Author Topic: Mysterious Chinese HV capacitors  (Read 672 times)

Offline MRMILSTAR

  • High Voltage Engineer
  • ****
  • Posts: 201
  • 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 Engineer
  • ****
  • Posts: 449
  • Karma: +25/-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 Engineer
  • ****
  • Posts: 201
  • 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: 27
  • Karma: +1/-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: Little Bee B Field / Current Probe
[General Chat]
Weston
Today at 07:27:18 AM
post Re: Drsstc tank Cap testing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Weston
Today at 07:02:44 AM
post Drsstc tank Cap testing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
oneKone
Today at 05:56:46 AM
post Re: Easy to build Polyphonic MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
Today at 12:03:47 AM
post Re: Little Bee B Field / Current Probe
[General Chat]
station240
July 13, 2020, 01:08:35 PM
post Re: Server PSU Hack - HP DPS-800GB A, 12VDC 1000W
[Electronic Circuits]
rikkitikkitavi
July 13, 2020, 08:30:46 AM
post Re: Capacitors and arcs
[Beginners]
Paradox
July 13, 2020, 01:59:09 AM
post Re: Easy to build Polyphonic MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
TMaxElectronics
July 13, 2020, 01:20:59 AM
post Re: compact midi interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
TMaxElectronics
July 12, 2020, 05:06:10 AM
post Re: Little Bee B Field / Current Probe
[General Chat]
Steve Ward
July 11, 2020, 10:23:24 PM
post Re: DRSSTC with litz-wire primary and 40 x TO247 IGBT H-Bridge
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
July 11, 2020, 09:36:02 PM
post Re: Server PSU Hack - HP DPS-800GB A, 12VDC 1000W
[Electronic Circuits]
Mads Barnkob
July 11, 2020, 07:36:23 PM
post Re: Server PSU Hack - HP DPS-800GB A, 12VDC 1000W
[Electronic Circuits]
Fumeaux
July 11, 2020, 04:45:18 PM
post Server PSU Hack - HP DPS-800GB A, 12VDC 1000W
[Electronic Circuits]
Mads Barnkob
July 11, 2020, 01:26:41 PM
post Re: Little Bee B Field / Current Probe
[General Chat]
Twospoons
July 11, 2020, 07:53:04 AM
post Little Bee B Field / Current Probe
[General Chat]
Weston
July 11, 2020, 06:37:03 AM
post Re: PCB etching, DIY (chemistry mostly)
[Printed Circuit Board]
klugesmith
July 11, 2020, 04:18:29 AM
post Re: PCB etching, DIY (chemistry mostly)
[Printed Circuit Board]
Twospoons
July 11, 2020, 01:35:07 AM
post Re: PCB etching, DIY (chemistry mostly)
[Printed Circuit Board]
klugesmith
July 10, 2020, 11:35:05 PM
post Re: Capacitors and arcs
[Beginners]
Morvandium
July 10, 2020, 11:10:57 PM
post Re: PCB etching, DIY (chemistry mostly)
[Printed Circuit Board]
Morvandium
July 10, 2020, 11:06:07 PM
post Re: Capacitors and arcs
[Beginners]
k42
July 10, 2020, 08:53:06 PM
post Re: XRay Tank- any ideas about what is inside
[Transformer (Ferrite Core)]
HighVoltageRulezz
July 10, 2020, 07:20:48 PM
post Re: Why is Auto-transformer (variac) called transformer??
[Beginners]
Morvandium
July 10, 2020, 04:45:43 PM
post Re: Cathodes in Compact Fluorescent Lamps
[Light, Lasers and Optics]
T3sl4co1l
July 10, 2020, 10:57:29 AM
post Re: Configuration of a half bridge.
[Electronic Circuits]
hammertone
July 10, 2020, 08:55:30 AM
post Re: Configuration of a half bridge.
[Electronic Circuits]
johnf
July 10, 2020, 08:48:33 AM
post Re: Cathodes in Compact Fluorescent Lamps
[Light, Lasers and Optics]
davekni
July 10, 2020, 07:00:13 AM
post Re: Configuration of a half bridge.
[Electronic Circuits]
davekni
July 10, 2020, 06:57:36 AM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
davekni
July 10, 2020, 05:44:54 AM
post Re: Configuration of a half bridge.
[Electronic Circuits]
johnf
July 09, 2020, 09:23:38 PM
post Re: Easy to build Polyphonic MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
July 09, 2020, 09:09:08 PM
post Re: Cathodes in Compact Fluorescent Lamps
[Light, Lasers and Optics]
klugesmith
July 09, 2020, 07:00:49 PM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
TMaxElectronics
July 09, 2020, 02:33:38 PM
post Re: Configuration of a half bridge.
[Electronic Circuits]
hammertone
July 09, 2020, 12:16:32 PM
post Re: Configuration of a half bridge.
[Electronic Circuits]
hammertone
July 09, 2020, 11:46:10 AM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
Twospoons
July 09, 2020, 10:56:18 AM
post Re: Configuration of a half bridge.
[Electronic Circuits]
johnf
July 09, 2020, 08:37:52 AM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
klugesmith
July 09, 2020, 06:45:18 AM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
TMaxElectronics
July 09, 2020, 02:36:22 AM
post Re: Configuration of a half bridge.
[Electronic Circuits]
Mads Barnkob
July 08, 2020, 09:43:20 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Morvandium
July 08, 2020, 09:33:35 PM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
johnf
July 08, 2020, 09:23:14 PM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
klugesmith
July 08, 2020, 09:16:42 PM
post Re: Configuration of a half bridge.
[Electronic Circuits]
johnf
July 08, 2020, 09:00:04 PM
post Re: Configuration of a half bridge.
[Electronic Circuits]
Mads Barnkob
July 08, 2020, 04:25:53 PM
post Re: Configuration of a half bridge.
[Electronic Circuits]
ElectroXa
July 08, 2020, 10:03:25 AM
post Re: Configuration of a half bridge.
[Electronic Circuits]
hammertone
July 08, 2020, 08:39:10 AM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
Twospoons
July 08, 2020, 08:34:02 AM
post Re: Measuring LED efficiency
[Light, Lasers and Optics]
davekni
July 08, 2020, 04:39:10 AM

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 
SimplePortal 2.3.6 © 2008-2014, SimplePortal