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Posted (edited)

I’ve replaced 120R and optocoupler circuit with a DN2540 circuit. In LTspice it seems to work.

Circuit.thumb.jpg.ad59882231959990a5a12180bedf9d57.jpg

If input offset is +100V then I get a current in the Circlotron of 850 mA with the optocoupler and 75 W at 120R resistor and 750 W at the MosFet. With DN2540 the current stays at 25 mA and DN2540 will take some 2.7 W and hopefully nothing will blow. This is of course in theory and what will happen in real life is a completely different story.

 

Edited by JoaMat
  • Like 3
Posted (edited)
5 hours ago, JoaMat said:

I’ve replaced 120R and optocoupler circuit with a DN2540 circuit. In LTspice it seems to work.

Circuit.thumb.jpg.ad59882231959990a5a12180bedf9d57.jpg

If input offset is +100V then I get a current in the Circlotron of 850 mA with the optocoupler and 75 W at 120R resistor and 750 W at the MosFet. With DN2540 the current stays at 25 mA and DN2540 will take some 2.7 W and hopefully nothing will blow. This is of course in theory and what will happen in real life is a completely different story.

 

The TO220 version of the DN2540 is rated at 15 watts dissipation, but I assume that is with adequate heat-sinking.  I would bet that the bare TO220 without heatsink will only tolerate a couple watts, so I assume you are mounting all devices on a heatsink.

Edited by JimL
Posted

My idea with DN2540 instead of “120R resistor” is that you might have better control of the current in the Circlotron. Under normal condition you probably don’t need heat sink with DN2540. 100 V offset should never happen with a good driver but that is in a perfect world. Anyhow, worst case is an offset of +450 V  and then the DN2540 is reaching or exceeding its maximum both voltage and power.

But I could be all wrong about this.:(

Posted

Below is from my kitchen today.

_MG_1605.thumb.JPG.c246a940dc8a3668616ac7f2e902e4cd.JPG

I had to test if the DN2540 would do. 25 mA on the meter and voltage, from an old KGSSHV supply, is 887 volts. Only one half of Circlotron and the current seems to stable enough. Might be continued if I don’t break arms and legs during coming week down hill skiing.

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  • 1 year later...
  • 10 months later...
Posted

Since I've got the Carbon up and running for a couple of months, I'd like to bring it up to another level and have been thinking of the Circlotron for a while.

I wonder if there's any interest in the board sets? These would be 2mm/3oz with latest files posted by Kevin. I could also provide Nippon-Chemicon 470uf 550v caps.

I'm not using any off-the-shelf chassis though, it would be built from scratch, but I guess a standard 5U one would work fine. Probably I will do like EUVL did with his F5X chassis, with both output and driver boards stacked on both sides of a thick teflon sheet. Same thing with the single 900v PSU.

These are the boards that I'm thinking of ordering. Both Driver and Output are v2, PSU is v3. The GRHV is a dual version, not singles because I plan to mount the transistors on the bottom plate.

Feel free to PM me if you have any interest. This is my first time doing this so any if there is any inconvenience, please pardon me.

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