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Re: [VanDeGraaffGenerator] resistors value

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  • Bert Hickman
    Hi Doug, No problem - here s a PDF of the low pass filter circuit: http://www.capturedlightning.com/PDF/HV_Low_Pass_Filter.pdf Bert ... World s source for
    Message 1 of 15 , May 7, 2013
    • 0 Attachment
      Hi Doug,

      No problem - here's a PDF of the low pass filter circuit:
      http://www.capturedlightning.com/PDF/HV_Low_Pass_Filter.pdf

      Bert

      DOUG wrote:
      >
      >
      > Hi Bert; Sorry for my ignorance, but I don’t know how to do the
      > (fixed font) thing.
      >
      > Doug
      >
      > ------------------------------------------------------------------------
      >
      > *From:*VanDeGraaffGenerator@yahoogroups.com
      > [mailto:VanDeGraaffGenerator@yahoogroups.com] *On Behalf Of *Bert
      > Hickman *Sent:* Monday, May 06, 2013 12:42 PM *T**o:*
      > VanDeGraaffGenerator@yahoogroups.com *Subject:* Re:
      > [VanDeGraaffGenerator] resistors value
      >
      > Hi Doug,
      >
      > Sounds great! Marx generators are notorious for blowing up charging
      > supplies via back-fed transients through the HV lines and via ground
      > bounce :^)
      >
      > You can mitigate these problems by connecting a HV low-pass filter
      > between your HV source and the input of the Marx generator. I'd
      > recommend using the following RC circuit which will prevent both
      > types of transients from nuking your HV supply. Use a fixed font
      > (Courier) to display properly.
      >
      > R1 R1 <----/\/\/\/\----o-----/\/\/\/\------> | o--/\/\/\/\-- To | R2
      > | To HV ----- | Marx Supply ----- | input | | o------------ |
      > <----/\/\/\/\----o-----/\/\/\/\------> R1 R1
      >
      > The R1 resistor values are not critical, but they should all be
      > identical - anything above 100k will work. R2 is a bleeder, so it
      > should be in the 500 - 1000 Meg range to limit power dissipation.
      > Each resistor must be capable of handling transients at least as high
      > as your maximum supply voltage (25 kV in your case). The capacitor
      > can be a simple 30 - 40 kV ceramic doorknob cap in the 500 - 2000 pF
      > range.
      >
      > Be careful not to operate your Marx generator near any solid state
      > equipment, network wiring, computers, scopes, etc., since the EMP
      > can easily trash these devices.
      >
      > Good luck and play safely!
      >
      > Bert -- Bert Hickman Stoneridge Engineering
      > http://www.capturedlightning.com
      > ***********************************************************************
      >
      >
      World's source for "Captured Lightning" Lichtenberg Figure sculptures,
      > magnetically "shrunken" coins, and scarce/out of print technical
      > books
      > ***********************************************************************
      >
      > DOUG wrote:
      >>
      >>
      >> Thanks Bert; I do have a source for the VR68 1 watt 200K ohm
      >> resistors @.25 cents each so that sounds really good to me.
      >>
      >> Do you think I will need anything between my power supply and the
      >> first stage of the Marx?
      >>
      >> Doug
      >>
      >> ----------------------------------------------------------
      >>
      >> *From:*VanDeGraaffGenerator@yahoogroups.com
      > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
      >> [mailto:VanDeGraaffGenerator@yahoogroups.com
      > <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of *Bert
      >> Hickman *Sent:* Monday, May 06, 2013 1:21 AM *T**o:*
      >> VanDeGraaffGenerator@yahoogroups.com
      > <mailto:VanDeGraaffGenerator%40yahoogroups.com> *Subject:* Re:
      >> [VanDeGraaffGenerator] resistors value
      >>
      >> Hi Doug,
      >>
      >> A couple of alternatives would be VR68 or HVR68 1 watt HV metal
      >> film or ceramic resistors.These can handle 10 kV pulses, so you'll
      >> need to use at least two, and preferably three, resistors in series
      >> per stage. In your Marx application, the resistance value is not
      >> very critical since your stage capacitance is relatively small.To
      >> limit peak power stresses, use 100k - 200kohm resistors. You may
      >> also find something similar at a better price via eBay or through
      >> other electronic surplus vendors.
      >>
      >> Bert
      >>
      >> DOUG wrote:
      >>>
      >>>
      >>> Hi Bert;Thank you for your reply. I will be charging with a 25KV
      >>> power supply. Can you suggest something other than the 1 or 2
      >>> watt resisters?
      >>>
      >>> Douglas Johnson
      >>>
      >>> ----------------------------------------------------------
      >>>
      >>> *From:*VanDeGraaffGenerator@yahoogroups.com
      > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
      >> <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
      >>> [mailto:VanDeGraaffGenerator@yahoogroups.com
      > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
      >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of
      >> *Bert Hickman
      >>> *Sent:* Sunday, May 05, 2013 12:10 AM *T**o:*
      >>> VanDeGraaffGenerator@yahoogroups.com
      > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
      >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>
      >>> *Subject:* Re: [VanDeGraaffGenerator] resistors value
      >>>
      >>> HiDouglas,
      >>>
      >>> There is little difference in the voltage breakdown rating for
      >>> 1W and 2W carbon composite resistors. Your resistors must be able
      >>> to withstand the transient discharge voltage (i.e., the DC
      >>> charging voltage per resistor) when the Marx fires. If they flash
      >>> over, you'll dramatically decrease the output of your Marx
      >>> generator and any internal flashovers may cause the affected
      >>> resistor to explode or permanently change resistance value.
      >>>
      >>> For short (<10 uSec) pulse duty such as your Marx generator, a 1
      >>> or 2 watt carbon composition resistor can repetitively handle a
      >>> maximum of ~5-6 kV between terminals. So, if you plan to charge
      >>> your capacitors to 30 kV per stage, you'll need to use five-six
      >>> identical resistors in series (for each stage) to share the
      >>> voltage stress.
      >>>
      >>> Bert -- Bert Hickman Stoneridge Engineering
      >>> http://www.capturedlightning.com
      >>> ***********************************************************************
      >>>
      >>>
      >
      >>>
      World's source for "Captured Lightning" Lichtenberg Figure sculptures,
      >>> magnetically "shrunken" coins, and scarce/out of print
      >>> technical books
      >>> ***********************************************************************
      >>>
      >>>
      >>>
      >
      >>>
      drj11642 wrote:
      >>>> Here is my dilemma today, I need a bunch of 2 watt solid
      >>>> carbon resistors which are almost impossible to find, and when
      >>>> they can be found they are very expensive. On the other hand I
      >>>> have lots of 240ohms 1 watt solid carbon resistors. What would
      >>>> the resulting value be with 2 of these 1 watt resistors in
      >>>> series?
      >>>>
      >>>> My project that I need these for is a Marx generator using
      >>>> 30kv-1000pf ceramic disc caps.
      >>>>
      >>>> Thanks in advance to any response to my queries.
      >>>>
      >>>> Douglas Johnson
      >>>>
      >>>>
      >>>>
      >>>>
      >>>> ------------------------------------
      >>>>
      >>>> Yahoo! Groups Links
      >>>>
      >>>>
      >>>>
      >>>>
      >>>>
      >>>
      >>>
      >>>
      >>>
      >>
      >> -- Bert Hickman Stoneridge Engineering
      >> http://www.capturedlightning.com
      >> ***********************************************************************
      >>
      >>
      >
      >>
      World's source for "Captured Lightning" Lichtenberg Figure sculptures,
      >> magnetically "shrunken" coins, and scarce/out of print technical
      >> books
      >> ***********************************************************************
      >>
      >>
      >>
      >>
      >>
      >
      >>
      >
      >
      >
    • DOUG
      Thanks again Bert. Doug ... From: VanDeGraaffGenerator@yahoogroups.com [mailto:VanDeGraaffGenerator@yahoogroups.com] On Behalf Of Bert Hickman Sent: Tuesday,
      Message 2 of 15 , May 7, 2013
      • 0 Attachment
        Thanks again Bert.
        Doug

        -----Original Message-----
        From: VanDeGraaffGenerator@yahoogroups.com
        [mailto:VanDeGraaffGenerator@yahoogroups.com] On Behalf Of Bert Hickman
        Sent: Tuesday, May 07, 2013 12:03 PM
        To: VanDeGraaffGenerator@yahoogroups.com
        Subject: Re: [VanDeGraaffGenerator] resistors value

        Hi Doug,

        No problem - here's a PDF of the low pass filter circuit:
        http://www.capturedlightning.com/PDF/HV_Low_Pass_Filter.pdf

        Bert

        DOUG wrote:
        >
        >
        > Hi Bert; Sorry for my ignorance, but I don't know how to do the
        > (fixed font) thing.
        >
        > Doug
        >
        > ------------------------------------------------------------------------
        >
        > *From:*VanDeGraaffGenerator@yahoogroups.com
        > [mailto:VanDeGraaffGenerator@yahoogroups.com] *On Behalf Of *Bert
        > Hickman *Sent:* Monday, May 06, 2013 12:42 PM *T**o:*
        > VanDeGraaffGenerator@yahoogroups.com *Subject:* Re:
        > [VanDeGraaffGenerator] resistors value
        >
        > Hi Doug,
        >
        > Sounds great! Marx generators are notorious for blowing up charging
        > supplies via back-fed transients through the HV lines and via ground
        > bounce :^)
        >
        > You can mitigate these problems by connecting a HV low-pass filter
        > between your HV source and the input of the Marx generator. I'd
        > recommend using the following RC circuit which will prevent both
        > types of transients from nuking your HV supply. Use a fixed font
        > (Courier) to display properly.
        >
        > R1 R1 <----/\/\/\/\----o-----/\/\/\/\------> | o--/\/\/\/\-- To | R2
        > | To HV ----- | Marx Supply ----- | input | | o------------ |
        > <----/\/\/\/\----o-----/\/\/\/\------> R1 R1
        >
        > The R1 resistor values are not critical, but they should all be
        > identical - anything above 100k will work. R2 is a bleeder, so it
        > should be in the 500 - 1000 Meg range to limit power dissipation.
        > Each resistor must be capable of handling transients at least as high
        > as your maximum supply voltage (25 kV in your case). The capacitor
        > can be a simple 30 - 40 kV ceramic doorknob cap in the 500 - 2000 pF
        > range.
        >
        > Be careful not to operate your Marx generator near any solid state
        > equipment, network wiring, computers, scopes, etc., since the EMP
        > can easily trash these devices.
        >
        > Good luck and play safely!
        >
        > Bert -- Bert Hickman Stoneridge Engineering
        > http://www.capturedlightning.com
        > ***********************************************************************
        >
        >
        World's source for "Captured Lightning" Lichtenberg Figure sculptures,
        > magnetically "shrunken" coins, and scarce/out of print technical
        > books
        > ***********************************************************************
        >
        > DOUG wrote:
        >>
        >>
        >> Thanks Bert; I do have a source for the VR68 1 watt 200K ohm
        >> resistors @.25 cents each so that sounds really good to me.
        >>
        >> Do you think I will need anything between my power supply and the
        >> first stage of the Marx?
        >>
        >> Doug
        >>
        >> ----------------------------------------------------------
        >>
        >> *From:*VanDeGraaffGenerator@yahoogroups.com
        > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
        >> [mailto:VanDeGraaffGenerator@yahoogroups.com
        > <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of *Bert
        >> Hickman *Sent:* Monday, May 06, 2013 1:21 AM *T**o:*
        >> VanDeGraaffGenerator@yahoogroups.com
        > <mailto:VanDeGraaffGenerator%40yahoogroups.com> *Subject:* Re:
        >> [VanDeGraaffGenerator] resistors value
        >>
        >> Hi Doug,
        >>
        >> A couple of alternatives would be VR68 or HVR68 1 watt HV metal
        >> film or ceramic resistors.These can handle 10 kV pulses, so you'll
        >> need to use at least two, and preferably three, resistors in series
        >> per stage. In your Marx application, the resistance value is not
        >> very critical since your stage capacitance is relatively small.To
        >> limit peak power stresses, use 100k - 200kohm resistors. You may
        >> also find something similar at a better price via eBay or through
        >> other electronic surplus vendors.
        >>
        >> Bert
        >>
        >> DOUG wrote:
        >>>
        >>>
        >>> Hi Bert;Thank you for your reply. I will be charging with a 25KV
        >>> power supply. Can you suggest something other than the 1 or 2
        >>> watt resisters?
        >>>
        >>> Douglas Johnson
        >>>
        >>> ----------------------------------------------------------
        >>>
        >>> *From:*VanDeGraaffGenerator@yahoogroups.com
        > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
        >> <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
        >>> [mailto:VanDeGraaffGenerator@yahoogroups.com
        > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
        >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of
        >> *Bert Hickman
        >>> *Sent:* Sunday, May 05, 2013 12:10 AM *T**o:*
        >>> VanDeGraaffGenerator@yahoogroups.com
        > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
        >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>
        >>> *Subject:* Re: [VanDeGraaffGenerator] resistors value
        >>>
        >>> HiDouglas,
        >>>
        >>> There is little difference in the voltage breakdown rating for
        >>> 1W and 2W carbon composite resistors. Your resistors must be able
        >>> to withstand the transient discharge voltage (i.e., the DC
        >>> charging voltage per resistor) when the Marx fires. If they flash
        >>> over, you'll dramatically decrease the output of your Marx
        >>> generator and any internal flashovers may cause the affected
        >>> resistor to explode or permanently change resistance value.
        >>>
        >>> For short (<10 uSec) pulse duty such as your Marx generator, a 1
        >>> or 2 watt carbon composition resistor can repetitively handle a
        >>> maximum of ~5-6 kV between terminals. So, if you plan to charge
        >>> your capacitors to 30 kV per stage, you'll need to use five-six
        >>> identical resistors in series (for each stage) to share the
        >>> voltage stress.
        >>>
        >>> Bert -- Bert Hickman Stoneridge Engineering
        >>> http://www.capturedlightning.com
        >>> ***********************************************************************
        >>>
        >>>
        >
        >>>
        World's source for "Captured Lightning" Lichtenberg Figure sculptures,
        >>> magnetically "shrunken" coins, and scarce/out of print
        >>> technical books
        >>> ***********************************************************************
        >>>
        >>>
        >>>
        >
        >>>
        drj11642 wrote:
        >>>> Here is my dilemma today, I need a bunch of 2 watt solid
        >>>> carbon resistors which are almost impossible to find, and when
        >>>> they can be found they are very expensive. On the other hand I
        >>>> have lots of 240ohms 1 watt solid carbon resistors. What would
        >>>> the resulting value be with 2 of these 1 watt resistors in
        >>>> series?
        >>>>
        >>>> My project that I need these for is a Marx generator using
        >>>> 30kv-1000pf ceramic disc caps.
        >>>>
        >>>> Thanks in advance to any response to my queries.
        >>>>
        >>>> Douglas Johnson
        >>>>
        >>>>
        >>>>
        >>>>
        >>>> ------------------------------------
        >>>>
        >>>> Yahoo! Groups Links
        >>>>
        >>>>
        >>>>
        >>>>
        >>>>
        >>>
        >>>
        >>>
        >>>
        >>
        >> -- Bert Hickman Stoneridge Engineering
        >> http://www.capturedlightning.com
        >> ***********************************************************************
        >>
        >>
        >
        >>
        World's source for "Captured Lightning" Lichtenberg Figure sculptures,
        >> magnetically "shrunken" coins, and scarce/out of print technical
        >> books
        >> ***********************************************************************
        >>
        >>
        >>
        >>
        >>
        >
        >>
        >
        >
        >



        ------------------------------------

        Yahoo! Groups Links
      • DOUG
        Hi Again Bert; will 3 of the 1 watt 200 ohm VR68 s work for R2? ... From: VanDeGraaffGenerator@yahoogroups.com [mailto:VanDeGraaffGenerator@yahoogroups.com] On
        Message 3 of 15 , May 7, 2013
        • 0 Attachment
          Hi Again Bert; will 3 of the 1 watt 200 ohm VR68's work for R2?

          -----Original Message-----
          From: VanDeGraaffGenerator@yahoogroups.com
          [mailto:VanDeGraaffGenerator@yahoogroups.com] On Behalf Of Bert Hickman
          Sent: Tuesday, May 07, 2013 12:03 PM
          To: VanDeGraaffGenerator@yahoogroups.com
          Subject: Re: [VanDeGraaffGenerator] resistors value

          Hi Doug,

          No problem - here's a PDF of the low pass filter circuit:
          http://www.capturedlightning.com/PDF/HV_Low_Pass_Filter.pdf

          Bert

          DOUG wrote:
          >
          >
          > Hi Bert; Sorry for my ignorance, but I don't know how to do the
          > (fixed font) thing.
          >
          > Doug
          >
          > ------------------------------------------------------------------------
          >
          > *From:*VanDeGraaffGenerator@yahoogroups.com
          > [mailto:VanDeGraaffGenerator@yahoogroups.com] *On Behalf Of *Bert
          > Hickman *Sent:* Monday, May 06, 2013 12:42 PM *T**o:*
          > VanDeGraaffGenerator@yahoogroups.com *Subject:* Re:
          > [VanDeGraaffGenerator] resistors value
          >
          > Hi Doug,
          >
          > Sounds great! Marx generators are notorious for blowing up charging
          > supplies via back-fed transients through the HV lines and via ground
          > bounce :^)
          >
          > You can mitigate these problems by connecting a HV low-pass filter
          > between your HV source and the input of the Marx generator. I'd
          > recommend using the following RC circuit which will prevent both
          > types of transients from nuking your HV supply. Use a fixed font
          > (Courier) to display properly.
          >
          > R1 R1 <----/\/\/\/\----o-----/\/\/\/\------> | o--/\/\/\/\-- To | R2
          > | To HV ----- | Marx Supply ----- | input | | o------------ |
          > <----/\/\/\/\----o-----/\/\/\/\------> R1 R1
          >
          > The R1 resistor values are not critical, but they should all be
          > identical - anything above 100k will work. R2 is a bleeder, so it
          > should be in the 500 - 1000 Meg range to limit power dissipation.
          > Each resistor must be capable of handling transients at least as high
          > as your maximum supply voltage (25 kV in your case). The capacitor
          > can be a simple 30 - 40 kV ceramic doorknob cap in the 500 - 2000 pF
          > range.
          >
          > Be careful not to operate your Marx generator near any solid state
          > equipment, network wiring, computers, scopes, etc., since the EMP
          > can easily trash these devices.
          >
          > Good luck and play safely!
          >
          > Bert -- Bert Hickman Stoneridge Engineering
          > http://www.capturedlightning.com
          > ***********************************************************************
          >
          >
          World's source for "Captured Lightning" Lichtenberg Figure sculptures,
          > magnetically "shrunken" coins, and scarce/out of print technical
          > books
          > ***********************************************************************
          >
          > DOUG wrote:
          >>
          >>
          >> Thanks Bert; I do have a source for the VR68 1 watt 200K ohm
          >> resistors @.25 cents each so that sounds really good to me.
          >>
          >> Do you think I will need anything between my power supply and the
          >> first stage of the Marx?
          >>
          >> Doug
          >>
          >> ----------------------------------------------------------
          >>
          >> *From:*VanDeGraaffGenerator@yahoogroups.com
          > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
          >> [mailto:VanDeGraaffGenerator@yahoogroups.com
          > <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of *Bert
          >> Hickman *Sent:* Monday, May 06, 2013 1:21 AM *T**o:*
          >> VanDeGraaffGenerator@yahoogroups.com
          > <mailto:VanDeGraaffGenerator%40yahoogroups.com> *Subject:* Re:
          >> [VanDeGraaffGenerator] resistors value
          >>
          >> Hi Doug,
          >>
          >> A couple of alternatives would be VR68 or HVR68 1 watt HV metal
          >> film or ceramic resistors.These can handle 10 kV pulses, so you'll
          >> need to use at least two, and preferably three, resistors in series
          >> per stage. In your Marx application, the resistance value is not
          >> very critical since your stage capacitance is relatively small.To
          >> limit peak power stresses, use 100k - 200kohm resistors. You may
          >> also find something similar at a better price via eBay or through
          >> other electronic surplus vendors.
          >>
          >> Bert
          >>
          >> DOUG wrote:
          >>>
          >>>
          >>> Hi Bert;Thank you for your reply. I will be charging with a 25KV
          >>> power supply. Can you suggest something other than the 1 or 2
          >>> watt resisters?
          >>>
          >>> Douglas Johnson
          >>>
          >>> ----------------------------------------------------------
          >>>
          >>> *From:*VanDeGraaffGenerator@yahoogroups.com
          > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
          >> <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
          >>> [mailto:VanDeGraaffGenerator@yahoogroups.com
          > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
          >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of
          >> *Bert Hickman
          >>> *Sent:* Sunday, May 05, 2013 12:10 AM *T**o:*
          >>> VanDeGraaffGenerator@yahoogroups.com
          > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
          >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>
          >>> *Subject:* Re: [VanDeGraaffGenerator] resistors value
          >>>
          >>> HiDouglas,
          >>>
          >>> There is little difference in the voltage breakdown rating for
          >>> 1W and 2W carbon composite resistors. Your resistors must be able
          >>> to withstand the transient discharge voltage (i.e., the DC
          >>> charging voltage per resistor) when the Marx fires. If they flash
          >>> over, you'll dramatically decrease the output of your Marx
          >>> generator and any internal flashovers may cause the affected
          >>> resistor to explode or permanently change resistance value.
          >>>
          >>> For short (<10 uSec) pulse duty such as your Marx generator, a 1
          >>> or 2 watt carbon composition resistor can repetitively handle a
          >>> maximum of ~5-6 kV between terminals. So, if you plan to charge
          >>> your capacitors to 30 kV per stage, you'll need to use five-six
          >>> identical resistors in series (for each stage) to share the
          >>> voltage stress.
          >>>
          >>> Bert -- Bert Hickman Stoneridge Engineering
          >>> http://www.capturedlightning.com
          >>> ***********************************************************************
          >>>
          >>>
          >
          >>>
          World's source for "Captured Lightning" Lichtenberg Figure sculptures,
          >>> magnetically "shrunken" coins, and scarce/out of print
          >>> technical books
          >>> ***********************************************************************
          >>>
          >>>
          >>>
          >
          >>>
          drj11642 wrote:
          >>>> Here is my dilemma today, I need a bunch of 2 watt solid
          >>>> carbon resistors which are almost impossible to find, and when
          >>>> they can be found they are very expensive. On the other hand I
          >>>> have lots of 240ohms 1 watt solid carbon resistors. What would
          >>>> the resulting value be with 2 of these 1 watt resistors in
          >>>> series?
          >>>>
          >>>> My project that I need these for is a Marx generator using
          >>>> 30kv-1000pf ceramic disc caps.
          >>>>
          >>>> Thanks in advance to any response to my queries.
          >>>>
          >>>> Douglas Johnson
          >>>>
          >>>>
          >>>>
          >>>>
          >>>> ------------------------------------
          >>>>
          >>>> Yahoo! Groups Links
          >>>>
          >>>>
          >>>>
          >>>>
          >>>>
          >>>
          >>>
          >>>
          >>>
          >>
          >> -- Bert Hickman Stoneridge Engineering
          >> http://www.capturedlightning.com
          >> ***********************************************************************
          >>
          >>
          >
          >>
          World's source for "Captured Lightning" Lichtenberg Figure sculptures,
          >> magnetically "shrunken" coins, and scarce/out of print technical
          >> books
          >> ***********************************************************************
          >>
          >>
          >>
          >>
          >>
          >
          >>
          >
          >
          >



          ------------------------------------

          Yahoo! Groups Links
        • Bert Hickman
          Hi Doug, Yes. Bert ... *From:*VanDeGraaffGenerator@yahoogroups.com ... World s source for Captured Lightning Lichtenberg Figure sculptures, ... World s
          Message 4 of 15 , May 7, 2013
          • 0 Attachment
            Hi Doug,

            Yes.

            Bert

            DOUG wrote:
            > Hi Again Bert; will 3 of the 1 watt 200 ohm VR68's work for R2?
            >
            > -----Original Message----- From:
            > VanDeGraaffGenerator@yahoogroups.com
            > [mailto:VanDeGraaffGenerator@yahoogroups.com] On Behalf Of Bert
            > Hickman Sent: Tuesday, May 07, 2013 12:03 PM To:
            > VanDeGraaffGenerator@yahoogroups.com Subject: Re:
            > [VanDeGraaffGenerator] resistors value
            >
            > Hi Doug,
            >
            > No problem - here's a PDF of the low pass filter circuit:
            > http://www.capturedlightning.com/PDF/HV_Low_Pass_Filter.pdf
            >
            > Bert
            >
            > DOUG wrote:
            >>
            >>
            >> Hi Bert; Sorry for my ignorance, but I don't know how to do the
            >> (fixed font) thing.
            >>
            >> Doug
            >>
            >> ------------------------------------------------------------------------
            >>
            >>
            >>
            *From:*VanDeGraaffGenerator@yahoogroups.com
            >> [mailto:VanDeGraaffGenerator@yahoogroups.com] *On Behalf Of *Bert
            >> Hickman *Sent:* Monday, May 06, 2013 12:42 PM *T**o:*
            >> VanDeGraaffGenerator@yahoogroups.com *Subject:* Re:
            >> [VanDeGraaffGenerator] resistors value
            >>
            >> Hi Doug,
            >>
            >> Sounds great! Marx generators are notorious for blowing up
            >> charging supplies via back-fed transients through the HV lines and
            >> via ground bounce :^)
            >>
            >> You can mitigate these problems by connecting a HV low-pass filter
            >> between your HV source and the input of the Marx generator. I'd
            >> recommend using the following RC circuit which will prevent both
            >> types of transients from nuking your HV supply. Use a fixed font
            >> (Courier) to display properly.
            >>
            >> R1 R1 <----/\/\/\/\----o-----/\/\/\/\------> | o--/\/\/\/\-- To |
            >> R2 | To HV ----- | Marx Supply ----- | input | | o------------ |
            >> <----/\/\/\/\----o-----/\/\/\/\------> R1 R1
            >>
            >> The R1 resistor values are not critical, but they should all be
            >> identical - anything above 100k will work. R2 is a bleeder, so it
            >> should be in the 500 - 1000 Meg range to limit power dissipation.
            >> Each resistor must be capable of handling transients at least as
            >> high as your maximum supply voltage (25 kV in your case). The
            >> capacitor can be a simple 30 - 40 kV ceramic doorknob cap in the
            >> 500 - 2000 pF range.
            >>
            >> Be careful not to operate your Marx generator near any solid state
            >> equipment, network wiring, computers, scopes, etc., since the EMP
            >> can easily trash these devices.
            >>
            >> Good luck and play safely!
            >>
            >> Bert -- Bert Hickman Stoneridge Engineering
            >> http://www.capturedlightning.com
            >> ***********************************************************************
            >>
            >>
            >
            >>
            World's source for "Captured Lightning" Lichtenberg Figure sculptures,
            >> magnetically "shrunken" coins, and scarce/out of print technical
            >> books
            >> ***********************************************************************
            >>
            >>
            >>
            DOUG wrote:
            >>>
            >>>
            >>> Thanks Bert; I do have a source for the VR68 1 watt 200K ohm
            >>> resistors @.25 cents each so that sounds really good to me.
            >>>
            >>> Do you think I will need anything between my power supply and
            >>> the first stage of the Marx?
            >>>
            >>> Doug
            >>>
            >>> ----------------------------------------------------------
            >>>
            >>> *From:*VanDeGraaffGenerator@yahoogroups.com
            >> <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
            >>> [mailto:VanDeGraaffGenerator@yahoogroups.com
            >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of
            >> *Bert
            >>> Hickman *Sent:* Monday, May 06, 2013 1:21 AM *T**o:*
            >>> VanDeGraaffGenerator@yahoogroups.com
            >> <mailto:VanDeGraaffGenerator%40yahoogroups.com> *Subject:* Re:
            >>> [VanDeGraaffGenerator] resistors value
            >>>
            >>> Hi Doug,
            >>>
            >>> A couple of alternatives would be VR68 or HVR68 1 watt HV metal
            >>> film or ceramic resistors.These can handle 10 kV pulses, so
            >>> you'll need to use at least two, and preferably three, resistors
            >>> in series per stage. In your Marx application, the resistance
            >>> value is not very critical since your stage capacitance is
            >>> relatively small.To limit peak power stresses, use 100k - 200kohm
            >>> resistors. You may also find something similar at a better price
            >>> via eBay or through other electronic surplus vendors.
            >>>
            >>> Bert
            >>>
            >>> DOUG wrote:
            >>>>
            >>>>
            >>>> Hi Bert;Thank you for your reply. I will be charging with a
            >>>> 25KV power supply. Can you suggest something other than the 1
            >>>> or 2 watt resisters?
            >>>>
            >>>> Douglas Johnson
            >>>>
            >>>> ----------------------------------------------------------
            >>>>
            >>>> *From:*VanDeGraaffGenerator@yahoogroups.com
            >> <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
            >>> <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
            >>>> [mailto:VanDeGraaffGenerator@yahoogroups.com
            >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>
            >>> <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of
            >>> *Bert Hickman
            >>>> *Sent:* Sunday, May 05, 2013 12:10 AM *T**o:*
            >>>> VanDeGraaffGenerator@yahoogroups.com
            >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>
            >>> <mailto:VanDeGraaffGenerator%40yahoogroups.com>
            >>>> *Subject:* Re: [VanDeGraaffGenerator] resistors value
            >>>>
            >>>> HiDouglas,
            >>>>
            >>>> There is little difference in the voltage breakdown rating for
            >>>> 1W and 2W carbon composite resistors. Your resistors must be
            >>>> able to withstand the transient discharge voltage (i.e., the
            >>>> DC charging voltage per resistor) when the Marx fires. If they
            >>>> flash over, you'll dramatically decrease the output of your
            >>>> Marx generator and any internal flashovers may cause the
            >>>> affected resistor to explode or permanently change resistance
            >>>> value.
            >>>>
            >>>> For short (<10 uSec) pulse duty such as your Marx generator, a
            >>>> 1 or 2 watt carbon composition resistor can repetitively handle
            >>>> a maximum of ~5-6 kV between terminals. So, if you plan to
            >>>> charge your capacitors to 30 kV per stage, you'll need to use
            >>>> five-six identical resistors in series (for each stage) to
            >>>> share the voltage stress.
            >>>>
            >>>> Bert -- Bert Hickman Stoneridge Engineering
            >>>> http://www.capturedlightning.com
            >>>> ***********************************************************************
            >>>>
            >>>>
            >>
            >>>>
            >
            >>>>
            World's source for "Captured Lightning" Lichtenberg Figure sculptures,
            >>>> magnetically "shrunken" coins, and scarce/out of print
            >>>> technical books
            >>>> ***********************************************************************
            >>>>
            >>>>
            >>>>
            >>
            >>>>
            >
            >>>>
            drj11642 wrote:
            >>>>> Here is my dilemma today, I need a bunch of 2 watt solid
            >>>>> carbon resistors which are almost impossible to find, and
            >>>>> when they can be found they are very expensive. On the other
            >>>>> hand I have lots of 240ohms 1 watt solid carbon resistors.
            >>>>> What would the resulting value be with 2 of these 1 watt
            >>>>> resistors in series?
            >>>>>
            >>>>> My project that I need these for is a Marx generator using
            >>>>> 30kv-1000pf ceramic disc caps.
            >>>>>
            >>>>> Thanks in advance to any response to my queries.
            >>>>>
            >>>>> Douglas Johnson
            >>>>>
            >>>>>
            >>>>>
            >>>>>
            >>>>> ------------------------------------
            >>>>>
            >>>>> Yahoo! Groups Links
            >>>>>
            >>>>>
            >>>>>
            >>>>>
            >>>>>
            >>>>
            >>>>
            >>>>
            >>>>
            >>>
            >>> -- Bert Hickman Stoneridge Engineering
            >>> http://www.capturedlightning.com
            >>> ***********************************************************************
            >>>
            >>>
            >>
            >>>
            >
            >>>
            World's source for "Captured Lightning" Lichtenberg Figure sculptures,
            >>> magnetically "shrunken" coins, and scarce/out of print technical
            >>> books
            >>> ***********************************************************************
            >>>
            >>>
            >>>
            >>>
            >>>
            >>
            >>>
            >>
            >>
            >>
            >
            >>>
            >
            >
            > ------------------------------------
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
            > ------------------------------------
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
          • DOUG
            Hi Bert; Thank you again and thanks also to all the other members who responded to my questions regarding the build of a Marx Generator. All components are
            Message 5 of 15 , May 9, 2013
            • 0 Attachment
              Hi Bert; Thank you again and thanks also to all the other members who
              responded to my questions regarding the build of a Marx Generator.
              All components are ordered and on their way, so I will soon be soldering
              away!
              It is great to find people such as yourselves that can find time to respond
              to a, non-technical, person with a hobby quite over his head. LOL
              Thanks again to all;
              Douglas Johnson

              -----Original Message-----
              From: VanDeGraaffGenerator@yahoogroups.com
              [mailto:VanDeGraaffGenerator@yahoogroups.com] On Behalf Of Bert Hickman
              Sent: Tuesday, May 07, 2013 12:03 PM
              To: VanDeGraaffGenerator@yahoogroups.com
              Subject: Re: [VanDeGraaffGenerator] resistors value

              Hi Doug,

              No problem - here's a PDF of the low pass filter circuit:
              http://www.capturedlightning.com/PDF/HV_Low_Pass_Filter.pdf

              Bert

              DOUG wrote:
              >
              >
              > Hi Bert; Sorry for my ignorance, but I don't know how to do the
              > (fixed font) thing.
              >
              > Doug
              >
              > ------------------------------------------------------------------------
              >
              > *From:*VanDeGraaffGenerator@yahoogroups.com
              > [mailto:VanDeGraaffGenerator@yahoogroups.com] *On Behalf Of *Bert
              > Hickman *Sent:* Monday, May 06, 2013 12:42 PM *T**o:*
              > VanDeGraaffGenerator@yahoogroups.com *Subject:* Re:
              > [VanDeGraaffGenerator] resistors value
              >
              > Hi Doug,
              >
              > Sounds great! Marx generators are notorious for blowing up charging
              > supplies via back-fed transients through the HV lines and via ground
              > bounce :^)
              >
              > You can mitigate these problems by connecting a HV low-pass filter
              > between your HV source and the input of the Marx generator. I'd
              > recommend using the following RC circuit which will prevent both
              > types of transients from nuking your HV supply. Use a fixed font
              > (Courier) to display properly.
              >
              > R1 R1 <----/\/\/\/\----o-----/\/\/\/\------> | o--/\/\/\/\-- To | R2
              > | To HV ----- | Marx Supply ----- | input | | o------------ |
              > <----/\/\/\/\----o-----/\/\/\/\------> R1 R1
              >
              > The R1 resistor values are not critical, but they should all be
              > identical - anything above 100k will work. R2 is a bleeder, so it
              > should be in the 500 - 1000 Meg range to limit power dissipation.
              > Each resistor must be capable of handling transients at least as high
              > as your maximum supply voltage (25 kV in your case). The capacitor
              > can be a simple 30 - 40 kV ceramic doorknob cap in the 500 - 2000 pF
              > range.
              >
              > Be careful not to operate your Marx generator near any solid state
              > equipment, network wiring, computers, scopes, etc., since the EMP
              > can easily trash these devices.
              >
              > Good luck and play safely!
              >
              > Bert -- Bert Hickman Stoneridge Engineering
              > http://www.capturedlightning.com
              > ***********************************************************************
              >
              >
              World's source for "Captured Lightning" Lichtenberg Figure sculptures,
              > magnetically "shrunken" coins, and scarce/out of print technical
              > books
              > ***********************************************************************
              >
              > DOUG wrote:
              >>
              >>
              >> Thanks Bert; I do have a source for the VR68 1 watt 200K ohm
              >> resistors @.25 cents each so that sounds really good to me.
              >>
              >> Do you think I will need anything between my power supply and the
              >> first stage of the Marx?
              >>
              >> Doug
              >>
              >> ----------------------------------------------------------
              >>
              >> *From:*VanDeGraaffGenerator@yahoogroups.com
              > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
              >> [mailto:VanDeGraaffGenerator@yahoogroups.com
              > <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of *Bert
              >> Hickman *Sent:* Monday, May 06, 2013 1:21 AM *T**o:*
              >> VanDeGraaffGenerator@yahoogroups.com
              > <mailto:VanDeGraaffGenerator%40yahoogroups.com> *Subject:* Re:
              >> [VanDeGraaffGenerator] resistors value
              >>
              >> Hi Doug,
              >>
              >> A couple of alternatives would be VR68 or HVR68 1 watt HV metal
              >> film or ceramic resistors.These can handle 10 kV pulses, so you'll
              >> need to use at least two, and preferably three, resistors in series
              >> per stage. In your Marx application, the resistance value is not
              >> very critical since your stage capacitance is relatively small.To
              >> limit peak power stresses, use 100k - 200kohm resistors. You may
              >> also find something similar at a better price via eBay or through
              >> other electronic surplus vendors.
              >>
              >> Bert
              >>
              >> DOUG wrote:
              >>>
              >>>
              >>> Hi Bert;Thank you for your reply. I will be charging with a 25KV
              >>> power supply. Can you suggest something other than the 1 or 2
              >>> watt resisters?
              >>>
              >>> Douglas Johnson
              >>>
              >>> ----------------------------------------------------------
              >>>
              >>> *From:*VanDeGraaffGenerator@yahoogroups.com
              > <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
              >> <mailto:%2AVanDeGraaffGenerator%40yahoogroups.com>
              >>> [mailto:VanDeGraaffGenerator@yahoogroups.com
              > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
              >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>] *On Behalf Of
              >> *Bert Hickman
              >>> *Sent:* Sunday, May 05, 2013 12:10 AM *T**o:*
              >>> VanDeGraaffGenerator@yahoogroups.com
              > <mailto:VanDeGraaffGenerator%40yahoogroups.com>
              >> <mailto:VanDeGraaffGenerator%40yahoogroups.com>
              >>> *Subject:* Re: [VanDeGraaffGenerator] resistors value
              >>>
              >>> HiDouglas,
              >>>
              >>> There is little difference in the voltage breakdown rating for
              >>> 1W and 2W carbon composite resistors. Your resistors must be able
              >>> to withstand the transient discharge voltage (i.e., the DC
              >>> charging voltage per resistor) when the Marx fires. If they flash
              >>> over, you'll dramatically decrease the output of your Marx
              >>> generator and any internal flashovers may cause the affected
              >>> resistor to explode or permanently change resistance value.
              >>>
              >>> For short (<10 uSec) pulse duty such as your Marx generator, a 1
              >>> or 2 watt carbon composition resistor can repetitively handle a
              >>> maximum of ~5-6 kV between terminals. So, if you plan to charge
              >>> your capacitors to 30 kV per stage, you'll need to use five-six
              >>> identical resistors in series (for each stage) to share the
              >>> voltage stress.
              >>>
              >>> Bert -- Bert Hickman Stoneridge Engineering
              >>> http://www.capturedlightning.com
              >>> ***********************************************************************
              >>>
              >>>
              >
              >>>
              World's source for "Captured Lightning" Lichtenberg Figure sculptures,
              >>> magnetically "shrunken" coins, and scarce/out of print
              >>> technical books
              >>> ***********************************************************************
              >>>
              >>>
              >>>
              >
              >>>
              drj11642 wrote:
              >>>> Here is my dilemma today, I need a bunch of 2 watt solid
              >>>> carbon resistors which are almost impossible to find, and when
              >>>> they can be found they are very expensive. On the other hand I
              >>>> have lots of 240ohms 1 watt solid carbon resistors. What would
              >>>> the resulting value be with 2 of these 1 watt resistors in
              >>>> series?
              >>>>
              >>>> My project that I need these for is a Marx generator using
              >>>> 30kv-1000pf ceramic disc caps.
              >>>>
              >>>> Thanks in advance to any response to my queries.
              >>>>
              >>>> Douglas Johnson
              >>>>
              >>>>
              >>>>
              >>>>
              >>>> ------------------------------------
              >>>>
              >>>> Yahoo! Groups Links
              >>>>
              >>>>
              >>>>
              >>>>
              >>>>
              >>>
              >>>
              >>>
              >>>
              >>
              >> -- Bert Hickman Stoneridge Engineering
              >> http://www.capturedlightning.com
              >> ***********************************************************************
              >>
              >>
              >
              >>
              World's source for "Captured Lightning" Lichtenberg Figure sculptures,
              >> magnetically "shrunken" coins, and scarce/out of print technical
              >> books
              >> ***********************************************************************
              >>
              >>
              >>
              >>
              >>
              >
              >>
              >
              >
              >



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