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Red Traffic Cone - new SSTC with conical secondary - full power

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LAN_403

Mates

Thu Oct 15 2009, 11:43AM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

A small update - the power is rising... The picture below shows 60% power (cca 150V). Unfortunately the really impresive 100% power destroyed one of my IGBT's before I could take the photo

It seems that for the 2,5KW power I'm sucking from the wall (at full power) I need more robust driver construction. I plan to switch sooner or later to a bridge design anyway... I'll keep you updated

Killa-X

Thu Oct 15 2009, 11:32PM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

That's why its nice if you own a dedicated cam corder. You record video, go back and edit the video, frame by frame, and make a photo out of one of the frames. If you have a good cam corder it comes out very nice. My camera, made for pictures, can get decent pictures out of video, but usually not as big as i like (1280X1024+)

Mates

Fri Oct 16 2009, 10:31PM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

New update...

I finally made an interrupter for my single switch driver! It means no more heating of my transistors. I also discovered one very interesting option about the new coil. In spite of the classical coil the best performance of the conical secondary is when the primary is as low as possible (why?).

The improvement in the performance is quite astonishing. I used maximum only 150V (around 60% of the power) and as you can see on the video the sparks length, my guess, might be around 40cm. I think it is not bad for a coil without feedback.

I will experiment with the primary a bit more before I will try the full power...

Here is the video - maximum 150V

Herr Zapp

Sat Oct 17 2009, 12:43AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Mates -

Can you clarify the driver topology you are using on this coil? You mention a "single switch driver". but state that your new interrupter has reduced the heating of your "transistors" (plural).

Is this a half-bridge driver, with two IGBTs?

Thanks!
Herr Zapp

Mates

Sat Oct 17 2009, 07:12AM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

Herr Zapp wrote ...

Mates -

Can you clarify the driver topology you are using on this coil? You mention a "single switch driver". but state that your new interrupter has reduced the heating of your "transistors" (plural).

Is this a half-bridge driver, with two IGBTs?

Thanks!
Herr Zapp

Explanation is simple - it employs three BUP314 IGBT transistors in parallel...

Hon1nbo

Sat Oct 17 2009, 04:17PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042

Very Nice Work! - but I do have a thought about winding the conical form: would it not be best to do it upright? I think it would be cause any sliding would not be likely because of the wire beneath it, and it would likely allow more control
I could be wrong but it is just a thought

again great work
-Jimmy

Mates

Sat Oct 17 2009, 04:49PM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

DaJJHman wrote ...

...but I do have a thought about winding the conical form: would it not be best to do it upright? I think it would be cause any sliding would not be likely because of the wire beneath it, and it would likely allow more control
I could be wrong but it is just a thought

Hi,
It seems there is still some misunderstanding in my winding approachâ€¦

So, just to make things absolutely clear for potential followers - there is only one possible way for winding the wire on a conical shape. You have to start at the tip of the conus and than continue to the base of the conus (from the smaller diameter to the bigger diameter). The wire beneath each turn indeed blocks the new turns from sliding, but it can still happened and once it happens than you might loose the whole work (it happened to me twice!). That's why I used the approach of fixing approx. 5cm finished sections by polish and glue tape.

Cheer Mates

LTX

Sun Oct 18 2009, 09:47AM

Registered Member #2435 Joined: Thu Oct 15 2009, 06:47AM
Location: Sopotnice, Czech Republic
Posts: 5

Hi Mates

This is very nice work. Really great idea !!

Herr Zapp

Sun Oct 18 2009, 05:21PM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Mates -

I wound a conical coil on a machined wooden form, not as long as yours, but with a similar cone angle.

To align and support the critical first few turns at the small end, I applied "band" of 8-10 layers of 3/8" wide masking tape a few inches from the end of the cone to form a "shoulder" for the wire to butt up against. This eliminated any tendency for the windings to slip on the form.

Obviously, the smaller the wire gage and the steeper the cone angle is, the more difficult the process becomes. Tension is critical; either too much, or too little will cause a disaster when the windings slip over each other.

Regards,
Herr Zapp

Steve Conner

Sun Oct 18 2009, 06:28PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I like it! :D

I wanted to make something similar myself, but couldn't figure out how to wind the secondary without all of the wire just falling off, so I never even got started. Hats off to you!

I think the low primary works well because it's very close to the base turns of the secondary. The conical shape means that the base turns will contribute more to coupling than the upper ones, because they have more inductance on account of their larger area.

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