Spellman Power Supplies

This forum is for specialized infomation important to the construction and safe operation of the high voltage electrical supplies and related circuitry needed for fusor operation.
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Emrys Peets
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Spellman Power Supplies

Post by Emrys Peets » Thu Nov 28, 2019 7:18 pm

Hi all,

I have just cancelled a HV power supply order from Spellman that was -20kV, 15mA because I was worried Id have too many problems in detection. Now I am looking into the 600 W SLM SERIES and was wondering if there is a voltage/current configuration anyone prefers. Ive asked for quotes on -40kV15mA and -30kV20mA. My gut feeling is to go with -40kV as it will be less likely to destroy my grid/higher probability of fusion, but I was wondering if there are arguments to be made for the -30kV option.

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Bob Reite
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Re: Spellman Power Supplies

Post by Bob Reite » Thu Nov 28, 2019 11:02 pm

I personally would opt for the 50 KV 12 mA supply. Yes, if you are ordering it brand new, expect a quote in the USD thousands.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.

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Re: Spellman Power Supplies

Post by Andrew Seltzman » Thu Nov 28, 2019 11:31 pm

See if this seller will sell just the negative output version.
https://www.ebay.com/itm/LNR0311-SPELLM ... SwJhdbkGRi
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Joe Gayo
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Re: Spellman Power Supplies

Post by Joe Gayo » Fri Nov 29, 2019 1:14 am


Emrys Peets
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Re: Spellman Power Supplies

Post by Emrys Peets » Sat Nov 30, 2019 8:22 pm

Thank you all for the help! I should also ask Spellman about -50/12 that never crossed my mind.

I had seen the ebay posting but was concerned about only running with 5 ma. If the prices are reasonable from Spellman, I may end up buying the -40/5ma as well.

Robert Dwyer
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Re: Spellman Power Supplies

Post by Robert Dwyer » Mon Dec 02, 2019 6:16 am

Hello Emrys,

-40KV @ 5ma should work well enough considering you have sensitive enough counters, or long enough runtimes for Bubble Dosimeters or activation foils to pick up a reasonable signal. I ran my fusor with a -50KV 5ma Hipotronics supply. In its early life I tried to keep my voltages lower that ~35KV out of a fear of X-Ray leakage (no lead shielding at the time), but still detected neutrons with a bubble dosimeter at those power levels, of course with long (20-30 minute) run times.

I agree with Richard though. If you have the funds I personally would go for the 50/12 as you won't be as constrained with the 40/5, if you get worried about grid destruction you always can run at lower powers but if you find yourself ending up wanting to push your system (which I found myself doing very quickly and I am sure others can attest to that feeling), you will be glad you chose the higher power supply.

Good luck on your power supply hunt! Glad to see you have taken an interest in building a fusor!
If we throw more money at it, it will have to work... right?

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Richard Hull
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Re: Spellman Power Supplies

Post by Richard Hull » Mon Dec 02, 2019 8:33 am

Robert is right on! We all want more neutrons and more fusion. This only comes about due to power and in any HV supply this means a warranted steady available current, regardless of voltage. The minimum to push upwards is 10 ma, but 30 ma capability is none too high for the advancing amateur.

With the above said, if you can't roll your own high current HV supply, you will have to a have roll of cash in your pocket to plunge deeply into the upper regions of fusion. There is rarely a supply out there that you just sort of fall into that is plus-ultra in every respect either free or with little outlay of cash, provided you are willing to stand around and wait. If however, you are in a hurry and got the fusion bug bad, you will have to pay big money for big fusion.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Bob Reite
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Re: Spellman Power Supplies

Post by Bob Reite » Tue Dec 03, 2019 1:37 am

I'll also add that if you are just going to throw money at it and order a brand new supply from Spellman, they do not stock that I know of, they build to order with a typical lead time of ten weeks. If you are good with high voltage electronics, you can probably do it in less time, although the lead time for some of the high voltage components needed is about four weeks.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.

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