XRay Tank- any ideas about what is inside

[HighVoltageRulezz]

Hi-

great forum- I am new here and already learned a lot! Thanks.

I salvaged an Xray tank from a HF Xray Power Supply but have no clue how exactly it is connected inside. I do not want to open it, because I am worried to trap air bubbles, so does anybody have an idea what could be on the inside?

It has 2 big and 8 small (9, including a ground stud) connectors on top.

What drive frequency woud you expect? And how to drive it? Fullbridge and a capacitor (additional inductor?) in series to the primary of the tank?

All help would be really appreciated!

Thank you so much in advance
Roman

[Mads Barnkob]

Hi Roman and welcome to HVF!

X-ray high voltage generators are pretty standard on the inside for the type you see here. It has the age to be SCR inverter driven or maybe even mains voltage directly.  The operating frequency on the SCR driven are somewhere between 2-5 kHz.

The black and blue wires are the primary connections.

If there is a bridge between two terminals, that is mostly likely the center point where you can insert a shunt resistor to measure the current in the mid-point grounded HV transformer secondary side.

All the terminals to the left connecting to the PCB is voltage/current/temperature feedback from inside the tank.

I did a teardown of a Siemens x-ray head with built in high voltage generator and maybe you can learn something from that:

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You can also see some details on a older x-ray high voltage transformer, along with inverter here:

[HighVoltageRulezz]

Thank you so much for the quick and helpful reply!

I am pretty sure though, that it has a higher working frequency- it is pretty light (probably around 20kg) and was connected to a bridge of pretty fast IGBTs before (actually the same IGBTs work in my DRSSTY now  )
I once had a 50Hz unit- pretty sad that I had to sell it but it was huge weighing over 100kg but the ease of use was wort it  (Used it to drive my Fusor a while ago)

Do you perhaps also have an idea what the frequency might be for this unit considering it is "high frequency"?

And- can I leave all other pins besides the input wires floating (I guess the ones you mentioned for current measurement have to be bridged- in my case probably the ones connected with the Diodes)? Perhaps even better- let the PCB connected and do not care about the left connections?

Furthermore- what about the tube filament supply? I d expect that to be an extra transformer like in your video, so it would also have to have two contacts routed to the outside?

And- can I run it un-ballasted on the output side or do I need some resistors to protect the multiplier inside in case of arc overs?

Sorry for all the questions but I really do not want to ruin this awesome supply and plan to do some more high voltage / high vacuum stuff... (Bipolar Fusor  )

Thanks
Roman

Btw.: I could imagine the rubber tube is somewhat of an expansion volume in case the oil gets warm and expands?

[Mads Barnkob]

I would guess that it runs around 20-40 kHz, but I think some actually run with variable frequency to determine the output voltage by driving it off resonance, can others confirm this?

Sure, leave the PCB in place and have the mid-point bridge connected.

The filament transformers usually have a very low winding number, so maybe it just leeches off of the HV core? Did I show any of that in the videos? It was a small transformer with some silver wire on if I remember correctly.

You need to protect the diodes from over-load, but if you go full AC by removing them, just stop before you cook the oil

Yeah that was also a discussed use of the rubber tube, for keeping the oil level even at different temperatures and not have it blow out.

[HighVoltageRulezz]

Hello-

OK- it works- sort of.

I used the driver from my other thread with corrected ground(https://highvoltageforum.net/index.php?topic=1150.0) and a bridge consisting of 4 IXYS60N60 IGBTs.
Output is sort of impressive when I simply connect the bridge to the input of the HV tank and supply it with a 47kHz 60V square wave- pretty much the worst case for all the components I guess? It draws around 20A in this mode and the IGBTs get warm pretty fast (obviously I think switching hard?)

Wanting to use it in a SLR way I measured the HV tank inductivity- around 3,7myH. That means I would need a capacity of around 350nF in series to the tank to get a reasonable frequency of around 45kHz? Microwave caps are probably not suited due to the switching frequency? FKP or MKP with a voltage of 1kV?
Would it make sense to use a smaller cap and an other inductivity in series?

Thanks

Btw.: The black tubes in the video are HV resistors to limit the stress on the tanks multiplier

[HighVoltageRulezz]

Hi-

I can not run it in resionance for what ever reason- might try a coil in series to increase the inductivity..

Anyways- I connected a 4myF Capacitor in series to the HV Tank and run it around 45kHz and have the output power I wished for.
I can regulate it by changing the duty cycle and by changing the input voltage with my variac!

Thanks for all the help here!