SSTC for School / Projects / Forums

Forums

4hv.org :: Forums :: Projects

« Previous topic | Next topic »

SSTC for School

previous 1 2 3 4 next

Move Thread

LAN_403

Marko

Fri May 04 2007, 12:06PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hi

The one on page 10 is a sort of final application, although while I played with the circuit I couldn't figure out the exact purpose of that diode bridge stuck over the timing capacitor.
That's one thing I really failed to get any clue about!

The circuit does pretty much the same as steve's version but in a simpler and more straightforward way.

The cap charges through a resistor, and triac is triggered by a diac. But, one small triac is also triggered wich then 'shorts out' the high value potentiometer making the RC time constant very small; diac then fires many times more until the end of the cycle generating a pulse train for main triac.

So the page 11 circuit should also work and only thing that would need to be added is a snubber across the triac.

Still I think this needs to be checked by the proffesional (Steve) before I make more assumptions.

Regardiing the input voltage, 110V should worka s well, dissipation will be less and timing slower (although you could easily fix that).

CT2

Fri May 04 2007, 07:14PM

Registered Member #180 Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187

Ok, so I should be able to use the one on page 11. As for the snubber could I just use the same values as the one on page 10? I was also not too sure what values should be used for the components, would these work? And where does the gate of the second triac across the potentiometer connect? Is it to the cap, so anode and gate connected?

Marko

Sat May 05 2007, 01:09PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

You connect the gate of auxiliary triac as in schematic on page 10.

And do use a large PFC inductor in series (Look at steve's OLTC power supply) if you plan to have bulk capacitors in series with output.

But, dimmed and unsmoothed supply voltage can sometimes give interesting spark effects.

CT2

Tue May 15 2007, 03:06AM

Registered Member #180 Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187

Ok so I'm almost done the coil now. I haven't been able to do everything I wanted to with it because I've pretty much run out of time, so I wound a smaller coil and whent with this design. It is a PLL driver and a half bridge with audio mod (I know I didn't want to use either for this project but time is running out). The coil however is small and low power so there shouldn't be any problems once I tune it initially; my test coil ran flawless so I'm hoping the same with this. I still have to finish the enclosure, there will be another piece of acrylic ontop suported by 1/4" threaded rod (atleast I think thats what I'll do) and probably acrylic walls on the sides with the power switches and indicating lights. All in all I think it will be a nice little coil and I am already sad that I have to depart with it... any advice still very much appreciated, so let me know if I should change something up!

Steve Ward

Tue May 15 2007, 03:59AM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

The only thing i might change is the magnet wire on the GDT to something with plastic insulation. Ive had too many GDTs wound with magnet wire fail.

CT2

Wed May 16 2007, 03:14AM

Registered Member #180 Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187

Tonight I pretty finished the 'case' for the coil. All thats left to do is build the primary+topload, wire everything up, fasten any loose wires down, and tune it. Hopefully I can have it completely done by the end of the week or next monday. And thanks for the advice steve, I'll try and find some adequate wire and wind a new GDT, I think I remember hearing that phone line is pretty good so ill try and get some of that, oh and I'll also add bigger resistors on the gate (1/4 W ones are getting toasty

Coronafix

Wed May 16 2007, 10:15AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Nice work Chris. I like the 'case'.

Brett Miller

Wed May 16 2007, 05:09PM

Registered Member #593 Joined: Tue Mar 20 2007, 12:32AM
Location:
Posts: 50

CT2,

Great Work! Make sure you post some spark pictures...I've been using a half bridge version of the MiniSSTC for months now, with no failures whatsoever. I've gotten up to 14" sparks, I use a 12.5" x 4.5" secondary of AWG 31, with a rather large 11.75" x 2.75" toroid over a 6" lower toroid. I get around 170Khz from that setup and the MOSFETS run cold unless I remove the interrupter and run CW. Even then they stay cool unless I'm constantly drawing flaming power arcs.

-Brett

CT2

Tue May 22 2007, 03:43AM

Registered Member #180 Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187

OK so today I got it all hooked up and started testing. When hooked to mains (110V) then rectified and filtered I get ALOT of power from it, but not the biggest sparks... I can draw like 6.5" flamming white arcs from it, but it only gives off maybe 3-4" firey streamers. I don't have a propper topload yet so maybe that will help, but does anyone have any ideas on how to increase streamer length (I've always found it hard with smaller coils)? I also tried out the audio mod and was damn surprised by how loud this little coil is, I have to speak pretty loud to talk over it, it's also very clear. Here's a vid of it Link

ragnar

Tue May 22 2007, 05:01AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

That probably sounds about right for CW. Adding the interrupter will alter the spark appearance (and length).

Unlikely, but if you were driving it at an odd harmonic of the resonant frequency, you'd probably get weird/small sparks, so perhaps just check

Altering the envelope (by feeding it fullwave/halfwave rectified mains) will also affect the appearance...

previous 1 2 3 4 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob