Oh, some people had actually replied under this topic.
I checked it maybe 4 days after posting and there was nothing – thought people were like meh.

Anyway, I really appreciate that there's some interest to my work – you'll really like my other boards, I'll write about them a bit later.

So, the question-answering time!

I really really like how all of the control i/o pins are all along the same edge at the back end, and the fiber input and indicator LEDs are on the same side, facing you. Looks like it was really well thought-out. Great job!

Actually, I had plenty of time perfecting this design – first ever version v0.1 of SimpleDriver emerged into existence long back in 2014 and looked like this. https://i.imgur.com/E3GcNpr.jpg
Over the next years there were also v1.0, v2.0, v2.1, v2.2, and now it's v2.3.
http://tqfp.org/forum/download/file.php?id=1347&mode=view (v2.0 back from 2015)
http://tqfp.org/forum/download/file.php?id=1943&mode=view (v2.2 from 2017)
Most likely there'll be new versions in the future.

Hi Eugene and thank you for sharing your driver and its incredible detailed documentation, that is high class example of how good documentation can be on a product without giving it away when you still have the software secret.

95$ is quite steep compared to some of the Chinese manufacturers that comes out everywhere by now and which are another reason why I stopped trying to sell a simple cheap driver myself, as I got no chance to sell anything with a price on a simple driver being higher than a more advanced Chinese one. However you have documentation with yours, that is seldom the case with the Chinese, at-least not in English.

There's been quite a huge battle over proprietary VS open-source hardware design philosophies.
It seems like OSH had won the hearts of common people, but my personal observations/experience tell a different story – in almost all cases OSH devs have very little motivation to work on their products.
I mean, these are rarely being developed past the point of early alpha, there are barely any documentation, and practically no user support...
Which isn't surprising, most of these projects are made not as something useful for other people, but usually to get a little fame on resources like Hackaday. After that the project usually gets completely abandoned.

In contrast, designing real commercial products can keep you motivated for years even if it's not some bestseller – you'll be happy to provide long-term design-support in new features and reliability improvements, write articles, and support every user who's currently using your design. All you need is knowing that there are actual people using your stuff, and that it pays for further work on imroving it.
Not sure how you guys, but I have a special R&D bank account that pays for all the prototype boards, parts, deliberately exploded units, and of course pizza.

On chinese manufacturers – I'm pretty sure these aren't a big threat for us westerners, at least yet. Of course, casual buyer will purchase a driver for $45 just because "woot! It's so cheap!", but I haven't seen these even having a basic phase-lead.
Those who try building Tesla coils for professional use will probably play with these for little, burn up a few IGBT bricks and then get a proper driver like UD2.7/UD3/UD+, or SD.

On my price being steep – earlier SDs had the price of only $75, but it wasn't easy providing further support to every new user. I made it $95 on v2.3 with new features like alternating shift and pulse-skip. At that moment I hanged with dudes from France and Switzerland and they said that my driver was dirt cheap cause cheapest UD v2.7 clones costed there $135.

On the software not being open-source – that's basically to avoid easy production of clones. Believe it or not, but I personally know a dude who makes whole batches of UD v2.7 clones for direct purpose of retail.
Those with at least basic knowledge of HDL programming will have no problems recreating the driver by relying on operation principles provided in the article.

My goal is to implement freewheeling, phase-shift PWM with alternating hard-switching between the half-bridges and the ramp generation completely without analog circuits. At the moment the whole gate drive logic is implemented with a state machine. The ramp will be generated either directly in VHDL or within a NIOS soft core.
Unfortunately my progress is slow as I build a matching QCW tesla coil in parallel.

Is your SimpleDriver used during this performance?

Actually, my earlier driver was completely digital – FPGA based. Required around 450 MHz for digital phase-lead. http://tqfp.org/uploads/images/00/00/01/2013/02/21/ec0a74.jpg
It had USB interface and had to be configured from PC which also required writing and supporting software for Windows.
While developing a new version... Well, I ran into the same problem – the design became too complex and progress was super-slow.
Eventually, I just designed a new one that relied on analog-digital technology – it worked.

Should be enough for now, there'a already a whole essay here. Will be happy to answer more questions though – feel free to ask. Also, bluetooth poly-interrupter topic is coming.

Greeting and salutations!

I've been into coiling for quite some time, but my work is mostly known in a local region of Ukraine/Belarus/Russia and is very obscure overseas.
I think I'll try making articles in english and start demonstrating my stuff here on HV forum – I hope you'll like my work.

Let's start with the driver board, it's called a SimpleDriver and allows users to build QCW coils without bulky buck-converter – relying on phase-shifting technology.
Power output of the full-bridge is controlled solely by an SD board, which allows making QCWs simple and very compact.

Actually I made a huge super-detailed article about it, which also explains the thing's operation principles. Check it out!
http://tqfp.org/simple-tesla/simpledriver-v23-in-english.html#!prettyPhoto

And just to catch your attention – a couple photos!





P.S. Let me know if you liked the article, I got much more things, like wireless 6-note poly. interrupter that can be controlled from a phone.
http://simpletesla.ru/wp-content/uploads/2017/08/6006b6.png

That method's super popular in my country, called "laser ironing".
Personally though – I prefer using lithography, a.k.a. photoresist method since it gives better quality and doesn't require heating up a huge iron...
But the method definitely has it's place since it doesn't require any unusual chemicals.
I know a few tips regarding the topic, maybe somebody will find them useful.

1. Softening up the paper with regular water can take some time, and still – peeling the remaining paper off can damage the traces.
Instead of water I usually used powerful caustic soda solution – it's super aggressive against cellulose and quickly dissolves it, especially when the solution is heated up.
For heating the microwave oven is really handy to use, just don't do it with the PCB floating in the liquid.
After 1-2 minutes in a caustic bath most of the paper's gone, and the remaining one can be washed off under a water faucet.
That's useful not really for saving time, but mostly if you're trying to make PCB with small details, like 0.3 mm traces and TQFP chips – undissolved paper bridges between traces mess up the etching process.
However, that's definitely the limit of this technology – for good precision and chance of success photoresist works much better.

2. In theory – it's possible to make PCBs without the huge heated iron, using only acetone and a towel.
Just water-up the PCB and print-out with little acetone, then push them against each other with force using a soft towel, after 5 seconds release and peal off the paper piece.
Toner will be transferred to the PCB surface. What's cool about this method is that it can be used with plastic or heatsinks as well – that either can be melted with ironing, or radiate too much heat and the ironing method works poorly.
This method isn't very reliable, but it works – anyone can just try it out. Here it's mostly used not for PCB manufacturing, but for making writings/logos on plastic cases or keyboard keys.
Of course, after being transferred to plastic – toner should be covered with some lacquer, otherwise it'll peel off fairly quickly.

Hope some of it was useful, cheers.

Hail fellows, I'm new here.

Well, little about myself – I'm a 24 y.o. dude, living in Ukraine and doing electronics for hobby. Got special passion for HV stuff.
Already got plenty of cool projects, bot they're mostly known only in my region, I rarely appear on foreign forums.

Well, I hope you'll be interested, I'll tell about some of them in the topics.
-Eugene.