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Dr. Dark Current

Sat Dec 20 2008, 07:32AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Erlend^SE wrote ...

For Dr. Kilovolt: I am not the one that asked how to start, but I am interested in seeing your SMPS IC driver, and I think others may too be interested.

Got some flybacks on orginal board driven by SMPS controller here, maybe I try to reverse enginer it more and post scematics sometime if anyone ask for it?

Ok here it goes:

If you want to use just a single MOSFET, double the gate resistor (330R).

"duty cycle" adjusts power. Set frequency to around 20kHz for best results.

Cwiber92

Sat Dec 27 2008, 06:05AM

Registered Member #1858 Joined: Fri Dec 12 2008, 05:17AM
Location:
Posts: 9

I finished building everything and everything works perfectly, thanks to all of you. The plasma arc is so sick. Here are some pics.

Myke

Sat Dec 27 2008, 06:15AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Nice! Do the primary wires heat up at all after a while of operating?

Arcstarter

Sat Dec 27 2008, 06:20AM

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

Very nice! You completely skipped the simple single transistor driver to ZVS :). You might want to make the wires shorter and MUCH thicker. I pump so much power through mine, the 12 gauge wire connecting the drains of the semiconductors(i say that because i have used mosfets and igbts, which was a big mistake, i now have one blown 72 amp 1200volt igbt, after it worked for awhile) would actually melt the insulation after somewhat long runs.

The thing that amazed me was not only the arc thickness, but the heat. I just sat there the first time i fired it up at 740 watts, and wondered where the heat went. I was speechless.

I would never have expected 12 gauge wire to get hotter than the TINY die of an irfp250. I blew one of the irfp250's which is why i used the igbt, and the irfp250 never got more than a few degrees above room temperature.

You can use it for an induction heater. I used a 14(i think) center tapped turns, about an inch in diameter and used 40 volts input and it would turn a large nail red in maybe 10 seconds.

rp181

Sat Dec 27 2008, 03:25PM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

Thats why ZVS is so great. It allows lots of power because of the Zero-volt-switching part, which means very low switching losses.

Dr. Dark Current

Sat Dec 27 2008, 05:54PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

rp181 wrote ...

Thats why ZVS is so great. It allows lots of power because of the Zero-volt-switching part, which means very low switching losses.

It's mianly because the transistors don't have to switch the reactive or apparent power, it circulates between the core and the resonant cap. Other drivers need to switch that apparent power, which is 4 times the maximum output real power, when you short-circuit the output.
A simple check for this is that the transistors switch just little current when the output is shorted.

Cwiber92

Sun Dec 28 2008, 12:52AM

Registered Member #1858 Joined: Fri Dec 12 2008, 05:17AM
Location:
Posts: 9

Yeah the primary winding gets warm after a little bit, all I had was 22 gauge. But I don't plan to use it continuously, so it's good enough for now.

Cwiber92

Mon Dec 29 2008, 08:05AM

Registered Member #1858 Joined: Fri Dec 12 2008, 05:17AM
Location:
Posts: 9

I sorta rebuilt my ZVS with 12 gauge wire and a 14 gauge primary. Everything was heating up much less and working fine until my primary suddenly burst into flames. I felt the flyback transformer and it was very hot. Did I blow the flyback?

Rut roh:

Dr. Dark Current

Mon Dec 29 2008, 08:30AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Cwiber92 wrote ...

I sorta rebuilt my ZVS with 12 gauge wire and a 14 gauge primary. Everything was heating up much less and working fine until my primary suddenly burst into flames. I felt the flyback transformer and it was very hot. Did I blow the flyback?

Probably not. I think it was the plastic insulation which caught on fire, try to rewind it with an enameled wire on some kind of a former if possible, if not just insulate the core with a few layers of paper (do not use plastic, it WILL melt).

Cwiber92

Thu Jan 08 2009, 06:01AM

Registered Member #1858 Joined: Fri Dec 12 2008, 05:17AM
Location:
Posts: 9

I've got everything running again. A few questions: the 3W 470 ohm resistors get the hottest of anything, is this normal? Anything I can add to take heat away from them? How can I approximate the output voltage? Sorry, but I must ask, what would happen if you were to get shocked by the output either across your whole body or say on one finger?
Right now I'm burning different metals and observing their colored flames, pretty cool.

Thanks

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