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Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Fri Jan 19, 2018 7:48 am
by Samuel Low
As per the topic title, has anyone used this power supply before? The seller claims to have sold more than 20 units to fusor-builders in our community. I just want to know if anyone's touched this before and is it feasible or easy to use :)

It seems to take in 24VDC through a... D-Sub connector? Ups it to 30kV, I'm not sure if the polarity is negative though, if I'm to feed this into my inner grid core.

https://www.ebay.com.sg/itm/273023784926?ul_noapp=true

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Fri Jan 19, 2018 9:11 am
by ian_krase
400 uA is not enough for a fusor by almost anybody's estimation, though it might be enough for an accelerator.

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Fri Jan 19, 2018 12:06 pm
by Dan Knapp
I’m familiar with these supplies, but as the earlier replier stated, they do not produce enough current for a fusor. To answer your polarity question, they can be set for positive or negative via one of the pins on the D-sub connector. There are hundreds of these supplies out there as they are used in time of flight mass spectrometers as a replaceable module. Hence there are also many dead ones, so buyer beware. There is an identical Bertan model that was also used extensively in mass spectrometers. These are very well constructed and robust supplies for low current applications. I’m currently using them in an experiment that arcs a lot, and I haven’t zapped one yet. If your experiment requires under 400uA, I highly recommend this model.

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Mon Jan 22, 2018 4:00 pm
by Samuel Low
Thank you for the reply, Ian and Dan!
I think I've found a more suitable one, at 300W this would be about 10mA, I am hoping this amount of current would be okay.
https://www.ebay.com.sg/itm/high-voltag ... SwR29ZDZxS
What do you guys think?

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Mon Jan 22, 2018 10:32 pm
by Dennis P Brown
That is one small power source and I seriously doubt it can supply 10 ma at 30 kV. Also, that power level (even if it could) is very marginal for detectable fusion. More likely it will provide maybe 10 ma at 3 kV (its low range) and far less at 30 kV but I am guessing here. This unit was talked about here previously so do search for that thread. The shorting protection circuit, if I recall correctly, will make the unit not usable for a fusor. A fusor is often a direct short when first starting up. For the price it offers some interesting voltage and current capabilities but it has to be operated negative only - not sure if it uses +15 kV and -15 kV to get the difference for the 30 kV. That arrangement might not work for a fusor setup. It also says it does 200 watts in one pic so not sure their 300 watt claim is accurate. So, do check on these issues.

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Thu Jan 25, 2018 1:04 am
by Samuel Low
I see, thanks for the input Dennis! Is there an optimum current rating? As far as I understand it, the key variable in confining a good plasma is voltage since that sets up the strength for the electric field. Since current (with voltage) also determines the input power, is there a power rating that is best suited for "wall plug" use without compromising on safety?

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Thu Jan 25, 2018 7:14 am
by Finn Hammer
Samuel,

The supply you show is identical to the one I tested in this thread:
viewtopic.php?f=11&t=11992&p=78210#p78210
It is a relatively simple design, but it does deliver the advertised voltage and current.
Open circuit, it does not regulate down to zero volts.
The output is generated by two internally rectified transformers in series, and you can connect them negative or positive at your leisure.
I do not yet have a functional fusor, so I am unable to comment on it´s suitability as a fusor supply, but at least it does deliver voltage and current as advertised.
I hope someone will soon try it out.

Cheers, Finn Hammer

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Fri Jan 26, 2018 9:01 am
by John Futter
Samuel
you need to do a lot of reading on this site
you will need a correctly calculated ballast resistor to get around the problem that Dennis has highlighted of the near short @ startup

there is plenty of info in this forum on this, many of them from me.
And no I am not going to repeat why this is necessary

Re: Has anyone used the Spellman X3000 50V-30kV 400uA Rev E7 24Vdc

Posted: Thu Feb 01, 2018 6:09 am
by Samuel Low
Hi Finn, thank you! I will remember your post and direct anyone else to see it if they ask about the same HV supply.

Hi John, thank you, yes, I have built 2 demo fusors in the past and have calculated an adequate ballast for them :)

I must admit I was a bit careless about the first one, where the "transient" shorting of the fusor as the electric field was setting up, did cause some damage to the transformer although the plasma still formed in the end. I have been wary of that ever since.