Fusor Running, No Neutron Detection

For posts specifically relating to fusor design, construction, and operation.
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Mark Rowley
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Re: Fusor Running, No Neutron Detection

Post by Mark Rowley » Sun Feb 02, 2020 11:46 pm

Alan,
Three 30kV precip supplies only amounts to around $120 total. They can be purchased for around $40 a piece. That’s less than the cost of one 60kV supply or a months worth of going for a morning STARBUCKS coffee. Comparative to other disasters seen on this site over the past 20 years, yours is a mere hiccup, and a ultra inexpensive one at that.

Regarding your question of others who had problems. Early on I killed some circuitry in mine due to an arc over condition on the HV feedthru. Others here have killed high priced Spellmans and GHVR supplies under similar conditions. After replacing the components and beefing up the standoff potential of my feedthru, all has been good. There was also an issue of someone not potting it in oil as Finn Hammer highly suggested a couple years ago. The resultant arc over caused a similar failure. So the “others” you reference are just me and one other person. The other two people who used precips made successful Fusors and moved on.

I can’t weigh in on how yours failed unless I was there to see it in person. But I can say this...I only used the 30kV supply for brief time with the Fusor. After I detected neutrons and had the educational arc-over experience, I upgraded to the 60kV supply. So I don’t have any long term experience using the 30kV unit for sustained Fusor use.

Tbh, I think your larger problem is getting your neutron detection system going. I’ve made no mistake about my feelings towards the problematic nature of the Soviet 3He tubes. As a matter of coincidence a person on Twitter just messaged me last week about its inherent difficulty getting it to dial in.

I’d recommend forgoing a few more cups of STARBUCKS in exchange for another go at it and revamp your neutron detection efforts.

If it’s really a pure issue of no longer being fun, then obviously I can’t recommend any of this. Main reason I no longer play golf!

Mark Rowley

Alan Sailer
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Re: Fusor Running, No Neutron Detection

Post by Alan Sailer » Sun Feb 02, 2020 11:50 pm

Richard,

I'll try and address some of issues you brought up,

1) the flybacks ARE in series. A typical Chinese flyback is rated to output about 15kV. So two in series gives the 30kV rating of the supply. Back in the "golden "
days of American television flybacks (1970s) they made 30kV AC units. AC is much harder than DC so this was something else. Winding flybacks is an art form.
I would strongly agree that there is no problem with the output transformers. Under oil.

In air I have not tried.

2) I know of no design problems with the electronics. Execution may be a problem. Quality control IS a problem and may be THE problem with the units.

3) If I was not a lazy bastard I'd try and make another drive circuit. I'd get rid of the bootstrapping of the IRS2153 bridge driver and just put in a dedicated 12 volt supply.
I have no experience with turn-on dependent electronics and thus do not trust it. I would also try and shield the drive circuit from the output flybacks. In any case, I am
not a good electronics designer. I am a decent borrower...

4) I have not done a detailed evaluation of the old style large volume fusor vs the newer 2.75" conflat. It does seem that the later uses much less current. So flybacks
are an option for a good supply.

Now to philosophy,

In any project I try an balance the goal with the process. I am not at work making a living, get a degree or trying to solve the worlds energy problems. These are all
great reasons to suck it up and keep on keeping on. I do own a pair of perfectly fitting big boy pants :-)

In this case, however, nothing and no-one is depending on me to make this work. Not even my cat :-) So once again, failure is an option.

Finally, at this time I have about twenty years of actuarial time left on this planet.

Gotta pick my battles.

Cheers.
Last edited by Alan Sailer on Mon Feb 03, 2020 12:10 am, edited 1 time in total.

Alan Sailer
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Re: Fusor Running, No Neutron Detection

Post by Alan Sailer » Sun Feb 02, 2020 11:51 pm

Mark,

You have convinced me. I am a wimp :-)

And a whiny wimp at that.

Cheers.

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Mark Rowley
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Re: Fusor Running, No Neutron Detection

Post by Mark Rowley » Mon Feb 03, 2020 12:17 am

I’m hoping the dust will settle and you’ll continue.
We‘ve all had setbacks. No different than the recent one I incurred with the linear pinch project. We regroup and push ever forward.

Mark Rowley

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Richard Hull
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Re: Fusor Running, No Neutron Detection

Post by Richard Hull » Mon Feb 03, 2020 1:00 am

Mark's longer post above on this page is a very good one. It is all about picking one's battles, regardless of experience and ability to win battles, even if you are confident you can win them. At 74 one gets really selective.

To further my thoughts, I realize we tend to have a more gifted group of folks showing up here. We also have a cadre of real doer's here. We have a lot of people near expert level in at least one if not more of the disciplines demanded here needed to smoothly understand and do, picking up their softer points via osmosis and study along the way. It is unfortunately rare to see all points mentioned here rolled into one person. The young are especially vulnerable to lack of experience, lack of clear thinking, but mostly lacking in funds and often a negative attitude to their pursuit at home.

Nonetheless, a certain base level of all of the above in hand will always prevail.

I wish I had a dead chi-com supply like these to piddle with at the electronic level. I fear if I bought a new one I would go to extreme length to preserve and protect it. This is not the way to proceed to extend its capability. If I had one that was totally blown up, I would pull every component off and start by looking at the wiring at the HV end of the circuit board related to the flybacks. I would run one flyback by itself and see what it could do and if necessary, run it to destruction at the high output voltage level. what can these suckers do by themselves. Did the way they hooked them in series stress them? Did they just push them too hard?

I would work backwards from there. Suspecting they need a more aggressive and stronger drive system, even if it would cost more or be more complex.

There is much I do not know about what is done within these devilish supplies, but would love to explore.

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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