High Voltage Forum
Tesla coils => Solid State Tesla Coils (SSTC) => Topic started by: Weston on June 18, 2020, 10:36:40 AM
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I have been watching a bit more youtube videos due to lockdown and I just wanted to draw attention to a recent SSTC construction video series by a youtuber that does a lot of power electronics related youtube videos, DiodeGoneWild.
He is what I would call a "professional russian" and his equipment and techniques are pretty bare bones, to the point where it makes me feel guilty for having a nice oscilloscope. He covers tesla coil / power electronics theory really well and shows you can do a lot with some pretty basic equipment.
I would say these videos are the best SSTC introduction / tutorial on the on the internet right now. There are a number of videos in the series, here is a link to the most immediately gratifying video where he gets his first sparks (check out that topload!)
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He also has a web site - http://danyk.cz/index_en.html (http://danyk.cz/index_en.html) with tons of HV and general electronics stuff.
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His videos on the Tesla coil series are just amazing !! He got pretty big Sparks without the feedback and uses the most basic ir2153 chip to get the job done , no gdt stuff but yeah that offers no isolation also. But he no interrupter , and is using the mains half cycle power to basically regulate the power going to the chip to turn it on or off. But I have question from this , is it right to just apply / cut power to the chip ? Wont that cause any malfunctioning etc
By the way his videos on the power supply , smps is also pretty interesting. He explains all the " black magic " involved in the startup etc really well
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His video series motivated me to actually finish my first SSTC as well.
I started it about 2 yeras ago but the driver I initially wanted to use didn't work and blew up so I never came around to finish it.
(I tried to simply use a PWM driver with around 28v primary voltage to drive the coil.)
I built my new driver basically exactely as DiodeGoneWild's with a few minor changes to work for my coil and with the components I had lying around.
So I definately don't take credit for it in any way. :)
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I also went ahead and inserted a "Angstwiderstand", meaning fear resistor in the high voltage path to protect my IGBTs, since I killed a few of them in the past days.
The coil resonates at around 180kHz, but I totally forgot the windings. :-[
It worked pretty well after a few failed attempts.
And I'm very happy with my first sparks.
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About the problem of the snubber resistors heating up, would something like this be a valid replacement?
https://www.mouser.de/ProductDetail/Johanson-Dielectrics/RHXH2N005R0F4?qs=ofF%252BRbqKDcbsxZhLL6ooFg%3D%3D
https://www.mouser.de/ProductDetail/Johanson-Dielectrics/RHXH3N005R0F4?qs=ofF%252BRbqKDcYl15M3LLrEbQ%3D%3D
These are generally pretty good for RF circuits, so I guess they should work here as well?
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I've seen a couple other coilers use big low inductance decoupling capacitors on the supply rail across their upper and lower fets, but right at the pins of the devices to reduce the spiking and ease the snubber resistor heating.
https://www.easternvoltageresearch.com/content/datasheets/book_preview01.pdf (https://www.easternvoltageresearch.com/content/datasheets/book_preview01.pdf)
On page 9 under "Full-Bridge Top Assembly".
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Interesting, thank you, I might give this a try.
The attached pdf seems like a good reading for someone like me who hasn't a lot of experience with SSTCs. :)
I guess the value should be chosen, so that the impedance of the capacitor is reasonably small at the resonant frequency, since they are used as bypass capacitors?
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I'm not 100% sure but I recall people warning about the bridge capacitors resonating with the DC rail if not careful. I just used what was in my parts box until I saw waveform improvements.
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As John said: "I'm not 100% sure but I recall people warning about the bridge capacitors resonating with the DC rail if not careful."
Yes, it appears to happen occasionally, as in this thread:
https://highvoltageforum.net/index.php?topic=1058.msg8182;topicseen#new
Finally figured that out in my reply #36. In this case the local VBus film capacitors and inductance back to bulk VBus capacitors resonates at 2X the coil primary frequency. VBus current ripple is mostly at 2X primary frequency (and harmonics of that), as VBus current is the full-wave-rectified version of primary current.