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4hv.org :: Forums :: Projects
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Small Bi-polar SSTC

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Dr. Spark
Tue Nov 21 2006, 04:25AM Print View
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day great coilers,

I am now madly in love with solid state Bi_Polar coils. How little power they take and how fast they can respond is incredible ! Demo Lady Red for DC Cox this weekend and he was grinning big time.

I have 1.2 months left before the W.W.T. so thought I could squeeze one more project in for demo at the Thon. A small SSTC Bi-Polar with a surprise feature. So pics tonight are the starting project, coil will be all plexy with UV LED’s. Will update with pics but this will be the fastest built coil I have done in many, many years….. Have a goal to meet, so off the computer and back in the garage…

Cheers,
Ch_r






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Dr. Spark
Mon Nov 27 2006, 03:36PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

Busy turkey weekend!

Bi-polar SSTC is starting to take shape.

Used 31 AWG on the secondary, Now working on bridge…

Cheers,
Ch_r






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Dr. Spark
Wed Dec 06 2006, 01:06AM
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Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

Coil is coming along nicely; secondary is done, bridge is done, now working on logic to drive bridge. 50 amp 500 volt MOSFETs is an overkill, but will let me push this little creature into a black hole, he he!


Cheers,
Ch_r






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Dr. Spark
Fri Dec 08 2006, 02:41AM
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Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

Starting to use ¾ inch plexy and sure gives it a nice appearance on the edges….
Will transfer the UV LED’s light very well. Back in garage I go!


Cheers,
Ch_r








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Dr. Spark
Wed Dec 20 2006, 10:00PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

Starting to look like her sister (Lady Red) but a bit easier to bring over to friends for demo after dinner….and no RF ground required……

Cheers,
Ch_r








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Dr. Spark
Mon Jan 08 2007, 03:34AM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

Looks like I have the coil ready for the thon in two weeks. Shhhhhhhh, I blew it up the first time….but a new driver board, fine tweaking of decoupling and more turns on the primary and the coil is solid. Ran a full Music CD and no heating of any component..the little coil just sings!

Another low powered Bi-Polar at 3 amps at 85 volts into bridge…no voltage doubler…

Now I want to make a big singing BI-Polar, he he……!



Video @



Cheers,

Ch_r





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Marko
Mon Feb 12 2007, 08:52PM
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3144
It's simply so perfect.. I had little to say about it.

Audiomodulation by frequency shifting seems hard on FET's since they go out of soft switching. This can ofcourse be solved with external diodes.

If you want to experiment (you would be the very first to do that on such bi coil) you could try to use a modulated buck/buck/boost converter/class D amp to modulate the supply rails directly.. I guess only imagination limits you there.
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Avalanche
Mon Feb 12 2007, 09:12PM
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Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 811
wrote ...
you could try to use a modulated buck/buck/boost converter/class D amp to modulate the supply rails directly.. I guess only imagination limits you there.


Definitely the way forward for serious sstc audio modulation - a few months ago when I was playing around with making my own inverter it turned into an audio modulated power supply for that purpose. I wasn't going to mention anything about it until I got it beyond the breadboard and to the 'impressive' stage, but that never happened. I think it was more impressive with a function generator hooked up, to produce insanely loud triangle waves. Maybe one day I'll get it running again and revive the project thread!
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ragnar
Tue Feb 13 2007, 01:24AM
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You wouldn't be the first to modulate the rails -- even for my really old audio-modulated current-fed push/pull flyback mess, I used a FET, source-follower, for audio modulation. I also used it on my very first ever coil, but quickly learned that I didn't have any heatsinks big enough.

The great thing about a pulse-width modulator supply is it can serve two purposes; A) to step down the voltage from the mains, if you're running a resonant switching topology (e.g. class-E amplifier, where voltage across the MOSFET is equal to pi * Vin, MINIMUM) and B) of course, proper rail modulation for audio.

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Marko
Tue Feb 13 2007, 12:34PM
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Location: Zadar, Croatia
Posts: 3144
you wouldn't be the first to modulate the rails


I didn't say that, but he would be the first to do it on really big coil (afaik, waverider also sucessfully modulated his 6Mhz coil that way).

I'm not sure wich topology would be best, maybe a buck/boost since it can also give higher output voltage (if more power is wanted).

I would just modulate the comaprator input of a PWM IC, without any feedback and use small smoothing capacitor.

Big input filter cap would worsen the PF, if anyone actually cares about it...
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Dr. Spark
Tue Feb 13 2007, 05:17PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

I have been tweaking the tuning and found this really helps sound quality big time! I will make another video tonight with new song and publish on youtube, but man it sure sounds xtal clear now. The modulating of Power supply sounds interesting indeed, how is sound quality? I guess I should build a coil using this and compare findings.

This little coil is really getting a lot of fun demo to friends and family in the last month. Now I want to build a big singing Bi-polar, will need a lot of fans and big heat sinks. Only issue is the sound is so clear, all think I am using a speaker somewhere and that sound cannot be coming from the spark. Even at the Thon I was told that this is a joke, there is no way a spark can be so clear on music……………..I love it. Can not wait to make a 120db singing coil, he he!

Maybe time to roll a 75 gal tank of LN2 from work to my garage, he he.

Rgs,
Ch_r
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Dr. Spark
Wed Nov 07 2007, 01:36AM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
OK, what is he up to now?

Hmmmmmmmmmmmmmm


Cheers,
Ch


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Dr. Spark
Sat Nov 10 2007, 06:48PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

Putting an audio amp a few inches below a primary is not a fun thing, had to do a few things to keep RF out, butttttttt now she is singing happy.

Starting to build in modules that stack on top of each other.

Easy to transport, requires little foot print and can squeeze more coils in garage.

Working on the control panel now as this module will sit under cassette deck with wheels. Each module will have a Molex connector.

Cheers,
ch












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Spedy
Sat Nov 10 2007, 08:16PM
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Joined: Wed Aug 22 2007, 12:39AM
Location: Stockton, CA
Posts: 134
That looks great. It's hard to believe its a TC making that noise. Great job!
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Dr. Spark
Mon Nov 26 2007, 06:09AM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
A project is done (1 year and 5 days)…..hmmmm….nice indeed.

Control panel had some room so added a 12 watt 5 inch subwoofer and amp.

I like the modular stack, can still add a CD player.

Fine tuning the coil as reduce side loads to 6 inch.

Ran for 90- mins (both sides of tape) with no issues.

Cheers,
Ch

P.S. here is a video @

















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Tom540
Mon Nov 26 2007, 07:21AM
Banned on 3/17/2009.
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Awesome! Except one thing...... THAT SONG!!! !
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Dr. Spark
Mon Nov 26 2007, 03:55PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Tom540 wrote ...

Awesome! Except one thing...... THAT SONG!!! !


Well it is hard to pick music that all will be happy with, as my dad wants me to put Perry Como on.

This coil will be fun at the Thon as can put 90 minute tape in and let play in corner for back ground tunes.

The modular stacking turned out so well that will build all coils in future like this. Easy to roll around, pack and move making a great way to store and use coils.

I tried something new as started with blue LED’s at top of coil and ended up with Red LEDs at bottom. Kind of give a different effect.

Cheers,
ch

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Tom540
Mon Nov 26 2007, 04:14PM
Banned on 3/17/2009.
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Maybe something that will push its limits. Techno or trance. Damn I want one now. hehe. I would store that one in the house for sure.
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Marko
Mon Nov 26 2007, 08:37PM
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3144
Looking around all the time now... I've just never actually seen an audio modulated coil doing big, I mean really big singing sparks. Everyone seems not to be able to do more than few cm sparks. I wonder if anyone will manage to break 1 foot mark... but I think not with the topology that is currently used.

The main problem apparently isn't hard switching, but the massive amount of reactive current you have in your primary - and exceeding your mosfet rating is to easy.


I was thinking about the hypothetical modluateable power converter (class D amp) which you could use to drive the coil in tune without need for FM modulation or hard switching.

Still, that would mean large piece of ferrite to process all the power, and still your SSTC switches would be very stressed.

Since there is no way you could get without a hard switched converter anyway, I thought there could be simpler way around:

- Some LARGE ferrite. Like this.


You build a normal coil, and use FM or PWM audio modulation; but, instead of your primary coil, you wind a step-up transformer onto the core and run it into magnifier mode, through base feed.

You will be hard switching, but current stress on your switches should be many times smaller and allow you to give out some real audio-modulated output.

Those inverter welders work well with hard switching and your circuit would now be nothing but one such an inverter with a resonator stuck onto end. You could get rid of all the control loop problems associated with class D amps.

I know it's a huge project, but you are definitely by far biggest candidate for something like that! Getting things like large ferrites and mosfets isn't a problem for you, so it depends on how much you like big audiomodulated sparks!


Awesome! Except one thing...... THAT SONG!!! !


Well... Where is that chrunching sound coming from?

Chris:
To show the coil off.. I wondered if you could just play something very well known, neutral, classical and liked-by-all?

Maybe something like this?

Or you just wouldn't try to play anything classical at all?

Marko
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Dr. Spark
Mon Nov 26 2007, 09:31PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Yes, I do have a big Audio coil on the Horizon. I wanted to understand what it requires to ensure audio is clear, so played with this one for a year or so.

Hard switching these FET’s really is no big deal; just ensure you can get the heat out of the die.

The issues I had was the gate drivers. I ended up having use eight drivers to keep the signal from clipping. Big focus on next coil is trying to use newer FETs with lower gate drive requirements. Also try putting an Equalizer, Subwoofer Amp and cassette player under a coil, talk about RF issues, wheeeeeeeeeeeeeeeeeeeeee!

When I use to demo the coil, had a variac on the floor, cassette player across the room and the coil in the middle of the room. What a pain in the butt; however, now just roll coil out and plug in. No RF ground, no extra wires…..just drop in music and turn up variac (Volume).

Finding that the easier to setup, the more demos run.

Cheers,
Ch


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Marko
Mon Nov 26 2007, 09:40PM
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3144
Yes, I do have a big Audio coil on the Horizon. I wanted to understand what it requires to ensure audio is clear, so played with this one for a year or so.

Hard switching these FET’s really is no big deal; just ensure you can get the heat out of the die.

The issues I had was the gate drivers. I ended up having use eight drivers to keep the signal from clipping. Big focus on next coil is trying to use newer FETs with lower gate drive requirements. Also try putting an Equalizer, Subwoofer Amp and cassette player under a coil, talk about RF issues, wheeeeeeeeeeeeeeeeeeeeee!



But we want 1-2 foot audiomodulated arcs, not these tiny ones, right?

Hard switching is not exactly a killer alone, massive reactive current (because of poor primary to secondary coupling) is a killer. You probably figured out to what can you push those ''too small'' 50 amp mosfets.

I'd really want to see a big-sparking audiomodulated SSTC (not DRSSTC!) - that's one of things that need to be acheived yet.


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Dr. Spark
Mon Nov 26 2007, 10:40PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Marko wrote ...

But we want 1-2 foot audiomodulated arcs, not these tiny ones, right?

I'd really want to see a big-sparking audiomodulated SSTC (not DRSSTC!) - that's one of things that need to be acheived yet.




A SSTC audio modulated magnifier…with sparks over two feet. O.K. the project will start in Jan. Will have to dig for some big FET’s.

Of course it will have to wait till Quad VTTC and MARX is done, but plan on completing those by end of this December.


Wish I could run under LN2 however, wonder how I can get one of these 50 gal tanks home form work. That will keep them cool and low resistance at -50c.

Cheers,
Ch


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Steve Ward
Mon Nov 26 2007, 11:53PM
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Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1007
2 foot of CW spark needs like 5kVA+, its surely no easy feat.

Ive developed a high quality class D amp for a semester project, and with that experience id say its certainly possible to use a class D front end on a SSTC, but the real question is why? The SSTC itself closely resembles a "clocked" class-D amp, so i dont see the point in adding another switching stage. From what ive learned with my self-oscillating class D design, i wonder if a similar operation could be implemented with self-oscillating SSTCs to modulate them.
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Dr. Spark
Tue Nov 27 2007, 01:55AM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Steve Ward wrote ...

2 foot of CW spark needs like 5kVA+, its surely no easy feat.



5kVA and an achievement, hmmmmmmmmmm please send contributions by paypal to my email account, hee hee!

Still think a SSTC magy with primary and first secondary in oil housed by plexy with some big fat FETs at 240 volts @ 50 amps on doubler would make some really nice CW audio……………………..! Of course the oil is lit up with LED’s like my Quad MOT’s @ .

Cheers,
Ch


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Dalus
Tue Nov 27 2007, 12:50PM
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Joined: Wed Apr 11 2007, 09:09PM
Location: The Netherlands, Herkenbosch
Posts: 512
Steve Ward wrote ...

2 foot of CW spark needs like 5kVA+, its surely no easy feat.

Ive developed a high quality class D amp for a semester project, and with that experience id say its certainly possible to use a class D front end on a SSTC, but the real question is why? The SSTC itself closely resembles a "clocked" class-D amp, so i dont see the point in adding another switching stage. From what ive learned with my self-oscillating class D design, i wonder if a similar operation could be implemented with self-oscillating SSTCs to modulate them.


Guess what I was planning to build next month, a self oscillating class-D teslacoil.
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Marko
Tue Nov 27 2007, 01:52PM
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Posts: 3144
The SSTC itself closely resembles a "clocked" class-D amp, so i dont see the point in adding another switching stage. From what ive learned with my self-oscillating class D design, i wonder if a similar operation could be implemented with self-oscillating SSTCs to modulate them.


Steve, and that *was* the point of my post!

5kVA and an achievement, hmmmmmmmmmm please send contributions by paypal to my email account, hee hee!

Still think a SSTC magy with primary and first secondary in oil housed by plexy with some big fat FETs at 240 volts @ 50 amps on doubler would make some really nice CW audio……………………..! Of course the oil is lit up with LED’s like my Quad MOT’s @ .

Cheers,
Ch


Chris, I don't think you'll achieve anything with air-cored transformer magnifier, simply because your coupling gets too low and magnetizing current way too high.

You can have many times the input DC current circulating through your mosfets and with hard switching, fr that power level, things just don't look good.


That's where large ferrite transformer skips in - at least in my theory, it should ensure efficient energy transfer, and although audio-modulation would cause hard switching, keep the mosfets happy.

That is, necessarily a ferrite transformer.

I don't think that should be any harder than designing a class D amp for the same power level, but I'm no expert.

That's probably something that would need some ugly prototyping before plexing it up.

I'd really like to see Steve W.'s thoughts on that!



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Dr. Spark
Tue Nov 27 2007, 02:52PM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Marko wrote ...

That's probably something that would need some ugly prototyping before plexing it up.

I'd really like to see Steve W.'s thoughts on that!







Hi Marko,

Yes will proto type before ever going into Plexy. Been working with a surprise for the thon…….and talk about proto type; however, down to only one table now……..@ and yes that is a CM600 brick running the grid………wheeeeeeeeeeeeee.

What I love about this hobby is all the experimentation it takes to be successful, the more play the better the coil works.


This will be a fun project indeed.


Cheers,
ch



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Dr. Spark
Mon Dec 03 2007, 04:21AM
Registered Member #290
Joined: Mon Mar 06 2006, 08:24PM
Location: Arizona, USA
Posts: 1624
Good day,

Demo the bi-polar audio coil at the mini thon this weekend, notice starting with blue LEDs at top and migrating to red at base.


video @


Cheers,
Ch
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Chris Russell
Thu May 21 2009, 03:28PM
... not Russel!

Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1082
I just featured this project on the front page, so I wanted to break the ice in case nobody wanted to be the first to post in over a year.

Congrats, Dr. Spark! Another stunning project.
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quicksilver
Thu May 21 2009, 04:45PM
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Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
I did indeed accept the gracious offer of Dr. Spark to witness this and many other projects several months back in the "garage of wonder".... It was the final seed to get me hooked.

The meticulous nature of the gentleman's construction was really what sealed the deal for me. I love seeing something DONE RIGHT!

Plexiglas is not too difficult to "clean-up" if a scratch exists, etc and it really allows an element of creativity to a project that makes the piece a keeper. I have made a few little toys here and there but they didn't "look" attractive; regardless of the clean solder points, layout, or what have you.

There is a Hell of a lot of creativity in the good doctor's work - but there is also style. And that can make the difference between working on a project and then let it go after a great amount of effort - And KEEPING that project alive!
In my opinion, that has great impact in the HV hobby.
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