Spellman DF3 Power Supply Fusor Application

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Re: Spellman DF3 Power Supply Fusor Application

Post by John Futter »

Good
i've been caught before
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

Ironically, I got an X-ray of my knee today and their device used the same type of connector! I should've asked the tech to tell me how to connect it. :-)
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Richard Hull
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Re: Spellman DF3 Power Supply Fusor Application

Post by Richard Hull »

Sadly, many among us here could rip the top off that thing and search for the single little logic line that is at a logic one or a logic zero which alerts the over-watch circuitry that says "there be filament here!", and tie that line down forever to that "fils OK line.

Alas, we are not there and can't guide you in our remoteness.

Dare you try to fake it out with a well insulated, highly isolated air of oil cooled glow-bar resistor so it thinks it has a filament load??? (that resistor will be deadly electrified against ground to the full negative HV potential.)

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

I've opened this thing apart and disassembled it to some extent before, but without circuit diagrams, figuring out which thing controls the filament error would be a pain in the neck. I suppose I could retrace what circuitry turns on the front lightbulb during this error, but I'm trying to avoid that for now.

Anze
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Dennis P Brown
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Re: Spellman DF3 Power Supply Fusor Application

Post by Dennis P Brown »

Wouldn't a cathode in a fusor be equivalent to a filament? That is, simply use a small wire cage in a vacuum chamber (metal) and place that under vacuum. At high vac it should allow full voltage stand-off and the said cathode would then be seen in the 'logic' as a filament?
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

Excellent news! Upon Rex's fine idea of stripping more of the wire mesh and black stuff from the cable, I did so. Pictures below.
cable.jpg
I actually only stripped the metal wire mesh but I figured I'd re-measure the resistance of the black mesh too and across that entire 6" length, it was only 10k Ohm! Last time I measured it was at 11pm on a thursday so maybe in my drowsiness I set the range to Giga Ohms and it read 0, but seeing as it is not a good insulator, I cut that off too and now I believe it could have been shorting to that! Because I removed the wire mesh before, although not 6", but never the black layer, so it was less than a quarter-inch removed from the bare C wire.

Then I tried two tests (so far). First was leaving all three wires disconnected from each other (L, S and C disconnected). It ramped up to 15kV normally with no arcing but I got mA Regulator error and Fil. Cur. Limit. So again, I figured with no load across L and S the thing doesn't see the filament and spits out these errors. So I shorted L and S, leaving C disconnected, which usually resulted in arcing, but this time it did not! In fact, all I got was the OPEN FILAMENT error and the supply shut down. For the sake of everyone, I am also attaching a screenshot of the manual's error subsection.

Overall, getting rid of arcing is fantastic, it just seems to me now that I have to connect L, S and C in such a way as to trick the supply thinking there is a filament there. Once that's done I will be ready to, dare I say, rock n' roll!
manual errors.PNG
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Richard Hull
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Re: Spellman DF3 Power Supply Fusor Application

Post by Richard Hull »

To answer Dennis' question about the cathode of the fusor acting as a filament equivalent.....

NO! A filament is a high current closed loop as in the x-ray tube. Two of those three wires are expecting a multi-ampere burning filament load and the supply checks for that load. If it is not there, the system figures the tube is absent or the filament is burned out, and thus, will not allow the HV to be brought up.

The cathode/grid in a fusor is not a filament in spite of it being part of a closed, conductive gas circuit for the high voltage in the milli-ampere range during normal operation.

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
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

I think we figured it out. I connected L and C and left S disconnected and just cranked up the filament current to 0.9A. Since as mentioned before, the filament output screen keeps showing 0.88A no matter the settings (I always had the knob for filament current set to 0, I don't know where 0.88A comes from), so I figured just above that should work. Well it does! It went to -15kV with no errors or arcing and stayed there for 30 seconds! Hopefully this all works when we connect to the fusor.

For now, thank you all! I very much appreciate it!
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Re: Spellman DF3 Power Supply Fusor Application

Post by Rex Allers »

Anze,

Good catch on the conductive black layer of the cable. I did not know and would not have expected it. I just measured the cable I used to take pics of the cut-back. I wrapped some wire around the black material near end (for good connection all the way around) and measured resistance through the ~6" of unbraided length to the remaining braid -- less than 2k ohm.

In retrospect, in that pdf for the cable I posted earlier, '2214.pdf', it looks like the black layer is 'D' in the drawing which has the text "SEMI CON EPR", so semiconductive, I can now gather. Great that you figured that out.

-----
On the C, S, L pins of the HV connector... It looks like I misinterpreted the manual's text that I found in an odd place. Today I was looking at Spellman web pages and found clearer wording in the data sheet 'DF-FF.pdf'.
  • Output Connector:
    75kV, 3 conductor Federal Standard X-ray connector. -60kV is connected to terminal “C”. Terminals “S” and “L” are jumped together. The filament output is connected between terminals “C” and “S”. Other configurations are optional. (On the FF3, all output connections S, L, & C are connected together).

So that HV wiring figure I drew in my first long post was wrong. It looks like the XLF one you put in your first message of this tread is correct for the DF3 too. Sorry for the bad info I provided from my misinterpretation of the wording in the DF3 Instruction manual. I would edit my earlier post to fix but seem to be past the time where I can do this.

-----
I'm not sure if you have noticed one short paragraph in the "OPERATING INSTRUCTIONS" section of the Instruction Manual about Presetting operation limits. This one:
  • J) Presetting: Depress and hold the X-ray
    off switch. The kV, mA, filament current limit
    and maximum tube power limit can now be
    preset. NOTE: No output will be generated
    even though the meters are displaying in the
    preset mode. It is suggested to set kV to a
    minimum value, (10 kV-20kV). If kV is set too
    low the kV MIN indicator will illuminate.
    Simply raise the kV level if this occurs. Set mA
    level to a minimum value (5mA). Filament
    current and tube power limit should be set as
    required by the X-ray tube manufacturer.
    Release the X-ray OFF switch.

So I am wondering, maybe the Filament current knob on the front panel only works, during this configuration process, to set this max limit? Maybe that is why you always see .88 A in operation. Maybe the max power knob also only works in this presetting mode.

It might be worth trying to enter this Preset mode and see what the present values are, then set Max Filament current to some very low value rather than waste a lot of filament power with the shorted connection you seem to need to get active HV.
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Re: Spellman DF3 Power Supply Fusor Application

Post by John Futter »

Aha
again the black stuff comes to haunt
told ya
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

Yup, thanks John! I knew someone mentioned it. Appreciate it.
Really happy it works now!
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

I've figured out the supply, so I need no additional help (for now), but I will post all the data I have collected here. That way, it may be helpful for other people in the future. I have also had some good conversations with Spellman engineers so I am posting those too, in case you can infer some wisdom from them.

Plug on the back of the device has three pins (C = common, L = large filament and S = small filament). In my situation, the high voltage had the following color coding: L = Yellow, S = Green and C = two bare wires.
PIN OUTPUT.PNG
There is a ground post on the back of the supply, that is what the -60kV is with respect to. All three pins (L,C,S) measured an impedance of several Giga-ohms with respect to ground. L and S are internally shorted (stated in the manual and tested) and the impedance from L/S to C for my supply is about ~470 Ohms. When trying to configure this supply as a fusor supply, I ran several configurations of wiring of L, C and S. Below are the configurations and the errors I got with them. The definitions of errors are in the DF3 manual which is easily found online and I also posted the screenshot of errors in this thread a few posts back, so use that for your reference.

L, C, S disconnected with each other (current set to 0): mA RGLT ERROR, FIL. CUR. LIMIT

L, C, S disconnected with each other (current set to 1mA): mA RGLT ERROR, FIL. CUR. LIMIT, OPEN FILAMENT

Only L and S shorted (current set to 0): OPEN FILAMENT

Only L and S shorted (current set to 1mA): OPEN FILAMENT, FIL. CUR. LIMIT, mA REG. ERROR

What ended up working for us was L and C shorted and S disconnected, although since L and S are internally connected, that sort of just implies all three are shorted, which to some extent makes sense, when looking at the picture below provided by Spellman on how this supply operates.
df3 connection.PNG
Even with this configuration, (L and C shorted), we got the same mA REG. ERROR and FIL. CUR. LIMIT, what ended up working was cranking the "filament current" knob to 0.9A. Reason being, we noticed that no matter the settings, when testing the supply and the voltage was rising, the front panel filament current knob read 0.88A, so we just went slightly above that. I am not sure why that happens, nor do I care since that part is irrelevant as long as we have control of voltage and the mA. And, actually, writing this out, I am curious if that 0.9A filament current setting would also solve the issue in the previous configurations, I'll try next time in lab.

Here are the responses I got from Spellman that intricately describe how this unit operates:

"The DF3 is a negative polarity/floating filament X-Ray generator. See attached product data sheet and a couple of slides from an internal training class I teach. The DF was designed to operate X-Ray tubes under closed loop filament control. The customer provides a 0-10Vdc signal (from either the local front panel or remote interface) that represents 0-80mA and our internal closed loop emission control circuitry adjusts the output of the floating filament supply to provide the desired current emission current. There a timing sequence of bringing up the high voltage, ramping up the filament, over and under current faults, regulation error fault, filament open fault, filament short fault and other protective circuitry to assure proper operation. This was all done to protect the X-Ray tube. There are probably other issues that I’m not aware of as I’m not the DF product engineer. Trying to operate the DF unit in a non-X-Ray generator application will create some if not all of the above mentioned faults and perhaps other problems, preventing operation. This unit was never intended to be used in a non filamentary controlled X-Ray generator application."

"The DF/FF unit is used in both negative and positive output polarity.
In negative output polarity a floating filament is required so the additional pins on the Federal Standard 75kV 3 pin X-Ray connector come in handy.
In positive polarity a ground referenced filament is used, so we just tie the high voltage to all three pins, so they are all at the same potential."

"DF unit in negative output voltage so it has a floating filament, hence the use of the multi-pin Federal Standard X-Ray Connector. C = common, L = large filament and S = small filament. Filament current flows between common and Large/Small. The filament is a floating filament, one side is connected to the common so the filament if referenced to the high voltage output voltage. Filament is connected between the C and the L&S pins.

"FF unit is positive polarity so it has a ground referenced filament, connected on a rear panel terminal block. Since only one high voltage connection is needed all the pins are tied together."

Hopefully this helps other people with similar supplies. Overall, this thread became a wealth of information that helped me immensely and I hope it can do so for others. Thank you everyone!
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Re: Spellman DF3 Power Supply Fusor Application

Post by Rex Allers »

Anze,

Thanks for sharing the details and glad you have found a configuration that works for you.

I'm wondering if you had a chance to see what 'Presetting' values are set in your supply? (I mentioned this, quoting from the manual paragraph, in my last message.)

If you don't have time to do any more looking now, I understand.
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

The presetting values are just the values the supply is set to before it's turned on. You press the X-RAY OFF button to show them, set them, then press X-RAY ON button to turn on the supply and it will slowly ramp up to those preset values.
The filament current was always set to 0 in the preset. Once I went out of presetting mode and turned it on (X-RAY ON), it jumped to 0.88A. That's why it makes no sense. The Kilowatts knob under "preset" is set to the minimum, because if at 0, the supply automatically gives you a "OVER POWER" error on the front panel. Funny enough, just for a test, I cranked up the Kilowatt knob so it was a bit higher than usual, just to see if the filament current would change from 0.88A. It did not...
The kV and mA are preset via my LabView script.
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Re: Spellman DF3 Power Supply Fusor Application

Post by Rex Allers »

Thanks for sharing the preset info and behavior. The filament current you see seems illogical but it is what it is.

I would think when you get to actually drawing current on the HV, you might need to set the kilowatt limit preset a bit above expected operating values.

I wish you good luck on getting to a situation where you can actually try it.
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

Another update for those interested: this power supply, as mentioned before, can start with a minimal voltage of 15-16kV. Anything below it shuts it down on startup ang gives the kV min error. Anyway, the interesting part is, once you get to the 15-16kV and it stabilizes, you can then lower down to about 8.5kV before it shuts off with the kV min error. I will say, it's hard striking a plasma with 8.5kV minimum, it's easy for it to runoff with the current forcing me to shut it all down or I catch it and lower the pressure but then it stalls and extinguishes. Not to mention, once plasma ignites it creates like a mini-EMP or something which often shuts off a lot of our equipment, the camera in particular. Will do more testing though.
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Re: Spellman DF3 Power Supply Fusor Application

Post by FusorFellow »

Hello all,

I am new to fusors, and I have the same power supply as in this thread, the Spellman DF3, but I can't get it to output any voltage. Not only does the front panel not show any applied voltage, but I have a high voltage probe attached to the C pin, and the ground wire of the probe connected to the power supply chassis, and it does not show any voltage either. But strangely, it does not give any errors on the front panel either. Currently, my HV x-ray cable is intact, and I have not cut it open yet, as I first just want to test if the power supply works.

I have connected jumpers according to page 10 of the DF3 manual, in figure 3.1E, to disable remote operation, so that I control it with the front panel. If you do not have the manual handy, the overview is that I have connected jumpers to connect pins 2, 3, 5, and 20 together, a jumper to connect pins 1 and 11 together, and a 28V, 1W failsaife interlock lamp across pins 22 and 23. When I push the "x-ray on" button on the front panel, the failsafe interlock lamp does light up as it should, but the front panel gauges don't show any change in measured readings of voltage or current. Everything stays at 0. The maximum settings I have adjusted it to when pressing in the "x-ray off" button are: 20 milliamperes, -10 kV, 2 filament amperes, and 1 kW. I have also tried connecting a 20 ohm, 15W resistor across the L and S pins to try to simulate a filament, but that did not make it work. Then I tried connecting the resistor across C and L, and then C and S pins, and that did not work either.

I did measure between each pin at the output end of the cable and the power supply chassis, and all of them measured as an open circuit, so there should be no issue there. One strange thing, however, is that when the cable is connected in to the power supply, at the output end, I measure continuity between every two combinations of pins. As a qualitative measurement, each combo of pins measures as about 0.1 ohms. It seems like this could be the problem according to what I have read in this thread. But strangely, I do not get any error codes from this. With the cable disconnected from the power supply, there is no continuity between any two pins. The next thing I though of trying, but will attempt tomorrow, is to thoroughly wipe and clean the inside of the connector on the power supply to see if the clear grease smeared inside at the connection point was actually a conductive grease, instead of a dielectric grease, which is causing a short.

The entire time I have tested it, the only message lit up on the front panel is "INTLK CLOSED". I do not get any error messages with anything I have tried.

As some extra context, this power supply came from eBay, and was already used.

Thank you all for your help in advance.
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Re: Spellman DF3 Power Supply Fusor Application

Post by Rich Feldman »

Welcome, Bill. Someone else can send you the pointers about how to change your handle from Fusorfellow to Billjohnson. Or just read the contemporary Rules thread.

This thread makes me want to pick up where i left off on repairing my Spellman. As received via Ebay about 4 years ago, it blew the line fuse when turned on. I replaced some failed diodes and maybe DC bus filter capacitors. Separate from that, the control circuit powered up OK and I got some successful dialog using the control bus. I think it's Ethernet, with an 8P8C modular jack casually called a RJ45. I had to get a crossover cable instead of regular cable.
All models are wrong; some models are useful. -- George Box
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

Of course, just as I am getting good results, stuff goes wrong.

So yesterday, the DF3 power supply worked great. We were able to get a 16.6kV plasma, higher than ever before in a new chamber. Stable, everything was working fine.

Today, I start the power supply, without touching anything from the last test, and as its voltage ramps up; shuts off. Gives me the FILAMENT CURENT LIMIT and mA regulator error. What I am seeing is that the filament current starts at 0.88A and just starts rising and rising till it shuts off. Yesterday, it just stayed at 0.88A for the entire duration (I have video to confirm).

I am so utterly lost as to what could be causing this. I even set the filament current to 3.11A to see what happens and it just rises from 0.88A to that and shuts off. Does anyone have any clue? Again, same configuration, same everything worked yesterday...

Anze
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Anze A Ursic
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

And now all of a sudden it works - go figure. Sometimes it ramps up to the voltage and the filament current stays at .88A, sometimes it jumps to 2.5 and goes down, sometimes to 1.5 and down. Sometimes the thing doesn't even start. Oh the joys of trying to achieve nuclear fusion!
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Re: Spellman DF3 Power Supply Fusor Application

Post by Matt_Gibson »

This is why I decided to go the homebrew route for my power supply. A lot more work but much easier to figure out what’s wrong.

-Matt
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Re: Spellman DF3 Power Supply Fusor Application

Post by Anze A Ursic »

Matt,

yup... but at this point I'm just trying to finish this project and if that power supply died or something, I'd lose my mind, since the entire remote control / monitoring system is built for it and would take weeks to re-purpose for another type of power supply. Hopefully it just works enough for me to get fusion...

Anze
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Re: Spellman DF3 Power Supply Fusor Application

Post by john_auerbach »

Hey everyone, my name is John and I am a 4th year undergraduate who inherited much of the system from Anže to conduct some ion propulsion experiments in the chamber. At the moment, I am trying to reconstruct the old setup on my own, and everything seems to be working perfectly except this power supply; I haven't been able to get it to turn on at all.

I have it fed with a proper 220V, and the interface I have it wired to registers when I turn the CB1 circuit breaker on/off. It's definitely receiving power and connecting to the interface, but the front panel display remains off when I press CONTROL POWER ON.

I discharged the system and checked all the fuses, but couldn't find anything wrong with them - I suspect it might be an issue with the external pin connections for our interface. I checked to make sure the interlock was closed, so I'm not sure what might be causing the problem.

I'll go back through the manual a bit more and see if I can find anything else, but any advice would be greatly appreciated.
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Re: Spellman DF3 Power Supply Fusor Application

Post by Dennis P Brown »

First, you need to start your own new post with this question rather than use an existing one.

One (and my only) experience with a Spellman was if the jumper on the back is not installed the unit will not power up. This simple issue did not generate a code nor show any obvious issue except the unit wouldn't power to 'On'. Elementary problem and unlikely for any new unit but surplus is often modified such that the jumper has been removed. In any case, the manual will show the details for the jumper wiring on the back of the unit - simply make sure that is installed.

Hopefully, this is all that is wrong but others here will likely add more info especially if you create your own thread.
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Re: Spellman DF3 Power Supply Fusor Application

Post by vince_Darmancier »

Great thread ! with a lot of helpful tips! I just found a DF3 60Kv 80mA. Just waiting for the delivery, it looks like all these troubleshooting will come very handy indeed! My new (1987) Glassman is such a pain to work with, I fixed it 3 times and bypassed so many safety features i lost count! it still works ...when it wants too .. anyway, I`ve made another fusor for a new video and will post here for updates . Thanks Anze and everyone here! Again!
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