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What is this HV Multiplier?

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Proud Mary

Thu Oct 28 2010, 06:44PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

EDI do manufacture high voltage rectifiers, but I couldn't find your part numbers on their site:

My instinct is that this device is meant to be potted, or submerged in dielectric oil, and that you will quickly destroy it if you start drawing arcs from it.

If you assume that the capacitor rating is double or triple the peak voltage rating for each stage, you should expect an output of 25kV and more, though you will surely need something more than a dinky little 555 timer to make it run properly.

At no more than a guess, I'd say it was a PSU for a grounded anode analytical X-ray tube - that's what I'd use it for anyway!

radhoo

Thu Oct 28 2010, 06:57PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

Indeed , I'm thinking of xrays as well. Actually I was hoping this was the perfect supply for that, but..not yet.

the module had the output wires cut, and the one that sold it to me was saying that he took it from some larger machine, but no other details. so it's used, and....very clean, so seems like it was running without the oil bath.

Should I manage to make it work properly, I will submerge it in oil, just to insulate it as good as I can and prevent corona (I get some corona atm, but nothing to explain the small discharge)

Proud Mary

Thu Oct 28 2010, 08:16PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

I would be concerned about surficial leakage that leads to carbonized tracking across the board.

No serious designer would expect such a circuit to survive long without potting or oil immersion.

A C&W flashover can often cause domino diode failure down one whole leg of the circuit.

I would suggest you put a protection resistor of appropriate wattage and working voltage in series with the output to limit the current to 1mA.

1n5ane

Thu Oct 28 2010, 08:45PM

Registered Member #3283 Joined: Wed Oct 06 2010, 11:03PM
Location: Toronto, Canada
Posts: 29

Proud Mary wrote ...

No serious designer would expect such a circuit to survive long without potting or oil immersion.

The multiplier sections on Glassman HV supplies are not potted or immersed in oil. They are designed to operate in air without arcing.

I highly suggest that the OP contact glassman and/or spellman, they're very helpful and could potentially give some advice on how to run the board properly.

Proud Mary

Thu Oct 28 2010, 09:20PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

1n5ane wrote ...

Proud Mary wrote ...

No serious designer would expect such a circuit to survive long without potting or oil immersion.

At 40kV or so, the corona forming around the wires at the hot end would quickly start to degrade the board, which has not been designed with any anti-corona devices that one can see. You can almost smell the ozone and hear the hissing just by loooking at it. But who can say? Perhaps electricity behaves differently in your part of the world.

1n5ane

Thu Oct 28 2010, 10:01PM

Registered Member #3283 Joined: Wed Oct 06 2010, 11:03PM
Location: Toronto, Canada
Posts: 29

I don't question how or if it works; Glassman obviously put some thought into designing it, otherwise they wouldn't still be in business...

Here is an example:

As you may notice, there is no potting or oil encapsulating the HV multiplier section.

quicksilver

Thu Oct 28 2010, 10:13PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

It could be a plasma display power supply. I found one surplus:

Proud Mary

Thu Oct 28 2010, 10:20PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Radhoo's device doesn't have the interstage anti-leakage slots cut in the board that feature in your glassman example, but perhaps you are right. I have no idea.

radhoo

Fri Oct 29 2010, 06:56AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

There are too many components to justify just 25kv . I assume they built more than the one module I have, so the components could have been a little pricey, judging that there are cheaper alternatives like one single bigger flyback with or without a simple cascade.

Regarding what this is, one clue is that the output is negative. I'm still waiting for more details from the person I got it from.

radhoo

Fri Oct 29 2010, 07:01AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

Just looking at 1n5ane's link with the Glassman multiplier:

Picture:

It appears there are Gas discharge tubes for some overvolting protection purpose. My board also has Transient voltage suppression diodes (the black components in the picture)

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