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~2kW PLL SSTC

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brtaman

Sat Sept 05 2009, 10:24PM

Registered Member #2161 Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247

Hey guys,

Just finished up a PLL SSTC a copy off Steve Conners work, but I used the schematic from Uzzors website as it is much easier to follow. :) I am really happy with the circuit, Steve Wards MiniSSTC circuits was giving me all sorts of trouble, though this was my fault the 74HC14s kept dying or producing deformed signals, which is something I realized when I finally bought an o-scope...after killing about 23 IRFP460s -.-

Full-wave filtered

Half-wave unfiltered

Picture of secondary. :O Looks a lot worse than it is though. ;)

Here are some specs:

Secondary:
H: 16.2 cm
W: 9 cm
Freq: ~520kHz based on scope measurement, making the wire 33AWG with 757 turns.

PLL schematic is exactly the same as Conners and Uzzors, but with a 270pF cap on the 4046 with 10k and 15k ohm resistors, giving the driver a range from 454-724kHz. I also added 16v 2200 uF(!!!) caps right on the UCC's, it is overkill...but it was all I had, you can see them sticking out of the driver on the video. :)

IRFPS29N60 mosfets (A MUCH tougher customer than the 460)
0.56 uF 400V caps. (it was all I had with decent dv/dt, would bumping up to 0.68 help performance?)
MUR1560 diodes
7 ohm gate resistors

GDT:
0.33uF DC blocking cap
14-turns
Ferrite Toroid specs:
ui: 6000
AL: 7800
36mm 24mm 16mm

____________________________________________ __________________________________________________ _
Phase II

Found some spare time an upgraded the coil. The RF arcs are now pretty decent.

New CW video

New secondary:

Height: 50cm
Width: 10cm

With torroid frequency is around 220 kHz.

The coil has now been upgraded to full-bridge. Next step is interrupter.

Thanks
brtaman

Arcstarter

Sun Sept 06 2009, 02:03AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

F**king awesome!

Very nice plasma plume. That is alot of power.

So, are you using antenna or CT feedback? If it is antenna, you can try CT and see if it helps. It was best for me, worked alot better, with less heat and explosions.

Audio modulation is just a matter of adding a ~100 ohm resistor after the capacitor that goes to pin 9, to ground. Where the capacitor and resistor connect is the audio input, and common ground is of course ground. It will sound VERY nice! And with that much power, that will be one of the coolest audio sstcs on youtube... Sounds as good as a lower quality speaker.

Good job, and good luck!

brtaman

Sun Sept 06 2009, 10:29AM

Registered Member #2161 Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247

Thanks arcstarter!

It is still running an antenna, the wire is to thin that it is barelly visible in the video, all the high permeability toriods i have are huge. -.-

ScotchTapeLord

Sun Sept 06 2009, 01:40PM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

Wow. That is one of the coolest CW systems I've seen. I hope mine looks like that! You may not have the same streamers as everyone else, but that is one seriously powerful coil!

brtaman

Sun Sept 06 2009, 02:41PM

Registered Member #2161 Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247

Hey,

Thanks for the kind words ScotchTapeLord (lol, cool name). I am very pleased with the coil, just please get an o-scope when you start making your :P (if you don't already have one) it will save you all sorts of headache and pay for itself quite quickly. (Haven't killed a FET since I bought my o-scope, was a serial killer before(confirmed death count >>20 $$$ -.-))

I have added a new video, using half-wave rectification (MUR1560, all I have on hand that can handle the power) with no filter the sparks have increased to ~25cm! :D They are very VTTC like though, which I would love to see when I build my VTTC not as much in this case. It has the a more pronounced buzzing sound now.

The bridge is now heating A LOT less. Can't wait to add a torroid and go full-bridge. The difference in arc power is quite pronounced though.

Thanks
brtaman

uzzors2k

Sun Sept 06 2009, 03:07PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Good job! The streamers are at least as long as the secondary, so you've certainly succeeded in making a good coil. How big was the filter capacitor? Using a "big" filter capacitor will always trip the breaker. Anything over 500ÂµF causes too much of a surge when first turned on to simply be plugged straight into the wall. Have you seen my full-bridge multipurpose inverter? I put a lightbulb in series with the line, and a switch in parallel with the lightbulb. This allows for large filter capacitors to be precharged before connecting directly to mains.

ScotchTapeLord

Sun Sept 06 2009, 03:35PM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

I have a 'scope, and it is of course, very handy. It isn't calibrated and I don't really know how to do anything but trace a signal and adjust the axes, but that has been fine for me so far. Unfortunately I am at college and far from it at the moment. Fortunately, they have better ones here! If only I could find them...

I have definitely killed FETs since having my o-scope, but when I learn how to use it better, I'm sure things will improve ;)

EDIT: Oh, and thanks for the compliment on the name :D It's been my internet alias for about six years now, made long before I made the switch to electrical tape. But I've found that scotch tape can often do electrical tape's job ;)

GeordieBoy

Sun Sept 06 2009, 05:26PM

Registered Member #1232 Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881

Nice CW SSTC, and some nice spark videos too.

I would issue a word of caution about pulling sparks to an un-grounded screwdriver though. At these power levels it can instantly track over the plastic handle or eventually burn through the handle to get to you if the metal shaft is not grounded! I know this from experience, and the result is either a painful shock, a deep burn or both!

Those at the Cambridge Teslathon a few years back will remember me throwing a screwdriver across the room after what was meant to be a tiny "tuning spark" flashed along the plastic sleeve and over the handle of an insulated screwdriver!

-Richie,

brtaman

Sun Sept 06 2009, 06:20PM

Registered Member #2161 Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247

Hey,

Thanks everyone from your comments, I can honestly say it would not have been possible without your work and webpages.

Uzzors: Thanks for the tip, as a matter of fact the smoothing cap was exactly 500uF (2x 200V 1000uF caps in series). I will look into making the into making your multipurpose inverter after I figure out the best way to interrupt the coil, in CW Half-wave is much nicer even though full-wave does put out some impressive rf arcs, I was just going to go for the standard 555 into the no.3 pins, but I was looking over Steve Conners website and he used 2IC's before the enable pins, so I am a bit hesitant. I guess full-bridge is the next step for me as well.

Richie: Thanks for the tip! Arcing through the screwdriver is a regular occurrence on my flyback tesla coil, but the 120W basically just tingles. Will ground the screwdriver for this coil. I really don't want to experience a kW of RF on my fingers. ;)

On a side note, now that the breaker doesn't pop every other time I increased coupling, performance has increase by another 5-7cm. Until I increased coupling another 4mm up and the primary flashed so bad it caught fire, again I have to say the IRFPS29N60's are tough tough bastards. :O

All is well on the coil though, I am extremely happy that I used an acrylic water based varnish, which when dried is like another plastic shell, there is a few burn marks on it, but it is still fully operational and the wires is completely undamaged. I think that if I had used my regular varnish this secondary would be toast, literally. Well at least I now have a nice scorch mark on the secondary telling how high I can place the primary? I really recommend this type of varnish for anyone planning a CW SSTC coil.

uzzors2k

Sun Sept 06 2009, 09:14PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

I didn't mean the full-blown inverter, just the lightbulb trick.

You'll need to turn your driver on after the capacitor has charged and the power switch is thrown, or it will try to run through the lightbulb!

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