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Need help with steve wards class e sstc.

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Arcstarter

Tue May 06 2008, 05:37PM

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

I have it running i guess but i got better spaarks with the 555 and mosfet sstc! I have tried tuning it and changing the resonant capacitor and i still get very small sparks... And whenever i change the 100kohm pot down(or up) the sparks stop all together! It is inturupting right and when i change the 200kohm pot i get different interrupt rates. Also the mosfet gets really hot really fast. I have a big heatsink on it too. I use a seperate 12 volt source and coil supply source, may this be the problem? The 12 volt source is unregulated for now and the coil power source is a 50 volt transformer with a bridge rectifier and a smoothing cap with a value of 470uf.

UPDATE: I just went over the schematics and i got everything but the power source exactly like steve did. I just cannot seem to get worthwhile sparks out of it. I used a 2 inch diameter coil form and i am at about 7 turns primary and 1nf capacitor.

uzzors2k

Tue May 06 2008, 09:12PM

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

Could you post some waveforms? Gate and drain would be nice, preferably with a dual trace scope.

You may be running the coil itself out of tune, but have the primary and "class E cap" in tune at a different frequency than the secondary fres.

Arcstarter

Tue May 06 2008, 10:12PM

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

Don't have a scope... I have been messing with it and i went and got my 4 inch secondary and i still don't get visible sparks, they are audible, but more like a static spark. The strange thing is that wen i touch the antenna, the sparks are visible and longer. Does this mean that i am dot getting a strong enough feedback signal? My antenna is about 4-5 inches long and for the 'capacitor' wound around it i have around 6-10 turns...
I have the coil around 6inches away from the antenna, so as you can see, I am quite puzzled.

teslacoolguy

Tue May 06 2008, 10:57PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

I would try to make a longer antenna 8-9" and wind 7 turns around it because thats what i did when i made it and it seems to work well. also how far is the antenna from the coil because if it is more than 3-4" away the antenna will not pick up the feedback signals strong inough to put the circut in resonance.

MRacerxdl

Wed May 07 2008, 12:34AM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

On the first SSTC that I did make I was have the same problem. It can be two things:

First your antena is not receiving a good signal from secondary coil, try to get it closer (if you have the two clamp diodes thats not a problem if get a little corona on tc)
Try to make a longer antena like teslacoolguy say too.

Other things you have a antena too close of sstc, So you need to do exactly the inverse that I have said before.

Try to manage the position of antena and the size of it to get optimum sparks.

Arcstarter

Wed May 07 2008, 01:38AM

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

Well i now have like .20 inch sparks :(. I took the wire that wraps around the antenna off because i have this on a breadboard so it already has enough capacitance(yes i know that is a no-no). It still used enough power to heat up the mosfet in like 2 minutes so hot it cannot be comfortably touched. I have never been so puzzled. I have planned this experiment for many months so this is a huge disappointment, as you can imagine.

Oh, and i get no streamers or corona or whatever, and I am PO'd

teslacoolguy

Wed May 07 2008, 02:13AM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

How close is your primary to the secondary and how many turns is it?

Arcstarter

Wed May 07 2008, 02:22AM

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

6 turns and about a foot away from antenna.

Ok i messed with the secondary and i now have a tiny streamer.
I can not get any better performance when trying to tune though

teslacoolguy

Wed May 07 2008, 03:56AM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

Ok reduce the primary to 1-1.5 turns.

Arcstarter

Wed May 07 2008, 03:58AM

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

I dont even get a spark at 1 turn.

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