Flyback zvs plus multiplier

[Isaac Boehm]

Hello all, I was wondering if I could possibly power a D+D fusor with a zvs driven Flyback transformer connected to a negative polarity multiplier. I am not to keen on working with MOTs and I don't really feel like spending thousands on professional lab supplies. Any help wold be greatly appreciated.

[Carl Willis]

Hi Isaac,

This approach generically describes the design principle on which many of the commercial HV supplies operate. In terms of the hobby circuits floating around, the answer is a qualified "yes." The Mazzilli circuit (Royer oscillator variant) can deliver hundreds of watts; the half-bridge drivers sold by Eastern Voltage Research and Information Unlimited (their PVM-400) can likewise drive sizeable loads like a modest neutron-generating fusor, and are tunable via frequency control. Your biggest challenge will be finding a "flyback" transformer that has adequate ferrite and copper for the job. Trying to extract more than about ~50W from a genuine TV flyback will result in its failure in pretty short order.

Chirk, in Taiwan, makes some excellent potted transformers with gapped cores. They are not cheap in single quantity. Parts are not kept in inventory, but are wound to order; you must specify your own primary / secondary characteristics.

Suitable transformers can sometimes be salvaged from commercial HV supplies (e.g. Glassman).

Microwave ovens with switchmode power supplies have a very nice transformer, though the turns ratio may be a little low for your liking in a multiplier driver. Unfortunately, the switchmode technology is only found in the nicest ovens and hasn't percolated down to scavenging opportunities at the community recycling center. The OEM boards with transformers are available but prohibitively expensive.

Electronic neon power supplies have balanced gapped-core HF transformers that may be suitable for driving small balanced multipliers. The power supplies themselves are worthless for operating multipliers due to their phase-sensing protection scheme.

Finally, you can wind your own transformers.

-Carl

[Isaac Boehm]

I know a place near me that is a goldmine for vintage electronics I will look there. I know they have flyback of many shapes and sizes.

[Isaac Boehm]

Is there a chance I could just a the flyback with a diode to give me a negative output without using a voltage multiplier?

[Nick Peskosky]

I'm assuming your question was whether you could rectify the high-frequency HV output of the transformer secondary to achieve negative output polarity? Simply answered, yes. If you were to delve into the details a little more, you need to ensure that the diode(s) [in the case of a bridge] are properly selected to meet the PIV criteria of the secondary output and also have a fast enough recovery time for resonant driving frequency. Correct me if I'm wrong but you seem to be confused on the purpose of the multiplier topology. Full/half wave rectifiers accomplish conversion of a power supply's AC output to DC. Rectification achieved by multi-stage multipliers is a by-product of the additive DC output boosting accomplished by embedding capacitors within the diode network topology.

[Isaac Boehm]

I just went to the store and found a spellman x2068 0-30kv 200uA power supply. I am hoping to open it up and boost the amperage output and make the output negative with a diode.

[Isaac Boehm]

Its got a 15 pin connector and its model is cze30pn1000 I can't seem to figure out how to hook it up any help would be great!

[Troy Peterson]

I have easily gotten around 500 watts out of flybacks driven by the Mazzilli circuit... With an old large AC flyback from a big 70's era console TV.... Submerged in oil. My DC input was about 50v @ 10A from a very large power transformer that I believe came from a tube HAM transceiver. I fried one such flyback by running it in air, but a second identical flyback ran continuously happily under oil for up to 30 minutes under load. I never ran it longer than that, but I have no doubt that it would be fine. I also had success with home-made flybacks wound around large ferrite cores. Large ferrite cores are easy to find and easy to wind with a simple rig.


Cheers,
Troy.

[Richard Hull]

All of this chatter boils down to..... do you want to do fusion that is easily detectable with common detection methods? Yes if you find the right HV transfomrer. Yes if you can push about 300 watts into it. Without a transformer capable of 25kv out or more you will need a voltage doubler, at least.

The original query was for a simple flyback doing fusion. The answer is no.....Not without a good deal of power being pumped into it and some voltage multiplication.

Question......Help me out here.......Has anyone here, that is a member of the Neturon club, done verified fusion with a normal TV flyback as the basis for their supply? If so, chime in now. We seem to have this debate over and over about flybacks, ignition coils, etc.

Power is needed! Easy fusion detection might require 25 kv minimum, but realisitcally 30kv would be needed. With lower voltages, you will need decent current to make up for what you lack in voltage. 10 ma minimum with 15ma better. Thus, on the lowest end of fusion you will need 250-450 watts of power delivered. Assuming 85% conversion efficiency you will need about 300 watts - 530 watts into the transformer and circuitry.

There are, as Carl notes possibilities, but a lot of gotcha's must be met to make this happen. You are not going to use a simple TV flyback in air to do fusion that is readily demonstrable without a superior neutron detection effort.

Richard Hull

[Isaac Boehm]

i have the zvs working on low power on I flyback I have around the house. next step wind my own larger flyback and hv diodes and capacitors!

[Isaac Boehm]

After i wind my large flyback I am thinking of using this except in negative polarity

http://www.amazing1.com/products/003uf- ... citor.html

[Tom McCarthy]

Woahhh...How much do you have to spend?!

Tom

[Isaac Boehm]

Enough to build a neutron club worthy fusor.

[Isaac Boehm]

Sorry can't find this on the internet what equation do you use to calculate zvs wattage?

[Isaac Boehm]

I know no one has tried this but theoretically could I connect this http://www.amazing1.com/products/high-v ... 60khz.html to my zvs driver and use the output from it to go through a 30kv diode I have to get a negative output?

[Isaac Boehm]

I really need to know all this soon. Because of the shipping times.

[Nick Peskosky]

Isaac,

The rudimentary topology you're describing should work but you need to keep a couple key design considerations in mind:

1) Is the recovery time of your HV diode sufficiently fast enough to ensure it will not conduct in what should be the 'off-cycle' at the frequencies you intend to oscillate the driver at? This company extensively produces industry/mil spec standard axial lead SiC and Si HV diodes for use in multiplier circuits.

http://www.voltagemultipliers.com/

2) Have you considered the effects of the no-load/minimal load transition on your ZVS driver and how this repeated stress will impact your IGBTs/FETs?

3) How will you current limit the transformer's secondary so as not to prematurely saturate core or cause thermal/arc failure of the secondary winding insulation?

Some people in this forum have purchased products from Amazing1 before but I have no experience with them as a reputable seller. Best of luck in the power supply build.

[Isaac Boehm]

I understood most of that except the part about limiting the transformers secondary current. Do you mean I should add a current limiting resistor to it?

[Isaac Boehm]

I have looked on the internet found no data sheets on this diode. Its a varo H 315 930

[Andrew Robinson]

Just throwing it out there. I have hosted on my site http://www.teslamad.com/ a page for Paul Brodie to sell his flyback transformers to the Tesla community. I do this for free to help out the HV community. He gives discounts to Tesla Coil Mailing List users, but I'm sure if you're nice and mention you were directed there through me, he will extend the discount to you guys as well. He has all types of flybacks including lots of the huge open frame old styles. Check them out and grab um while you can. I purchased a bulk order a few years ago from him for a couple thousand (granted this was a TON of flybacks...) I still have a few left too if you're not able to get what you want from Paul. Good luck!

[Isaac Boehm]

Now I have got my whole system working. I have a 12 amp variac rectified to dc feeding 30v or so into my zvs driver. I am using a normal black plastic flyback witch is giving me an output of around 37 kv at 60ma or so (calculated using spark starting distance to voltage ratio chart). Now my question is could I just open up the flyback and remove the diode and flip it the other way round to get a negative output?

[Chris Bradley]

I have a 12 amp variac rectified to dc feeding 30v or so into my zvs driver.... witch is giving me an output of around 37 kv at 60ma or so

12 A x 30 V = 360 W
37 kV x 60 mA = 2220 W

.. something not quite right ...?

my question is could I just open up the flyback and remove the diode and flip it the other way round to get a negative output?

Too little information in how you are interfacing the output.

[Isaac Boehm]

Your right didn't realize that but the arc looks and angry and looks to be between 30 to 60 ma but must be more than 6kv.

[Tom McCarthy]

looks to be between 30 to 60 ma but must be more than 6kv.

Are you going on measurements or guesses?

Tom

[Isaac Boehm]

Guesses