Yet another OneTesla w/o kit

Non-kit projects based on the public Gen1 designs

Yet another OneTesla w/o kit

Postby Frost273 » Fri Nov 08, 2013 12:28 pm

Good day everyone!

I want to give you a quick overview of mine OneTesla construction.
The task was quite hard as for a lamer, and sometimes it seemed unachievable.

Everything I did was step by step. I collected all the documentations and schematics. Tried to find out of there's anything I won't be able to accomplish.

I began with getting all the components - some were easily bought at the nearest market, some were ordered.
Lot's of time was spent to find out what capacitors should be used or an optical pair of transmitter a receiver.

I didn't waste time while was waiting for components to arrive. I made several other project (now they seem really easy, but they weren't at that time).


Main point I proud of is that I made the circuit board at home. As well as interrupter's one.


As I had some previous experience in programming Atmel microcontrollers the interrupter was fully ready and tested in one week.
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Last edited by Frost273 on Sun Mar 02, 2014 3:22 pm, edited 1 time in total.
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Re: Yet another OneTesla w/o kit

Postby Frost273 » Sat Nov 09, 2013 3:55 am

Later it took lot's of courage to begin winding the secondary. Was scared to spoil pipe and wire.
Nevertheless, the result is slightly more then satisfying ;-)


Soldering all the components on their places:


And finally the result:
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Last edited by Frost273 on Sun Mar 02, 2014 3:23 pm, edited 1 time in total.
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Re: Yet another OneTesla w/o kit

Postby Frost273 » Sat Nov 09, 2013 4:18 am

Some more pictures, I'm way too excited with my progress and I hope you are not tired of my sharings :-)



I should mention that I didn't get it to work from the first time and I fried one of IGBTs due to inattention that heat sink should be isolated from the bridge :oops:

My fuse blew, one of the IGBT's collector and emitter legs were shortened and I lost two MUR460 diodes.

I surfed through the forum for any clues and had found that I'm not the first one with this issue. After I replaced components, bought several thermal silicon pads and mounted heat sink as I should have done it from the beginning everything worked just fine after I switched positions of UCC37322 and UCC37321.


Fine for a short period of time..
I got too excited and turned more then a half of power on interrupter
The sound was getting so amazingly loud
BAM!

I have only one spare FGA60N65SMD left. So I just need to wait for more to arrive.

Thank you for the amazing project!!
:P
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Last edited by Frost273 on Sun Mar 02, 2014 3:25 pm, edited 1 time in total.
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Re: Yet another OneTesla w/o kit

Postby ican » Thu Nov 14, 2013 9:56 am

make sure your interrupter is built to spec for OneTesla... I used a different interrupter that puts out a MUCH brighter light, regardless of its power level and duty cycle, and it will fry IGBTs left and right... We're building another project for that interrupter now, but the interrupter is just as important to get right as the coil itself. =)
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Re: Yet another OneTesla w/o kit

Postby Frost273 » Thu Nov 14, 2013 10:40 am

This is exactly OneTesla interrupter.
Oh wait..
I took it's scheme from archive for 110V tesla.
Because in 220V archive there was non-regulated interrupter, without frequency and power knobs.
Does it matters?
So I should have put another potentiometer (for example 30kOhm), not a 10 kOhm one?
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Re: Yet another OneTesla w/o kit

Postby stegu » Thu Nov 14, 2013 1:01 pm

No, the interrupter is the same for both kits. The only thing that differs between the 220V and the 110V is the arrangement of the MUR460 diodes: four for the 220V version making a full-wave rectifier, two for the 110V version making a voltage doubler.
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Re: Yet another OneTesla w/o kit

Postby loneoceans » Thu Nov 14, 2013 2:42 pm

Well done on the build!

Regarding your blown transistors, if you had built and flashed the interrupter correctly, it should be working fine. However, the most glaring problem that I can see from the photos are the toroid and the primary.

Building a DRSSTC is not as simple as just putting a toroid and wrapping a few turns of wire as the primary coil. You need to make sure that the frequencies are correct - low enough in general to reduce losses in the IGBTs, and within some deviation of each other for best performance.

The IGBTs used should be good to around 300kHz - higher than that and you're pushing them a bit too hard. Your toroid looks very large - depending on your secondary coil, this should lower the secondary frequency significantly. In addition, your primary coil looks narrow, which will increase the frequency too. This creates a large mismatch and seems to me to be the reason why your IGBTs blew (unless of course you have scoped the frequencies and tuned them!)

For DRSSTCs, we usually tune the primary to be slightly lower frequency than the secondary so streamer loading will break the secondary freq in tune. Do you have a scope to find the resonant frequencies?
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Re: Yet another OneTesla w/o kit

Postby Frost273 » Thu Nov 14, 2013 4:27 pm

Mr. loneoceans, I am your fan.

Your site is brilliant so as all of your projects. I was inspired by everything you created, one of the reasons I wanted my one Tesla coil (another reason is that I love big sparks).

I believed I can deal with the secondary only because I was following your "how to"s on poor man's winding rigs ;)

So much awesome you posted a reply, I'm excited as much as I was when my first fuse blew :lol: enough jokes. :)



I guess you're right. The reason of failure is a mistuning. I knew I would have a problems with it, but I couldn't control myself on adding power when it worked. Wanted to push a coil to the limit :) *Achievment complited*


The sizes should be almost right.
Secondary's diameter is 63mm (resistance is 560 Ohm).
And the primary's one is 90mm (well, not 88,9 as planned).

I'm going to add several cascades of protection on the next run (resistor in mains, fast operating fuse, persistent external rectifier, TVSs on IGBTs and larger heat sinks on each bipolar transistor (who know, maybe I'm just too much paranoidal now) >_<

I have access only to an old analog oscilloscopes (1983 year production), don't know if they are able to help.
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Re: Yet another OneTesla w/o kit

Postby Frost273 » Fri Nov 15, 2013 1:38 am

After I bring my oneTesla back to life I'm going to tune it with JavaTC, as you did.

And yes, mine topload is too big - want to cut it in half and make two toploads.
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Re: Yet another OneTesla w/o kit

Postby loneoceans » Fri Nov 15, 2013 3:01 am

Frost273 wrote:After I bring my oneTesla back to life I'm going to tune it with JavaTC, as you did.

And yes, mine topload is too big - want to cut it in half and make two toploads.


Thanks for the comments and I'm glad you enjoy my projects! Hope to have much more detailed writeups on coils soon.

As for JavaTC - super helpful, but you need to make sure you get the measurements right. In my experience, sometimes magnet wire has thicker insulation than meets the eye, so lets say AWG 34 which should equate to 126 turns / inch varies between 120 to 100 turns per inch! The best thing for you to do is to probably use your scope to find the actual resonant frequencies. Your 1980s scope should be more than fine.

Think about doing the resonant matching with the purpose of Increasing your spark length vs preventing your IGBTs from blowing up. Maybe looking at this way more positively should help! :)
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