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Re: Neptunium's fusor progress

Posted: Wed Jun 12, 2019 4:52 pm
by Richard Hull
Many of these custom or even stock HV supplies have all sorts of lockouts for customers to wire trip switches in cages etc to prevent operation if a cage door is open. Arcing is a possible killer of a supply and will certainly shut a supply down immediately. Again, no real HV supply ever made in a professional scenario is designed to work a flaming arc. Some can't survive a flaming arc drawn.

Richard Hull

Re: Neptunium's fusor progress

Posted: Wed Jun 12, 2019 5:43 pm
by Dennis P Brown
If it is tripping because of a run away current, what ballast resistance are you using in your fusor circuit? My system would surge over 100 ma at startup but I had a simple x-former and diodes so not an issue; I did have a ballast resistor in my circuit and it was both the ohm and wattage Richard recommended but a fusor can act much as a dead short for a fraction of a second. That can trip any feedback system for PS that have that feature so that might be the issue.

Re: Neptunium's fusor progress

Posted: Thu Jun 13, 2019 1:07 am
by Bob Reite
Got to be built like for old school tube transmitters in which tubes have arcs that are dead shorts for an instant, yet don't kill the tube as long as it doesn't last too long.

Re: Neptunium's fusor progress

Posted: Thu Jun 13, 2019 6:45 am
by John Futter
I have no knowledge of this unit
but
many x-ray supplies are setup to turn off when the the tube arcs to save the tube
other supplies notably Spellman have arc counters on ordinary supplies to protect the diodes and capacitors in the multiplier stack from overheating from dV/dt events.

As has been already asked what value is your ballast resistor ie somewhere between 50kohms and 200kohms. If you do not have one read up on what you need before you destroy your power supplies

Re: Neptunium's fusor progress

Posted: Thu Jun 13, 2019 10:23 am
by vince_Darmancier
No this is not a ballast issue. i am not at that point yet. i have read on ballast for the current surge and i am still working on that.
The HV does not power on its own i have to physically hold the magnetic contact to get it to power up.
I have another Glassman positive 40Kv that works great and never trip even when starting up vacuum tube or with a spark gap..although it might have an internal protection, it does not have a HV power switch.
This larger unit on the other hand is capable of 50mA and when set to maximum current trips with the first weak 20kv spark.
and thats only when holding the connector down .
You might be right about the arcing protection, but for now i am just trying to get it to power up normally without holding down the connection inside.
Rex suggested looking at other Glassman units and i should take the time to do that, their probably wired the same way..

Re: Neptunium's fusor progress

Posted: Fri Jun 14, 2019 6:27 am
by Richard Hull
As I mentioned before, you may have a plug or barrier strip on the back of those units. Some HV supplies offer that remote safety switch option. As such, you may have to short two pins on a plug or barrier strip before HV will allow that relay to pull in. If this is the case, an owners manual would mention that fact. I own a Glassman with that feature.

Old Universal Voltronics supplies also had a number of tricky gottchas that would not allow the supply to power up. Most notably, if the filament in the HV "ON" light was blown, the supply would not come on.

Richard Hull

Re: Neptunium's fusor progress

Posted: Fri Jun 14, 2019 9:21 am
by John Futter
By golly
Richard I had forgotten the rules for x-ray supplies
yes you had to monitor the HV on /enabled and the x-rays on lamp currents to make sure that these were lit when activated otherwise the supply would not let x-rays be produced.
All a bit inane in this modern day of LEDS but we still have to put this circuitry in even for
LEDS.
yes the interlocks need to be in the right logic state to let the psu operate there well could be two or three circuits two being short to enable and one open to enable with all having to be true for the big relay to pull in

Re: Neptunium's fusor progress

Posted: Fri Jun 14, 2019 9:13 pm
by Richard Hull
Yes, when I was in Tesla coiling, one fellow in our group was tickled while monkeying with his Tesla coil's primary circuit due to the variac, turned down, still supplying 1 or 2 volts to his high voltage 14,400 volt transformer. Determined to never let that happen again, he rigged up a micro-switch under his seat cushion at his coil's master power control panel. This meant his butt had to be in the seat, away from his Tesla coil, before line AC would even reach the coil's main panel's on-off switch and contactor!

Richard Hull

Fusion claim and neutron detection

Posted: Mon Dec 02, 2019 8:05 pm
by vince_Darmancier
Hi everyone.
Today was a great day as i received a neutron counter !
neutron detector 004 resized.jpg
it is rather old (1986) from Texas Nuclear, but still appear functional. The background is about 1 neutron every 5 to 7 minutes.
This unit has the detector permanently lodged inside the moderator (big black sphere) so i cannot separate the two.
neutron detector 003 resized.jpg
Although it has not been calibrated in a while, I just wanted a reliable neutron detection device so it is sufficient for my purpose.
neutron detector resized.jpg
So i put it to the test and here is my result.

i vacuum down the chamber and applied high voltage to the grid (just air)
a few neutron popped up around 10 to 15 Kv but stopped beyond that. the xrays went wild over 20 kv and i beleive some (2 or 3 ) triggered the neutron counter.

i then pushed to vacuum down to 1.6x10-4 Torr and introduced a tiny bit of Deuterium.
when the pressure stabilized to 1 micron i turned on the high voltage which raised the pressure a bit to 20 to 30 micron .
after a few seconds it moved up to about 50 micron (due to heating)

at this point the voltage reads about 20 Kv at 25 mA and the neutron counter went up to 200 counts..

beautiful bright star mode too!

I should mention that the moderator ball is about 3 feet from the fusor.

because the fusor gets so hot so fast i stopped it to record these data.

I tried again and just under 20Kv at 25mA the total counts went up from 209 to over 300 in a few seconds..

I will have a video soon that will explain all of this in detail...
for now i am waiting for that thing to cool off a bit.
last friday (before the neutron counter delivery) i have detected the 20Mev peak with my gamma spectroscopy system.
I hope these are all good sign and i will be happy to provide more info as requested!
Vince

Re: Neptunium's fusor progress

Posted: Tue Dec 03, 2019 3:58 am
by Paul_Schatzkin
Vince,

I was poking around in the forums this evening and just discovered that the images from your first posts in this thread are among those that got disappeared when our previous ISP mangled the site before we moved it.

If it's not too much trouble and assuming you still have access to the images, would you please go through your first posts and restore the images?

I have elevated your user status to "senior" which should give you the access you need to edit old posts.

I am making this special request because you are among the more recently active members, so your posts are showing frequently in the "Active Topics" listings. It would be helpful for newer members to be able to see the images that accompany the posts that track your excellent progress from newbie to neutrons.

Thanks,

--PS