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SGTC using ZVS Fly back.

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Danielle

Sat Jun 02 2007, 05:49PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

ok so I got some of my parts together and decided to build a small Tesla coil with a fly back transformer. Here are some pics of parts I have on hand. my main 3 questions are is the bottle caps enough, 2 can I use 33v zeners and drive the gate harder, and 3 is the ferrite core good enough how it is wrapped or should I re wrap it for the primary inductor.

Tonic

Sat Jun 02 2007, 06:43PM

Registered Member #528 Joined: Fri Feb 16 2007, 10:32PM
Location: Warsaw, Poland
Posts: 166

Rocketry76 wrote ...

ok so I got some of my parts together and decided to build a small Tesla coil with a fly back transformer. Here are some pics of parts I have on hand. my main 3 questions are is the bottle caps enough, 2 can I use 33v zeners and drive the gate harder, and 3 is the ferrite core good enough how it is wrapped or should I re wrap it for the primary inductor.

I'm looking forward to this project! :)

First question - I don't know since I'm lacking the knowledge about tesla coils

Second question - It depends on that what transistors you use. You should check their datasheet and read, what's gate maximum voltage (my transistors I've used for ZVS driver had usually max. 20V. Exceeding this rate may kill them). What are transistor's model names?

Third question - hm, inductor's wiring is done properly, but what I've seen in topics about ZVS drivers, the 30 turns is a common amount. Although it may work - there oscilloscope would be useful (do you have it?) - plug scope into inductor's output and check if you have a sinusoidal waveform. If not, you may need to increase inductance. If inductor decreases peak voltage/current, decrease inductance until you get peak v/c (but you must also keep sinusoidal shape).

Danielle

Sat Jun 02 2007, 06:59PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

thanks I have the 30N60s and 50N100 to play with. no I dont have a scope yet but I will soon. I am curently fixing my SSTC driver and building an interupter while working on this I have seen many people run SSTC IGBTs at 30 V so I thought I could do the same with this. Thanks

Coronafix

Sat Jun 02 2007, 11:12PM

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

Your bottle cap size will depend on the frequency that the driver is working at,
according to the formula : Resonant Cap = 1/(2xpixZxf)
where f = frequency of transformer
Z = V/I
So if your driver is running at about 20kHz
and putting out 100W @ 10kV for example.
(forgive me if these figures are way out, I don't know enough about
the ZVS driver to know)
then your resonant cap value will be a meager 8pF
Maybe all this doesn't matter and one bottle cap will work fine.

Brett Miller

Sun Jun 03 2007, 04:24AM

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

Daniel,

I've built 5 zvs drivers, and I've run them up to 50v for about 5" flaming white hot arcs from a DC flyback. It makes a nice quick jacob's ladder that equals or surpasses one from a 12/60 - 15/60 NST. It's cool to hear the hissing of the arc rather than 60hz buzz for a change.

Anyway, on the original schematic that Vladi (Mazzilli) drew there is a mistake. He apparently switched the drain and source. If you build it directly from that schematic it will not work unless you switch those connections on your FETs/IGBTs. I figured that out, and I think others have too...years ago, yet that schematic is still in wide circulation, kind of weird, but anyway, be careful with that driver...it can deliver a lot of current.

-Brett

Avi

Sun Jun 03 2007, 07:41AM

Registered Member #580 Joined: Mon Mar 12 2007, 03:17PM
Location: Melbourne, Australia
Posts: 410

So is there an updated schematic with the drain and source fixed and/or modification with the 35% more performance?
(sorry I could not understand clearly enough what you wrote on the paper to be able to implement)

edit: i am told it is here:

I have managed to get a breakout from a flyback powered tesla coil using a standard 555 driver aswell.
Maybe i will try it again with a ZVS circuit.

Danielle

Sun Jun 03 2007, 05:53PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

I saw that error too in the schematics and fixed it I haven't got a chance to test it because of school finals but they will soon be over (5 more days) yes then work work work on everything Tesla. I plan to wrap another secondary this summer for a low frez 50Khz. I did also get some very powerful IGBTs 300A rated they are the 3 pin package but it is four times the size of the TO-247, I only have 4 of these so when I have a stable working H-bridge DRSSTC I will put those in and try it out.

[edit]

I ran my fly back with 10A at 50V driven through my PWM SSTC driver and got a 4" flame from my AC fly back, I modified a DC and cut out the HV diodes.

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