Dawncap dedicated resonant capacitors

[L_Mangold]

Hello, my name is Stuart and I am new to this forum. I’ve been lurking for a long time on 4hv and more recently here, and I’ve learned a tremendous portion of what I know from two wonderful references: Kaizerpowerelectronics.dk and loneoceans.com/labs. My field of expertise is biochemistry, not electrical engineering, but learning electronics has become a passion over the last 2 years or so. I’ve made a few SSTCs over the last year, and I’m currently working on my first DRSSTC. I’m extremely grateful for everyone who has shared their knowledge and experience on the subject, and I’ll try my best to contribute as well in a meaningful way.

My only question today is if anyone has any experience using Dawncap capacitors as their primary tank capacitor(s), and if so, how successful was this design?
http://www.dawn-cap.cn/index.php/Index/index/lang/en.html

These are abundant on eBay and aliexpress, so I’m curious if anyone here has any opinion on them, vs the standard CDE942 caps most designs use.

[Mads Barnkob]

Hi and welcome to HVF!

I have also had an eye on Dawncaps as they seem to be the cheapest alternative if looking at new capacitors.

I looked at the DER and DMS series, apart from the horrific spelling the capacitors look good on paper.

DMS: http://www.dawn-cap.cn/upload/201611/DAWNCAP-DMS%20%202015.pdf seems to be a direct competitor to the CDE 942C series but there is missing quite a few specifications, so be sure to calculate something like the ESR before buying, if you need help to do that, check the math at the bottom of the page here: http://kaizerpowerelectronics.dk/theory/good-mmc-capacitors/

DER: http://www.dawn-cap.cn/upload/201812/DAWNCAP-DER.pdf for a snubber capacitor it still has a rather high ESR value for 85 kHz, so be sure to check that with your resonant frequency, else the capacitance, voltage and rms current ratings are great for a DRSSTC MMC.

You can be the first to use, test and review them for a Tesla coil

[L_Mangold]

Thank you so much for your input! I am specifically using this capacitor: https://www.ebay.com/itm/DTR-0-18UF-2500V-AC-60A-4000V-DC-high-pressure-Resonant-capacitor-G1031-XH-yh/182178680534?hash=item2a6ab20ed6:g:LGoAAOSwzJ5XaLxM
I can't find a datasheet in english, so I'm hoping that the 60A rating is the RMS current rating.

The coil I'm working on is small to midsized, roughly 115 khz unloaded (though I don't have the exact measurements right now and I'm making a new topload), 9cm diameter, with roughly 1600 or so turns with 34AWG . I have two IXGN60N60C2D1's with certificates from a reputable dealer after I learned the hard way that most of them from eBay are, predictably, not genuine. I decided, however, to use a CM200DY-24H for a half bridge w/ voltage doubler. I'm only experimenting right now, and I have a nice variety of different inductors for tuning phase lead, so even though it's overkill at the moment I like having the breathing room until I can optimize everything. My budget is limited (as is my knowledge and experience), and the IXS SOT-227's were a bit too pricey to be experimenting with at the moment

I'll post some pictures and measurements either tonight or tomorrow, and I'll be happy to let everyone know how this capacitor performs! If things go well, I'll likely get three more for an MMC of two parallel rows of two in series for a rating of 0.18uf, 5kVAC (8kVDC), 120Arms.