Wow, This VARIAN Multiplier is really cool !!
sparky99, Wed Mar 20 2013, 09:47PMPicked this up off ePay, mislabeled as a High Voltage Rectifier. Looks like a Cockcroft Walton multiplier. About 22" high and a foot in diameter, 20 lb. Not much online about this unit, just a business called NxSemi, that lists it (H1260001), but it shows out of stock. Caps in this thing are about 3" long x 1" diameter, rated at 30 KVDC, there are 34 of 'em. There is what looks like a driver transformer on the bottom, and it's fairly small. Looks like I have a bit of reverse engineering to do on this one. This also has a pair of (Actually 34 pairs) 220K carbon comp 2W resistors between stages. Also has 34 diodes and 9 unidentified components. All the components are sleeved in teflon. Based on the size of the driving transformer, I don't think it's running at 60 Hz.
I've worked with TC's and LARGE Jacobs Ladders, but never with multipliers (except when I did color TV repair) and nothing this big. Any ideas, thoughts or comments on this are very welcome.
Best Regards,
Sparky 99
Re: Wow, This VARIAN Multiplier is really cool !!
Noah Hoppis, Wed Mar 20 2013, 11:07PM
WOW! how much did you get that one for? I bet that thing was for serious voltage or RF if it has all of those corona rings! That thing was designed for serious over-volting. did it say anything about what is was for?
Noah Hoppis, Wed Mar 20 2013, 11:07PM
WOW! how much did you get that one for? I bet that thing was for serious voltage or RF if it has all of those corona rings! That thing was designed for serious over-volting. did it say anything about what is was for?
Re: Wow, This VARIAN Multiplier is really cool !!
sparky99, Wed Mar 20 2013, 11:14PM
It was less than $200, including shipping from CA to NY. I'll bet it cost WAY more than that, new. He said it was used for testing, but beyond that, he didn't have a clue.
Sparky 99
sparky99, Wed Mar 20 2013, 11:14PM
It was less than $200, including shipping from CA to NY. I'll bet it cost WAY more than that, new. He said it was used for testing, but beyond that, he didn't have a clue.
Sparky 99
Re: Wow, This VARIAN Multiplier is really cool !!
Proud Mary, Wed Mar 20 2013, 11:31PM
It's the voltage multiplier module from a Wallis HV Adjustable E-Beam PSU.
The outfit comprises a mains-powered (120V 60Hz) driver unit and your 8-stage VM stack. The driver comes in a standard rack mount chassis. Driver panel meters are 0 - 200 kV and 0 - 5 mA.
I believe the driver rack-mount unit is the assembly made by Varian, and the stack by Wallis.
Proud Mary, Wed Mar 20 2013, 11:31PM
It's the voltage multiplier module from a Wallis HV Adjustable E-Beam PSU.
The outfit comprises a mains-powered (120V 60Hz) driver unit and your 8-stage VM stack. The driver comes in a standard rack mount chassis. Driver panel meters are 0 - 200 kV and 0 - 5 mA.
I believe the driver rack-mount unit is the assembly made by Varian, and the stack by Wallis.
Re: Wow, This VARIAN Multiplier is really cool !!
Steve Conner, Thu Mar 21 2013, 10:06AM
I don't think the little black box is the driver transformer. It's way too small for the input voltage implied by the output voltage and number of stages.
The two large white terminals on the bottom look like the AC inputs, from a separate driver transformer that would have mounted underneath the stack.
Steve Conner, Thu Mar 21 2013, 10:06AM
I don't think the little black box is the driver transformer. It's way too small for the input voltage implied by the output voltage and number of stages.
The two large white terminals on the bottom look like the AC inputs, from a separate driver transformer that would have mounted underneath the stack.
Re: Wow, This VARIAN Multiplier is really cool !!
Proud Mary, Thu Mar 21 2013, 11:04AM
Here is the driver unit for Sparky's Wallis VM stack.
Proud Mary, Thu Mar 21 2013, 11:04AM
Here is the driver unit for Sparky's Wallis VM stack.
Re: Wow, This VARIAN Multiplier is really cool !!
sparky99, Thu Mar 21 2013, 02:31PM
Well, I finally got the cover off what I thought might be an awfully small driver xfmr, only to find a circuit board with 4 NE-2 neon bulbs, 3 resistors one cap and a pair of zener diodes. There are 3 shielded cables and a seperate ground that go to the driver unit. Maybe two for measuring E and I, and one powering the stack. These shielded cables are small (Like the size of RG-174 coax), so I'm thinking the driving voltage can't be really high. I don't see any connection points on the inside of the feed through delrin insulators, except maybe the corona ball pictured. I guess that could be a feed point, as there is one on each side of the stack. Each side of the stack has 2 rows of caps, one row has 8 caps, the other nine caps. Same thing on the other side. From the corona ball, there is a pair of 220K resistors in series that feeds one row of caps, the other row is fed through a diode. third connection off the corona ball feeds the PC board through a diode. Ditto for the other side of the stack.
Anybody know the drive voltage / frequency for the stack?
After looking at this again, I think that Steve is correct. These RG-174 sized cables can't be the input. Later I'm going to spend some time reverse engineering the stack and that should answer some questions. Keep those ideas coming, It' starting to make some sense.
Best Regards,
Sparky 99
sparky99, Thu Mar 21 2013, 02:31PM
Well, I finally got the cover off what I thought might be an awfully small driver xfmr, only to find a circuit board with 4 NE-2 neon bulbs, 3 resistors one cap and a pair of zener diodes. There are 3 shielded cables and a seperate ground that go to the driver unit. Maybe two for measuring E and I, and one powering the stack. These shielded cables are small (Like the size of RG-174 coax), so I'm thinking the driving voltage can't be really high. I don't see any connection points on the inside of the feed through delrin insulators, except maybe the corona ball pictured. I guess that could be a feed point, as there is one on each side of the stack. Each side of the stack has 2 rows of caps, one row has 8 caps, the other nine caps. Same thing on the other side. From the corona ball, there is a pair of 220K resistors in series that feeds one row of caps, the other row is fed through a diode. third connection off the corona ball feeds the PC board through a diode. Ditto for the other side of the stack.
Anybody know the drive voltage / frequency for the stack?
After looking at this again, I think that Steve is correct. These RG-174 sized cables can't be the input. Later I'm going to spend some time reverse engineering the stack and that should answer some questions. Keep those ideas coming, It' starting to make some sense.
Best Regards,
Sparky 99
Re: Wow, This VARIAN Multiplier is really cool !!
HV Enthusiast, Thu Mar 21 2013, 02:33PM
I would contact Varian directly and ask them to send you some documentation.
HV Enthusiast, Thu Mar 21 2013, 02:33PM
I would contact Varian directly and ask them to send you some documentation.
Re: Wow, This VARIAN Multiplier is really cool !!
Proud Mary, Thu Mar 21 2013, 03:11PM
Wallis was a specialist company located in Worthing on the south coast of England. In 1992, the trademark "Wallis HiVolt" was acquired by Farnell.
Proud Mary, Thu Mar 21 2013, 03:11PM
Wallis was a specialist company located in Worthing on the south coast of England. In 1992, the trademark "Wallis HiVolt" was acquired by Farnell.
Re: Wow, This VARIAN Multiplier is really cool !!
teravolt, Thu Mar 21 2013, 04:18PM
good find, it has 17 stages at 30kv max so I think it is for 500Kv so you will need oil or sf6 to run it. You can make a power supply out of a ZVS
teravolt, Thu Mar 21 2013, 04:18PM
good find, it has 17 stages at 30kv max so I think it is for 500Kv so you will need oil or sf6 to run it. You can make a power supply out of a ZVS
Re: Wow, This VARIAN Multiplier is really cool !!
Ash Small, Thu Mar 21 2013, 04:41PM
I'm guessing here, but when I was reverse engineering one, I was advised by members here that, although the capacitor ratings would imply it was capable of 100kV, there was probably a safety margin of x2, so it was probably designed for 50kV, which, by the same logic, would imply that this one was designed for ~250kV.
Are the two sides separate, ie does one side multiply the positive, and the other the negative, to give an output of (say) +125kV, and -125kV, or is it one continuous multiplier giving either + or - 250kV?
Edit: I've just re-read PM's post above, and she quotes '200kV' output max.
Ash Small, Thu Mar 21 2013, 04:41PM
teravolt wrote ...
good find, it has 17 stages at 30kv max so I think it is for 500Kv so you will need oil or sf6 to run it. You can make a power supply out of a ZVS
good find, it has 17 stages at 30kv max so I think it is for 500Kv so you will need oil or sf6 to run it. You can make a power supply out of a ZVS
I'm guessing here, but when I was reverse engineering one, I was advised by members here that, although the capacitor ratings would imply it was capable of 100kV, there was probably a safety margin of x2, so it was probably designed for 50kV, which, by the same logic, would imply that this one was designed for ~250kV.
Are the two sides separate, ie does one side multiply the positive, and the other the negative, to give an output of (say) +125kV, and -125kV, or is it one continuous multiplier giving either + or - 250kV?
Edit: I've just re-read PM's post above, and she quotes '200kV' output max.
Re: Wow, This VARIAN Multiplier is really cool !!
Proud Mary, Thu Mar 21 2013, 05:58PM
The complete apparatus - the driver plus Wallis VM stack - is specified as 180 kV + 5 mA. As I said above, the two meters on the Varian driver unit are calibrated to 200 kV and 5 mA FSD using data fed back from the stack.
Incidentally there are not 17 stages in the stack, but 8.5.
8 kV RMS input will produce an output bracketing 180 kV depending on load and frequency. I would guess that the driver unit increased its output voltage and frequency to compensate for C&W 'sag' under increasing load. For experimental purposes, 8 kV RMS 30 - 50 kHz at up to 100 mA would be a good place to start.
The 30 kV Suflex capacitor rating - 30 kV - is roughly 2.5 times the peak voltage corresponding to 8 kV RMS, as we would expect to see in reliably engineered equipment.
Proud Mary, Thu Mar 21 2013, 05:58PM
The complete apparatus - the driver plus Wallis VM stack - is specified as 180 kV + 5 mA. As I said above, the two meters on the Varian driver unit are calibrated to 200 kV and 5 mA FSD using data fed back from the stack.
Incidentally there are not 17 stages in the stack, but 8.5.
8 kV RMS input will produce an output bracketing 180 kV depending on load and frequency. I would guess that the driver unit increased its output voltage and frequency to compensate for C&W 'sag' under increasing load. For experimental purposes, 8 kV RMS 30 - 50 kHz at up to 100 mA would be a good place to start.
The 30 kV Suflex capacitor rating - 30 kV - is roughly 2.5 times the peak voltage corresponding to 8 kV RMS, as we would expect to see in reliably engineered equipment.
Re: Wow, This VARIAN Multiplier is really cool !!
paris, Fri Mar 22 2013, 08:30AM
what size caps are those and where would someone find equivalents?
I had a search only found 30kv ceramic
that thing looks great
paris, Fri Mar 22 2013, 08:30AM
what size caps are those and where would someone find equivalents?
I had a search only found 30kv ceramic
that thing looks great
Re: Wow, This VARIAN Multiplier is really cool !!
Steve Conner, Fri Mar 22 2013, 10:49AM
I've seen Russian capacitors of similar ratings on Ebay. Mike Harrison used them for his Marx generator.
The unit is probably designed for use in air. The big corona rings wouldn't be needed under oil. Also there are no oil seals on any of the cables.
For fun, you could try powering it up with 60Hz from a NST. Since it has two AC inputs, it's probably a full-wave stack, which suggests you should connect one end of the NST to each input and the centre tap to the stack's ground terminal (probably the metal base plate?)
The output current would be greatly reduced, but you could still do some fun electrostatic experiments. I can recommend the packing peanut fountain.
Be careful when pulling arcs, as not all C-W multipliers are rated to survive this. The diodes may fail after a few good zaps. If there really are carbon comp resistors between the stages, that is a good sign, they're probably there to protect it from arcs.
Proud Mary, do you have one of these?
Steve Conner, Fri Mar 22 2013, 10:49AM
I've seen Russian capacitors of similar ratings on Ebay. Mike Harrison used them for his Marx generator.
The unit is probably designed for use in air. The big corona rings wouldn't be needed under oil. Also there are no oil seals on any of the cables.
For fun, you could try powering it up with 60Hz from a NST. Since it has two AC inputs, it's probably a full-wave stack, which suggests you should connect one end of the NST to each input and the centre tap to the stack's ground terminal (probably the metal base plate?)
The output current would be greatly reduced, but you could still do some fun electrostatic experiments. I can recommend the packing peanut fountain.
Be careful when pulling arcs, as not all C-W multipliers are rated to survive this. The diodes may fail after a few good zaps. If there really are carbon comp resistors between the stages, that is a good sign, they're probably there to protect it from arcs.Proud Mary, do you have one of these?
Re: Wow, This VARIAN Multiplier is really cool !!
Proud Mary, Fri Mar 22 2013, 12:43PM
Steve is right to say that this Wallis stack was designed to be operated in dry air at atmospheric pressure. The equalising corona rings are sufficient to maintain stability - a nice smooth electric field gradient - so long as the stack is connected to a suitable load.
With no load the stack is likely to flash over any way it can, and be ruined in the process.
A happy load will have an equivalent resistance of 36MΩ/0.9kW i.e. 180kV/5mA.
If a higher resistance load is used, then (without the regulating functions of the right driver unit) the voltage might rise to the point of flash over, with likely damage to some of the diodes and perhaps some of the the capacitors too.
An electrolytic 'water resistor' could provide a good load if it is carefully made with good metrics.
Proud Mary, Fri Mar 22 2013, 12:43PM
Steve is right to say that this Wallis stack was designed to be operated in dry air at atmospheric pressure. The equalising corona rings are sufficient to maintain stability - a nice smooth electric field gradient - so long as the stack is connected to a suitable load.
With no load the stack is likely to flash over any way it can, and be ruined in the process.
A happy load will have an equivalent resistance of 36MΩ/0.9kW i.e. 180kV/5mA.
If a higher resistance load is used, then (without the regulating functions of the right driver unit) the voltage might rise to the point of flash over, with likely damage to some of the diodes and perhaps some of the the capacitors too.
An electrolytic 'water resistor' could provide a good load if it is carefully made with good metrics.
Re: Wow, This VARIAN Multiplier is really cool !!
the mad scientist, Fri Mar 22 2013, 05:33PM
That is amazing, much better than the tree CWs I made when I was like 15 (three years ago now). I wish I had one like that.
the mad scientist, Fri Mar 22 2013, 05:33PM
That is amazing, much better than the tree CWs I made when I was like 15 (three years ago now). I wish I had one like that.
Re: Wow, This VARIAN Multiplier is really cool !!
MRMILSTAR, Sun Oct 04 2020, 08:06PM
I have a chance to buy one of these at a good price. Did you every figure out how to operate it? Did you ever find any more specifications?
MRMILSTAR, Sun Oct 04 2020, 08:06PM
I have a chance to buy one of these at a good price. Did you every figure out how to operate it? Did you ever find any more specifications?
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