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My first SSTC

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LAN_403

Dieu

Sun Dec 21 2008, 02:34PM

Registered Member #1730 Joined: Thu Oct 02 2008, 08:12AM
Location: Poland
Posts: 35

Ok. I new here, but I have some experience witch HV.
Here is my first SSTC. Some foto

Here is my secondary(just srarted), drivers (TC4422 and TC4421) with interrupter and half-bridge on IGBT MG16Q6ES42. I don't have variac, so it will be running on 230V.
Can I conect GND from my secondary and primary?

LithiumLord

Sun Dec 21 2008, 04:14PM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

Better get a variac or at least some low-voltage source as tweaking would require some of that. However even at least some lightbulb ballast could go on early debug stages, but that's not very optimal.
Nice circuitry, is it feedback-based or open-loop? Now you only need some good screened casings for it.
For the interruptor - better make it either external or an internal one that uses external startup strobe fed from a handheld controller, also add a driver-level on/off switch there as it's pretty easy to use this way.
BTW how big is the secondary?

As for the ground, better use separate ground points - myself I prefer using mains as primary ground (just as the bridge is rigged there directly) while cases and secondary share the actual ground wire. A bypass from bridge onto the actual ground via a capacitor is recommended, however I'm not using it atm.

Dieu

Sun Dec 21 2008, 05:23PM

Registered Member #1730 Joined: Thu Oct 02 2008, 08:12AM
Location: Poland
Posts: 35

Driver have feedback with antenna. Interrupter is 555 with reg. of on/off time. Hight of secondary is around 50cm 0.1 DNE, that gives 50kHz.
I will be starting my SSTC on 30V (100W).
I was wander, that can I make it more mobile, like for show, just one cable to grid.

LithiumLord

Sun Dec 21 2008, 09:05PM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

Hehe and one cable concept doesn't interfer with the ground issues - in a generic hot-neutral-ground 3-pin sucket you rig your cases/electronics etc to the ground wire while the primary remains grounded through the mains. Otherwise you are forced to either use a 4-pin 3 fase-grounded neutral socket or keep checking the neutral wire is actually the neutral one, not the hot one, every time you plug the system in. Also the usage of the neutral wire sometimes gives problems with up to like 30vac displacement voltage, and also any differential protection would kick off. So, as far as nearly every place you could run this has the 3-pin sockets, the separate ground is the best choice.
For the secondary, 50cm is a pretty high one, this would surely need a complete H-bridge to run off-wall in order for the sparks be of the same height as it is. Also the 0.1mm wire seems very thin, myself I use 0.3mm wire on a ~35cm high coil, ~200kHz unloaded, it runs a bit warm (running 84bps@30% d/c with quite a power - over 60cm breakout) - however my old 300kHz one that was wound with 0.18 wire ran very hot, no matter that one didn't get much over 30cm sparks. So with 0.1mm wire even on 50kHz it may run really very hot, especially with the power you'd like to feed into one. By the way, this also adds some power loss.

Dylan

Mon Dec 22 2008, 05:20AM

Registered Member #1024 Joined: Sun Sept 23 2007, 10:56AM
Location: Northern NSW, Australia
Posts: 95

I second LitiumLords advice on grounding, it should be fine at 30V testing to use the mains ground for the secondary, but for full mains (approach this voltage carefully

) you should really have a dedicated RF ground for the secondary tank.

Anyway, nice work! very tidy.

Dieu

Tue Dec 30 2008, 12:13PM

Registered Member #1730 Joined: Thu Oct 02 2008, 08:12AM
Location: Poland
Posts: 35

Here is my secondary, almost finished. I have to lacquer it.
But here is problem: how many turns it need for primary? 5? 15? 30?
It take some time to make power supply, so I be trying to find something.
In future it will be enlarge to Dual Resonate :D

Kizmo

Tue Dec 30 2008, 04:05PM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

I would start with 15-20 primary turns

Dieu

Thu Jan 01 2009, 08:46PM

Registered Member #1730 Joined: Thu Oct 02 2008, 08:12AM
Location: Poland
Posts: 35

Its not my. The question is, what for are this 5 coils on ferrit core?

One more thing, how to make GND for my SSTC, at 3 floor?

LithiumLord

Thu Jan 01 2009, 10:30PM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

According to the presence of the thick-tough-wire coming through three of them and the rails on the PCB, two of them are meant for feedback, the other single one is for the current sensor and the second couple, according to the text on the PCB is just a test CT to get scope traces from.

As for the ground, either use a powerline ground (usually wired through those 3-pin sockets), an antenna ground (check for interference issues however ;) ), a hand-made dedicated ground you'll have to make or just a water pipe. However mind the power, it's not a very good idea to ground a 2kVa coil through your water pipes! ;)

Dieu

Fri Jan 02 2009, 02:27PM

Registered Member #1730 Joined: Thu Oct 02 2008, 08:12AM
Location: Poland
Posts: 35

Thanks!
But I need to give it some filtr to prevent interference in grid.

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