Author Topic: CW multiplier resistor string suggestions  (Read 256 times)

Offline MRMILSTAR

  • High Voltage Technician
  • ***
  • Posts: 140
  • Karma: +4/-0
  • Cedar Rapids, Iowa
    • View Profile
CW multiplier resistor string suggestions
« on: December 07, 2019, 11:32:49 PM »
I need some suggestions on the HV current-limiting resistor string for my CW multiplier. Briefly, here is my proposed design.

* 14-stage design based on 28 TDK 1.7 nF doorknob capacitors rated at 30 KV
* Each diode string consists of three 20 KV 30 ma diodes in series
* To be powered by 1 or 2 flyback transformers in parallel driven by a ZVS circuit
* Current-limiting via HV resistor string, resistance TBD
* Everything will be under oil with the exception of the HV supply

My plan is to supply no more than 15 KV peak to the first CW stage since I have 30 KV capacitors. This should give me a theoretical output of 210 KV (15000 * 14). In order to protect the diodes I plan on having a HV resistor string attached to the final stage of the CW multiplier.

The current-limiting HV resistor string is what my question concerns. The most readily available, reasonably-priced, and compact resistor appears to be a Vishay VR68  with the following specs:

* Resistance: 470K ohms
* Voltage rating: 10 KV
* Power Rating: 1 watt

If I use 250 KV as the target resistor rating, this will require 25 resistors in series for a total resistance of 11.75M ohms. This should limit the current to more than 21 ma. I would actually like to use about half of this resistance value but the only way obvious to do that would be to place resistors in parallel which would double the number from 25 to 50 resistors. I would rather not do that for space reasons.

Does anyone have any suggestions concerning the HV resistor string?
Steve White
Cedar Rapids, Iowa
Retired electrical engineer

Offline plasma

  • High Voltage Enthusiast
  • *
  • Posts: 15
  • Karma: +0/-0
    • View Profile
Re: CW multiplier resistor string suggestions
« Reply #1 on: December 08, 2019, 12:00:00 AM »
1.7nF doorknob caps, will have a high discharge rate,
I had 10 1kv 1A diodes and 200nF at 50hz Z, the diodes should handle the current from the Mot, but when the sparkgap fired they all arc over, I added 30kohm ceramic and carbon film who h stopped it.
The CW boosted 2.4kv to 8kV, with two stages, the last stage had 5 1uF in series.
« Last Edit: December 08, 2019, 12:01:55 AM by plasma »

Offline davekni

  • High Voltage Technician
  • ***
  • Posts: 154
  • Karma: +5/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: CW multiplier resistor string suggestions
« Reply #2 on: December 08, 2019, 06:50:11 AM »
Steve,

The VR68 series goes down to 100K.  Arrow happens to have 150k in stock, VR68000001503JAC00.  Digikey has all the way down to 100k, but at a bit higher price.  Or, to you already have a set of 470k parts?
David Knierim

Offline MRMILSTAR

  • High Voltage Technician
  • ***
  • Posts: 140
  • Karma: +4/-0
  • Cedar Rapids, Iowa
    • View Profile
Re: CW multiplier resistor string suggestions
« Reply #3 on: December 08, 2019, 05:28:09 PM »
Steve,

The VR68 series goes down to 100K.  Arrow happens to have 150k in stock, VR68000001503JAC00.  Digikey has all the way down to 100k, but at a bit higher price.  Or, to you already have a set of 470k parts?

Thanks Dave! I tried using "oemstrade.com" that you suggested as the search tool. It does appear to be a very good parts search tool. I didn't know the exact part number I was searching for so I tried a generic "VR6800000". The only thing that came up as available in small quantities was the 470K part. When I entered the exact part number that you supplied a longer list of suppliers appeared. The moral of the story seems to be "know the exact part number".

I haven't bought any parts yet other than the capacitors which I already had because I got a great deal on them about a year ago. I generally don't buy any parts for projects until I have a complete design in hand otherwise I often end up wasting money because of mid-project design changes.
« Last Edit: December 08, 2019, 09:59:23 PM by MRMILSTAR »
Steve White
Cedar Rapids, Iowa
Retired electrical engineer

Offline davekni

  • High Voltage Technician
  • ***
  • Posts: 154
  • Karma: +5/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: CW multiplier resistor string suggestions
« Reply #4 on: December 08, 2019, 09:57:51 PM »
That's the value of searching on Digikey first, searching by parameter, then looking at oemstrade for better prices.  OEMs trade works reasonably well with partial part-number strings IF there are reasonably few matches.  Adding a single extra digit to your search makes it reasonable, "VR68000001".

BTW, the VR68 series has the value encoded in the four digits after the long string of 0's, three digits followed by a power-of-ten digit.  So, the VR68000001503JAC00 part is 150E3 or 150k.
David Knierim

High Voltage Forum

Re: CW multiplier resistor string suggestions
« Reply #4 on: December 08, 2019, 09:57:51 PM »

 


* Recent Topics and Posts

post Small DIY plasma globe using ZVS oscillator
[Transformer (Ferrite Core)]
davekni
Today at 06:21:31 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
Today at 05:54:17 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
Today at 05:45:43 AM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Twospoons
January 21, 2020, 10:54:44 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mads Barnkob
January 21, 2020, 08:05:20 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mysteriousduck
January 21, 2020, 03:49:24 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mads Barnkob
January 21, 2020, 08:37:14 AM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
klugesmith
January 20, 2020, 11:10:05 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
T3sl4co1l
January 20, 2020, 10:55:35 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
davekni
January 20, 2020, 09:48:06 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Twospoons
January 20, 2020, 08:31:54 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
SteveN87
January 20, 2020, 12:59:19 PM
post DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mads Barnkob
January 20, 2020, 11:13:23 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
HVZapp
January 20, 2020, 10:23:03 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
January 20, 2020, 05:55:07 AM
post Re: Why does this happen.
[General Chat]
thedoc298
January 19, 2020, 09:43:26 PM
post Re: Why does this happen.
[General Chat]
Mads Barnkob
January 19, 2020, 09:07:51 PM
post JavaTC question
[General Chat]
thedoc298
January 19, 2020, 09:01:06 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hydron
January 19, 2020, 01:08:17 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
January 19, 2020, 12:36:56 PM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
Mysteriousduck
January 19, 2020, 04:06:36 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
rvpilot
January 19, 2020, 02:00:30 AM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
T3sl4co1l
January 18, 2020, 08:51:26 PM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
klugesmith
January 18, 2020, 06:53:02 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mysteriousduck
January 18, 2020, 05:19:49 AM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
Mysteriousduck
January 18, 2020, 04:41:22 AM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
T3sl4co1l
January 18, 2020, 12:30:19 AM
post 500Khz Induction Heater - Need help with Driver
[Beginners]
Mysteriousduck
January 17, 2020, 11:17:33 PM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
klugesmith
January 17, 2020, 08:55:37 PM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
T3sl4co1l
January 17, 2020, 04:01:23 PM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
RobertL
January 17, 2020, 04:22:25 AM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
Twospoons
January 17, 2020, 01:37:37 AM
post Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
RobertL
January 16, 2020, 11:51:51 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Netzpfuscher
January 16, 2020, 11:59:04 AM
post Re: Easy Oscillator for Induction Heating and, Maybe Tesla Coil Power?
[Electronic Circuits]
T3sl4co1l
January 16, 2020, 02:53:32 AM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
acobaugh
January 15, 2020, 08:57:37 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
January 15, 2020, 07:27:10 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
acobaugh
January 15, 2020, 07:08:00 PM
post Re: Easy Oscillator for Induction Heating and, Maybe Tesla Coil Power?
[Electronic Circuits]
Mads Barnkob
January 15, 2020, 01:26:57 PM
post Re: Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
SteveN87
January 15, 2020, 12:37:28 PM
post Re: Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
Twospoons
January 15, 2020, 01:15:45 AM
post Easy Oscillator for Induction Heating and, Maybe Tesla Coil Power?
[Electronic Circuits]
petespaco
January 14, 2020, 11:19:23 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Nicko
January 14, 2020, 10:50:54 PM
post Ebay [US] 1x CM300HA-24H H-series, 20$ for a single switch brick
[Sell / Buy / Trade]
Mads Barnkob
January 14, 2020, 08:24:10 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
T3sl4co1l
January 14, 2020, 07:36:14 PM
post Re: Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
shrad
January 14, 2020, 12:51:32 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
davekni
January 14, 2020, 05:27:11 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
January 14, 2020, 02:27:54 AM
post Re: Ok now I'm stuck ¯\_(ツ)_/¯
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dj.cosmo.esq
January 13, 2020, 11:42:07 PM
post Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
Mads Barnkob
January 13, 2020, 11:30:11 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 
SimplePortal 2.3.6 © 2008-2014, SimplePortal