2BbpWgzmqDXwlOiRyiMFE1SNks9udhz6kXCBAe%2FJUEGQY5I3590%2F51yEHZAhP%2FlR4MGySdxQhKiE4UYEVZrgQ9yUs9Q0CB3dSOKNJyiRyBgg%2BLvGOB3HL%2FXgsKzRk%2FpqsgSinWcJMuLieharyJZaMnh3LLQ%2FJ%2FudGbaudBhyR06Qd%2B909Sjq9wsQr062lrMSP8rdU1mr4KkM%2Fgk8kKrkOssHGoEk3xJ3h0dw%3D%3D&checksum=273846620888c8316e1b54254e779cb82cf9e547cd63

Wow! That is certainly a long link.
Steve White
Cedar Rapids, Iowa
Retired electrical engineer

Offline davekni

  • High Voltage Technician
  • ***
  • Posts: 130
  • Karma: +5/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: Mysterious Chinese HV capacitors
« Reply #1 on: October 16, 2019, 03:33:52 AM »
These look exactly like the polystyrene capacitors I purchased on EBay 3 or 4 years ago.  They are very-low leakage, great for voltage-multiplier use.  However, they are foil, and have random tiny bubbles included, which form corona discharges in AC or pulse (Marx) use.  For low-frequency Marx use, they work OK.  My Marx generator recharges up to 120 times per second (plays low-register tunes).  In that use, they last a few minutes at most.  Same for AC (Tesla coil) use.
David Knierim

Offline MRMILSTAR

  • High Voltage Technician
  • ***
  • Posts: 118
  • Karma: +4/-0
  • Cedar Rapids, Iowa
    • View Profile
Re: Mysterious Chinese HV capacitors
« Reply #2 on: October 16, 2019, 05:40:55 AM »
That's sort of what I thought. My Marx generator only produces a 12" spark about every 2 seconds although it is a very juicy spark. None of the caps have ever failed.

I have some spares of these capacitors. I have looked at the mounting of the leads and I can't quite see what is going on because even though the ends are clear, they are shaped sort of like a Fresnel lens which distorts what I can see. There appears to be schoopage of some sort of silvery material on each end which I assume is a conductor. There is one large axial lead on each end which makes sense. There is also an additional lead on each end made of very fine gauge wire. This smaller lead is connected to the larger lead and the other end appears to connect to the foil. I can't tell if the larger lead is connected to the schoopage or not. If not, then the entire current load must carried by the small leads. Maybe the large lead is just for mechanical strength for mounting. Some of the descriptions state that the large leads are for mechanical mounting strength but they don't say explicitly that they are also connected to the schoopage so that they can also handle the current.

Since they only cost $2 apiece, I'm tempted to sacrifice one of my spares by cutting those small leads to find out if I can charge the capacitor through only the large axial leads.

I've never seen a capacitor with a large lead and a much smaller lead on each end before. The construction of these capacitors are some of the reasons that these are a mystery to me.
« Last Edit: October 16, 2019, 05:48:19 AM by MRMILSTAR »
Steve White
Cedar Rapids, Iowa
Retired electrical engineer

Offline ElectroXa

  • High Voltage Enthusiast
  • *
  • Posts: 10
  • Karma: +0/-0
    • View Profile
Re: Mysterious Chinese HV capacitors
« Reply #3 on: October 16, 2019, 08:35:30 PM »
Hi
I've seen them on EBay, ant these caps were interesting for me, for a voltage multiplier
But partial discharges are a problem as davekni said, because  I planned to use them at 75 kHz and ~15 kV .
Does anyone already tested them at high frequency, to have a feedback before buying them ?

thanks a lot  :)
« Last Edit: October 16, 2019, 08:41:25 PM by ElectroXa »

Offline Experimentonomen

  • High Voltage Enthusiast
  • *
  • Posts: 6
  • Karma: +1/-0
    • View Profile
Re: Mysterious Chinese HV capacitors
« Reply #4 on: October 16, 2019, 08:41:05 PM »
Looks like inductive wind, so no good for anything above the audio range.

High Voltage Forum

Re: Mysterious Chinese HV capacitors
« Reply #4 on: October 16, 2019, 08:41:05 PM »

 


* Recent Topics and Posts

post Re: How do you keep in contact with forum people...?
[General chatting]
Mads Barnkob
Today at 09:31:58 AM
post Re: My first DRSSTC on bricks
[Dual Resonant Solid State Tesla coils]
johnf
Today at 07:56:39 AM
post Re: Royer oscillator (ZVS) driven Jacob's ladder, E80 core transformer
[Transformer (ferrite core)]
AndreiRS
Today at 03:59:49 AM
post How do you keep in contact with forum people...?
[General chatting]
AndreiRS
Today at 03:23:31 AM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
klugesmith
Today at 12:16:53 AM
post Re: My first DRSSTC on bricks
[Dual Resonant Solid State Tesla coils]
Laci
December 12, 2019, 08:35:24 PM
post Re: How To Make a Stencil For Spray Paint With Cheap Hand Tools
[General chatting]
johnf
December 12, 2019, 07:53:35 PM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
John123
December 12, 2019, 02:52:58 PM
post Re: Royer oscillator (ZVS) driven Jacob's ladder, E80 core transformer
[Transformer (ferrite core)]
John123
December 12, 2019, 02:42:19 PM
post Re: Full bridge much "weaker" than half bridge?
[Solid state Tesla coils]
nick
December 12, 2019, 11:17:36 AM
post Re: Royer oscillator (ZVS) driven Jacob's ladder, E80 core transformer
[Transformer (ferrite core)]
davekni
December 12, 2019, 04:51:08 AM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
davekni
December 12, 2019, 04:26:22 AM
post Re: How To Make a Stencil For Spray Paint With Cheap Hand Tools
[General chatting]
AndreiRS
December 12, 2019, 01:21:35 AM
post Re: Using same winding on separate rails?
[Transformer (iron core)]
Twospoons
December 11, 2019, 10:49:04 PM
post Re: A dynamical arc model v2
[Dual Resonant Solid State Tesla coils]
Uspring
December 11, 2019, 05:28:46 PM
post Re: Full bridge much "weaker" than half bridge?
[Solid state Tesla coils]
Fumeaux
December 11, 2019, 03:11:42 PM
post Re: Royer oscillator (ZVS) driven Jacob's ladder, E80 core transformer
[Transformer (ferrite core)]
John123
December 11, 2019, 02:22:10 PM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
John123
December 11, 2019, 02:09:19 PM
post Full bridge much "weaker" than half bridge?
[Solid state Tesla coils]
nick
December 11, 2019, 01:10:57 PM
post Re: Possible use for large inductor (laminated core)
[Transformer (iron core)]
kamelryttarn
December 11, 2019, 08:48:36 AM
post Re: SGTC MK1 - An Accomplishment in Progress
[Spark gap Tesla coils]
davekni
December 11, 2019, 06:08:48 AM
post Re: SSTC low voltage at gate transformer and heating drivers
[Solid state Tesla coils]
davekni
December 11, 2019, 05:38:17 AM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
davekni
December 11, 2019, 05:01:31 AM
post Re: Using same winding on separate rails?
[Transformer (iron core)]
John123
December 11, 2019, 01:52:43 AM
post Re: Using same winding on separate rails?
[Transformer (iron core)]
klugesmith
December 11, 2019, 01:41:04 AM
post Re: Worlds Weirdest Microwave Oven, From A Weapons Factory - The Husqvarna Cupol
[Transformer (iron core)]
klugesmith
December 11, 2019, 01:37:13 AM
post Re: Using same winding on separate rails?
[Transformer (iron core)]
John123
December 11, 2019, 01:19:58 AM
post Re: SGTC MK1 - An Accomplishment in Progress
[Spark gap Tesla coils]
jturnerkc
December 11, 2019, 01:14:32 AM
post Re: Using same winding on separate rails?
[Transformer (iron core)]
klugesmith
December 11, 2019, 01:04:08 AM
post Re: SSTC low voltage at gate transformer and heating drivers
[Solid state Tesla coils]
babass
December 10, 2019, 11:24:50 PM
post Using same winding on separate rails?
[Transformer (iron core)]
John123
December 10, 2019, 10:52:50 PM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
John123
December 10, 2019, 03:35:40 PM
post Re: Why did 4HV die??
[General chatting]
John123
December 10, 2019, 03:21:07 PM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
Mads Barnkob
December 10, 2019, 03:04:28 PM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
John123
December 10, 2019, 02:57:45 PM
post Re: Possible use for large inductor (laminated core)
[Transformer (iron core)]
kamelryttarn
December 10, 2019, 11:23:48 AM
post Re: SGTC MK1 - An Accomplishment in Progress
[Spark gap Tesla coils]
Mads Barnkob
December 10, 2019, 10:27:54 AM
post Re: Worlds Weirdest Microwave Oven, From A Weapons Factory - The Husqvarna Cupol
[Transformer (iron core)]
Mads Barnkob
December 10, 2019, 10:20:17 AM
post Re: Possible use for large inductor (laminated core)
[Transformer (iron core)]
Mads Barnkob
December 10, 2019, 10:16:32 AM
post Re: SGTC MK1 - An Accomplishment in Progress
[Spark gap Tesla coils]
davekni
December 10, 2019, 06:04:28 AM
post Re: Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
davekni
December 10, 2019, 05:28:54 AM
post Re: Possible use for large inductor (laminated core)
[Transformer (iron core)]
davekni
December 10, 2019, 04:12:29 AM
post Duty cycle when driving a CRT TV flyback transformer
[Transformer (ferrite core)]
John123
December 09, 2019, 10:52:59 PM
post Replacement guide for Windows Media Center
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
MRMILSTAR
December 09, 2019, 08:29:16 PM
post Re: Sense coil fabrication?
[Induction launchers, coil guns and rails guns]
Uspring
December 09, 2019, 04:23:33 PM
post Re: Possible use for large inductor (laminated core)
[Transformer (iron core)]
MRMILSTAR
December 09, 2019, 03:59:02 PM
post Re: SGTC MK1 - An Accomplishment in Progress
[Spark gap Tesla coils]
jturnerkc
December 09, 2019, 03:41:42 PM
post Possible use for large inductor (laminated core)
[Transformer (iron core)]
kamelryttarn
December 09, 2019, 09:43:11 AM
post Re: SGTC MK1 - An Accomplishment in Progress
[Spark gap Tesla coils]
davekni
December 09, 2019, 12:53:57 AM
post Re: CW multiplier resistor string suggestions
[Voltage Multipliers]
davekni
December 08, 2019, 09:57:51 PM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30