HV Power Source

[Cory Geesaman]

I'm playing around with a fluid-based Van De Graaff generator and needed a KV level HV source - since the subject has come up on here a bit in the past I thought I would post this link, as it seems pretty good ($40 with shipping to avoid the hassle of making your own drive circuit for a flyback transformer scavenged from a CRT or similar):

http://www.ebay.com/itm/MXA028-HIGH-VOLTAGE-DC-GENERATOR-BOARD-9-15-VDC-PROJECT-ASSEMBLED-KIT-/220905648130?pt=LH_DefaultDomain_0&hash=item336f00b002#ht_2299wt_1396 

[Simon Quellen Field]

Cheap negative ion generators are easily dismantled to extract the high

voltage unit. The high voltage output is what is attached to the needles

that emit the ions. The ones made for automobiles conveniently operate

from 12 volts, and can run from a nine-volt battery (or two in series).

If you need more current (unlikely) you can buy a laser power supply on eBay.

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On Mon, Mar 12, 2012 at 5:48 AM, Cory Geesaman <co...@geesaman.com> wrote:

I'm playing around with a fluid-based Van De Graaff generator and needed a KV level HV source - since the subject has come up on here a bit in the past I thought I would post this link, as it seems pretty good ($40 with shipping to avoid the hassle of making your own drive circuit for a flyback transformer scavenged from a CRT or similar):

http://www.ebay.com/itm/MXA028-HIGH-VOLTAGE-DC-GENERATOR-BOARD-9-15-VDC-PROJECT-ASSEMBLED-KIT-/220905648130?pt=LH_DefaultDomain_0&hash=item336f00b002#ht_2299wt_1396 

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[Mega]

There is a forum called Mosfetkiller. There they discuss the best
sources and cicuits and applications for HVoltage.

Unfortunately, it's only german I think.

On 12 Mrz., 13:48, Cory Geesaman <c...@geesaman.com> wrote:
> I'm playing around with a fluid-based Van De Graaff generator and needed a
> KV level HV source - since the subject has come up on here a bit in the
> past I thought I would post this link, as it seems pretty good ($40 with
> shipping to avoid the hassle of making your own drive circuit for a flyback

> transformer scavenged from a CRT or similar):http://www.ebay.com/itm/MXA028-HIGH-VOLTAGE-DC-GENERATOR-BOARD-9-15-V...

[Mega]

This http://mosfetkiller.de/?s=kaskaden
describes a cascade.

It's used for doubling, (depending on how much condensators u use...
*2 *4 *8 *16 ....) input voltage....

the only things you need are such condensators as shown and strong
diodes. Using two 9V Batteries -> 18V * x

[Mega]

Sorry, you'll need AC input as shown in the circuit.

You'll need a transformator from house-voltage (230V or 120V AC) to
some 10 or 5V AC and thereafter the cascade.

On 12 Mrz., 22:17, Mega <masterstorm...@gmail.com> wrote:
> Thishttp://mosfetkiller.de/?s=kaskaden

[Cory Geesaman]

Doubling circuits become too lossy for practical use around v*64 where v is the starting voltage so flyback transformers are a better choice for most high voltage applications in equally small form factors (still require AC).  I'm trying to get into the MV range for some experiments so I'm just using the 7KV-8KV flyback circuit from ebay as the injector for a liquid Van De Graaff generator.  I think flyback transformers can also handle a bit more energy/time than a doubling circuit (without getting into extremely high capacitances that also support high voltages [on the order of v*32 from the original voltage v]).  As a comparison, to get 7KV-8KV you would need a starting voltage of 109.38V-125V without accounting for losses, you would probably be safe going straight from mains in a doubling circuit, but I like the added safety of using a transformer to limit the overall current that can go through the circuit, especially so for things that can push harmonics back through the generator and change it's natural resonance/rate of charge.  A flyback circuit provides an oscillator that is usually separate from that of mains (usually of a much higher frequency than 60Hz), which provides the added buffer against undesirable surges of power when coupled with the saturation of the flyback transformer itself.  You could get around the safety issues and get a bit more of a variable energy/time by adding a mosfet-based drive circuit with an oscillator behind the input of the multiplier circuit (able to avoid being a passive circuit and detune from resonance to lower the throughput from it's maximum [determined primarily by the charge/discharge time of the capacitors]), but then you end up with something about as time consuming to put together as a drive circuit for a flyback transformer.  I just like the one from eBay because it's a cheap flyback circuit that comes pre-tuned and has a variable resistor to detune it if needed - no need to determine the resonance of a flyback you pull from a CRT or build any of the drive circuitry.

[Cory Geesaman]

I should note that my argument against pulling flyback circuits from CRTs is based around the fact I've always seen the flyback driver either epoxied onto the side of the CRT itself or built in line with a larger circuit board somewhere inside the casing - out of many attempts over the years, I've never managed to slice it out of a larger board or break it free of the CRT without damaging the circuit beyond repair, so my efforts to recycle flyback transformers have always involved pulling the flyback transformer itself and then sticking it in a network analyzer to find the resonant frequency and building a suitable drive circuit - so it's not my personal preference - but if you are able to remove the complete circuit in-tact then it might be a better option for you.  I do like the ion generator recycling idea as well, but I don't have any lying around and I can't see one breaking without the flyback circuit being broken, so I would expect $40 to be better than the $100 I typically see the things sell for.

[Simon Quellen Field]

Since you are just using the high voltage to seed the VDG, do you really

need a lot of current? I build normal VDGs (non-liquid), and the losses are

small, and while I generally don't need to seed them with extra HV, when

I have done so, a nine-volt battery into a negative ion generator worked fine.

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[Cory Geesaman]

My original idea wasn't to seed them with a current, though I hadn't realized liquid based ones had already been made until yesterday when I saw the links at the bottom of this response.  Van de Graaff's original patent actually had a similar mechanism to what you describe (using a low power battery to polarize the collector and draw the electrons out of the moving fluid using a pair of capacitive plates that form the collector (with a slight bias from the battery to drive them towards the collecting sphere).  A more recent paper (of which I've found no additional details aside from the first link below) details a design that is pretty close to lossless (the biased version I originally attempted was very lossy, so this is an attempt to actually get into the required MV power levels) - the seed power source is to power the injector of the almost-lossless version:

http://books.google.com/books?id=2sHghZ0pN5wC&pg=PA468&lpg=PA468&dq=fluid+van+de+graaff+belt&source=bl&ots=9FILQOVcZN&sig=bSgRgv45WSW33GryShWVmQArsG0&hl=en&sa=X&ei=EO1cT7bULIPX0QHhp6Ax&ved=0CFgQ6AEwCA#v=onepage&q&f=false

http://www.lateralscience.co.uk/VDG/vdgpat.html

http://arxiv.org/ftp/arxiv/papers/0804/0804.1764.pdf

[Cory Geesaman]

Oh, and to answer your question, no it doesn't need a lot of current in spite of being a bit more than a traditional bias - the HV generator I linked is pretty low current, and runs off a 9V battery.

On Monday, March 12, 2012 8:57:02 PM UTC-4, Simon Field wrote:

[Jonathan Cline]

On Monday, March 12, 2012 2:17:12 PM UTC-7, Mega wrote:

This http://mosfetkiller.de/?s=kaskaden
describes a cascade.

It's used for doubling, (depending on how much condensators u use...
*2 *4 *8 *16 ....) input voltage....

I posted my quick circuit layout for a voltage ladder (tripler) some time back.
Here's the link to the schematic, layout, and complete parts list for downloading.

HVPS for Systems Biology: A Low Cost, High Voltage Power Supply with Schematics + Board Layout

http://88proof.com/synthetic_biology/blog/archives/303

I used a european auto inverter (12VDC->220VAC) to feed mine, which yielded over 900V sustained, 1200V peak.  It is useful in certain situations, though there are limitations to this type of circuit.   Stay away from the leads when it is operational, and even for many minutes after powering it down (and even after forcibly discharging it).

I believe that MIT has students build these boards in certain EE lab classes.

I think it could be used for electroporation, however the plates would have to be precise gap width, and pulse duration would not be very predictable at all.   (Some papers suggest that pulse duration is not critical...)

Enjoy


## Jonathan Cline
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## Mobile: +1-805-617-0223
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[James Feeney]

Cory,

I have been looking at this. I'm thinking Tigon tubing, mineral oil, and stop leak powered aluminum radiator treatment for the metal particles. A small pump, HV source, and vioula liquid Van De Graaff  generator. There's technically no limit to the Voltage except leakage. The better you can control leakage, the higher the Voltage possible. Maybe instead of mineral oil, silicone oil. Then the challenge, where are you going to store those SuperHV charges? Whatever it is, it had better be inside a real good insulator. 

[John Griessen]

On 05/01/2018 11:04 PM, James Feeney wrote:
> I think it could be used for electroporation, however the plates would have to be precise gap width, and pulse duration would not
> be very predictable at all.   (Some papers suggest that pulse duration is not critical...)

Sure, my electroporator, https://github.com/kanzure/culture_shock, uses one stage of doubling.
It's driven by a python program creating pulse trains of sequenced duty cycle into the load, so the pulse shape CAN be controlled.
It behaves like a HV DAC with a little fish-tailing overshoot if you try to make it put out
over 50 kHz. Besides being an electroporator, the circuit boards can be a HV playground for tinkerers and engineers.
I'll be announcing it here when ready to sell.

If anyone is interested in doublers, I have a bunch of commercial HV PS doubler sections I can sell. They are all nicely spaced
out and hold charge for a good while if not bled off for safety. They are quite deadly when they have enough capacity to supply
more than the milliamps needed to cause fibrillation from an arm to arm shock...and I think these do.

[Tom Knight]

I would make very very sure that you had bleeder resistors direclty across all of your high voltage capacitors. Don’t let these systems kill you.
Be aware that common resistors have a voltage as well as wattage limit, typically 500 volts for carbon composition resistors. Use them in series if you need higher voltage ratings. Discharging capacitors is not enough — they can recover charge even after discharge.

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[John Griessen]

On 05/02/2018 08:44 AM, Tom Knight wrote:
> make very very sure that you had bleeder resistors

Culture_shock has bleeder resistors, plus safety interlocked covers.
Glad to see you're able to use this list again.

[Jonathan Cline]

A concern is the discharge coupling RF energy into nearby electronics which scrambles the microcontroller, resulting in random software behavior.  No joke.  Any part of the design using solid state electronics (that means anything with a microcontroller especially) should have significant shielding and ground isolation and redundancy.  The resulting errors would occur at random and very difficult to reproduce or troubleshoot yet could be dangerous because it would lead to unexpected program operation.  An analog electronics control circuit could be better, or at least reduce software's control over the final discharge.  Consider how much effort Toyota went through to attempt to debug the deadly Prius stuck-accelerator problem (and their internal investigation was forced by external pressure, several years after Steve Wozniak suggested there was a software bug in his own Prius) and still perhaps Toyota was unable to diagnose a specific semiconductor or software based fault in their design (at least publicly disclosed.. I'm sure their investigation found several unrelated software bugs which passed their original Q-A). 

For example.  Rather than the microcontroller and software directly controlling the trigger (entirely RAM-based logic and prone to faults), the microcontroller and software could reset an external timer chip which employs analog components to set specific periodicity for discharge and is design-limited by those components to only discharge after another time-window has elapsed.  Etc.   Fail-safes with built-in redundant fail-safes.

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[Cory J. Geesaman]

This is an amazingly old thread.  I tend to adopt the habit of wrapping wires around the terminals of capacitors when not in use (or discharging each time if the thing is developed enough to have a case on it.)  I don't trust bleeder resistors, they've burnt out on me in the past and hurt like all Hell when you misplace your trust in them.