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Second solid state tesla coil, PLL audiomod.

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LAN_403

Arcstarter

Tue Mar 17 2009, 03:37AM

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

Wanted a slight upgrade form the mini, so i decided to go for PLL with audio mod. The purpose was not for spark length, but better stability and AUDIO MOD OMG. Hehe. I currently have no scope or freq meter, so until i get one i am not going to do any power upgrades or anything.

I am not achieving a freq lock, and the heating is bad. I am rather sure if i took the feedback off, it would run the same way. Rather pointless it seems, but audiomod is still fun :P.

I used Uzzors' schematic, with a bunch of modifications :P I used different values for everything, and in series with the 10nf capacitor near pin 9 (trying to remember, lol) i put a 180 ohm resistor to ground. In the middle of the cap and resistor, is my + audio input, and the ground goes to ground.

The UCC's are currently from my old sstc board, hooked to the pll driver board. I am just too lazy :P. When i fix that, i am sure i will have less heating DX. the layout is very messy, so i surely have parasitic inductance and capacitance, which leads to parasitic oscillations. So, i usually run at 50vac into the bridge, but sometimes i will change to 100vac. The capacitor(s) is(are) 2 80 volt 100v surge 22000uf in series for 11kuf and 160vdc. I have a slight hiss, but that is it.

Audio input is my Zen :). I have tested many times with a crap radio, and i never had any problems, moved to ipod shuffle, and now this. One time i had an arc jump from me to the Zen, which shut it off but she still works fine. Just remember, this thing has enough RF power to make me arc to anything metal even one room away, so the Zen indecent could have happened even if i was not using it for the audiomod. I now hook the Zen to my spare pair of speakers with integrated amp, and hook the sstc to that, for a tiny bit extra isolation.

I would like to thank Avi (arots on youtube) for the idea, and a TON of help! If it was not for him, i would not have made this thing in the first place! Thanks!

Videos:

(cruddy sounding, no lights)

(with lights and better smoothing.

Chris Cristini

Tue Mar 17 2009, 06:33AM

Registered Member #1749 Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497

That is cool man good song to.

...

Tue Mar 17 2009, 07:34PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Nothing like some some system of a down and 3 days grace playing on the tesla coil

Ironically that very album (one x) was what I used to tune up my coil

I would comment, I think your coil would benefit from a bit from more modulation, either by adding a preamp after your mp3 player, or reducing the tuning range (those 2 resistors on like pins 11 and 12 IIRC). The preamp is more complicated, but reducing the tuning range reduces your ability to change breakout points/etc

With my coil

I pull about 3 amps with a good center frequency (you want to be under the resonant frequency to the point where the sparks are 1/2 to 2/3 their size at full power) and can fill a decent size room with audio similar to a set of laptop speakers (running about 700khz with the current secondary)

One last thing you might try, I found that the pll part ended up being more of a pain than it was worth, so I reconfigured the driver to be a simple VCO (you can ground pin 14 and leave the circuit unchanged to run in this mode). Then you can use the normal tuning pot for fine tuning of the center frequency, the resistors on 11/12 to set the course center frequency and the tuning range, and just tweak the tuning pot to change the bias or account for different toploads.

Arcstarter

Tue Mar 17 2009, 07:47PM

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

Heh, didn't think anyone liked SOAD or three days grace. Lol.

That is cool man good song to.

Heh, thanks :P.

Anyway, nice coil '...'. (looks like a face :D) I have to do a ton of stuff before i am satisfied, but if i can ever get a scope, that will be easy (enough). I am not satisfied at all with it right now, i would not even consider it better than nothing (actually worse, it costs me a bunch of mosfets!). I am out of mosfets now (thanks shoot-through and little/no deadtime!) so when i find a scope i will begin on it again.

Next few upgrades would be finishing the board, get the tuning and timing cap correct, boxing it all up, and making a new primary. I also need to switch on of the heatsinks to match the other. I am expecting in the end around 8 inch arcs with the full 120 volts in.

Already have the next audiomod song figured out :P.

kilovolt

Tue Mar 17 2009, 08:03PM

Registered Member #2018 Joined: Tue Mar 10 2009, 09:56AM
Location: Switzerland
Posts: 74

Very nice work!

Especially when i'm imagine that you built this coil without a scope, well done! Great audio quality... is this made with a halfbridge design?

Regards kilovolt

Arcstarter

Tue Mar 17 2009, 08:14PM

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

kilovolt wrote ...

Very nice work!

Especially when i'm imagine that you built this coil without a scope, well done! Great audio quality... is this made with a halfbridge design?

Regards kilovolt

Thanks :D. I cant wait for a scope :P.

Yes, this is halfbridge of some cruddy 20 amp 500 volt mosfets, that seem too slow to ge tthe job done. I have two completely different fast diodes on the halfbridge, but it has not given me a bit of problems yet. I will upgrade that when i get it all working good.

Arcstarter

Tue Mar 31 2009, 08:37PM

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

I am currently fixing the sstc driver up a bit. I added the UCC's on the board finally. They work, and i got tiny arcs on the coil. I know the reason for the size. Suddenly the 4046 is oscillating at around 650khz (measured with freq meter). The capacitor is the same though, and i checked to still be 1nf. The 4046 puts out 650khz, it is the same freq all the way after the ucc's. Also, the 555 stopped working, and i was not working on anything near that or the 4046! The voltage has raised a bit, but still at a safe 12.11 volts :P. The 4046 still has a 50% duty cycle output. I hooked everything up and switched phasing on the CT up, to no avail.

I made two simple corona motors, one better than the other. I took the first ones link off, as it is a bad video.

This one looks cooler :P. Sorry about the shakiness, it was 3 in the morning.

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