Switch Mode HV CCPS to drive ferrite core HV transformer.

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Doug Coulter
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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Doug Coulter »

I'm good on the connector, I probably have 20 laying around, I just have to go look. I had to do errands this afternoon that prevented that, but tomorrow is another day....

This is very much like the spellman PTV series, you need about the same external stuff to make it sing, it's not a big deal at all, they wanted it to be easy to put into other gear.

And as this was designed to be shorted out in normal use (when the laser goes) it should be really nifty, though a bit high powered for most of us. My 2kw Spellman is utter overkill, for example, enough to vaporize things easily that you didn't want to have go poof.

At first, I'm going to use it as the main DC for my HV video amplifier for pulse mode tests...for which it's perfect as is. I had a supply for that, but all that old iron is pretty hard to lift compared to this thing.
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Carl Willis
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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Carl Willis »

Hi Lutz,

I DO NOT have a manual (the results of getting a bargain on the PSU I suppose), but I did find a description of the DB-15 pinout via The Google:

http://sci.tech-archive.net/Archive/sci ... 00027.html

It's too bad we can't get an official schematic. It would certainly help with the reverse engineering of the circuit. The control board is a little hard to trace because it is multi-layer. All of the logic ICs and the PWM chip are standard, common parts and it should not be terribly hard to find out what the control philosophy is, traces notwithstanding. I'll put up a schematic of the output board and its J1 jack tonight, and maybe try to comprehend some of the logic on the main board as well.

-Carl
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Doug Coulter
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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Doug Coulter »

Carl,
Unless you have some application in mind I don't know about, I don't think we actually need to reverse engineer the whole thing (from my pov, that's more work than designing it again). The HV board generates voltage and current sense signals in the most obvious possible manner -- all we would have to do it dupe that stuff appropriately to match any changes in the transformer or HV multiplier stuff.

It's just a resistive volt divider for the voltage, and in mine 3 3 ohm R's in parallel on the ground side to sense current.

Very straight ahead. The rest I'd just treat as a black box, myself.

The design is quite similar to that seen in many Spellman supplies, BTW.

The manual indicates that this same design is used up to fusor voltages by just changing the xfrmr/HV rectifier board module...so we can do that too.

I do have the manual that gives the pinouts for the db 15, and all you do is close an interlock with a short, and put in a voltage (0-5v) to tell it what output voltage to make. It reports actual voltage back on one pin as 0-5vdc, and there are a few status/fault led drivers too. There is a 12v reference you can use with a pot and a resistor (or a fancier regulator) to generate the supply voltage command.

It's already designed to be hooked across a capacitor that gets shorted (by a flashtube) at some hertz, the test document I have says they use a 75 uF cap charged to full volts at 13 hz and cycled.
So it will take a lot of abuse. There appears to be no provision for changing the current limit easily, but that's not a big one to me -- it would be possible in a number of ways if needed just by faking the current sense output levels. It does have a function that if you tell it to put out voltage, and it takes "too long" it will give up and shut off (which sets one of those fault indicators).

Should be a piece of cake to change the output stuff but send similar signals back for current and voltage so the other stuff never knows you changed anything at all.

I wouldn't try changing frequency much (which would be easy at the 3525 chip) because there's more than one transformer in the drive chain, which means there will be limits due to that....but it's already at a good frequency, mine states it's 34 khz.
(I did get the manuals, and the test setup and report).

No schematic, but no need for all that stuff, really.
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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Carl Willis »

I attached the schematic for the power supply board. Colored wires are those on the J1 jack. NOT SHOWN is the interlock short between the white and black wires.

The transformer has a 1:4 step-up ratio (full primary to each of the two secondaries) and very little leakage inductance; it is close to ideal. For comparison the Spellman DXR3000 transformer is a ~1:50 unit with primary magnetizing inductance of 280 microH, my measurement; 317, Jon Rosenstiel's). I think this inverter would probably drive the DXR3000 transformer very nicely. I also have a transformer from an ion implanter with even higher turns ratio that will probably make a totally sick discharge when supplied from this inverter.

The HV divider and current sense resistors indicate that the high voltage feedback signal is ~0-5V and the current sense is simply 1V/A.

-Carl
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Mike Beauford
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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Mike Beauford »

I just picked one of these up. I'm going to dive into it in a couple of days when it shows up. I'll let you know what I find.

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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Carl Willis »

I feel like I got my money's worth in this Kaiser supply.

Tonight I hooked its half-bridge inverter up to a variety of high-frequency transformers (in place of the original transformer) after bypassing the feedback and interlock logic. I also installed a separate off-line doubler for the 24-V supply and put a Variac in the AC feed to the main inverter for better control while testing. Operating frequency was 31.6 kHz.

The inverter behaved very well with transformers that didn't saturate and had a magnetizing inductance similar to or less than the original transformer (0.4 mH). These included the transformers in high-frequency NSTs ("gas tube power supplies"), with magnetizing inductance of 0.21 mH; and the large Spellman DXR3000 transformer (0.28 mH) shown in the photo. A large transformer from an Advance Hivolt implanter supply with magnetizing inductance of 90 mH and probably designed for 5 kHz drive caused the large power resistors on the inverter board to get hot.

I took the below photo while peeling a thick arc out of the Spellman transformer. The inverter heatsink stays cool during this kind of treatment, as do all the parts my finger can reach. The flimsy clip leads to the transformer primary are a weak link, getting quite hot.

Now to hook up a multiplier and exploit the feedback controls in this supply to get a regulated output. I'll bet the eBay glut of these Kaiser supplies for $15-$25 is still going strong, and they seem to be well worth the money in useful components for high-power HV stack drivers.

-Carl
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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Pablo Llaguno »

Sadly, these supplies now cost hundreds of dollars on eBay...
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Re: Switch Mode HV CCPS to drive ferrite core HV transformer.

Post by Richard Hull »

Yes, 11 years have past since Carl's post. The passage of time does change prices.

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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