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My 2nd ZVS (totaly cool)

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Dieu

Mon Dec 22 2008, 10:49AM

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

I have something for U :D
It is my 2nd ZVS, quite big, but totally cold. It may run 30min. on jackob ladder \-/ with no harm :D.
Ok, some fotos ;p
If anyone need help with his not-working ZVS I offert my help.

This triple HV traf. was for lifter, but he don't want to fly :/ he eat to much balsa.
Oki, orginal movie:

Dr. Dark Current

Mon Dec 22 2008, 11:45AM

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

hmm, yes it's cool

but the arc is not really as big as I'm used to see

Dr. H.

Mon Dec 22 2008, 12:21PM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Good day guys

At what distance does it start ? (the arc) and how much can you extend it because ... this seems a bit short for 3 flybacks . What power is that thing sucking ?

Cheers

Dieu

Mon Dec 22 2008, 12:50PM

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

I is becouse I give it ony 100W on 25V, sorry to not have bigger. For something better I preper 150W 50V, but ZVS need to be changed witch some parts.
when it's working on one traf. arcs are much bigger and louder.
Arc here starts at 3cm (30kV), but on jakob ladder it's always shorter. On evry HV gen.

Arcstarter

Mon Dec 22 2008, 07:54PM

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

Hey, that is nice :). Hehe, at first i was like OH MY GOODNESS! THREE PHASE ZVS!

Well, one thing is that if your ZVS is made well, it is going to want MUCH more than 150 watts at 50 volts. Be careful though, 50 volts is a bit high, but my zvs idles at 52 volts. At 24 volts my zvs used 300watts and at 40 it used 600-800 watts. If you used a 50 volt power supply, if the ZVS does not die first, it will probably try to pull something like 20-30 amps, so you would need a transformer capable, as well as mosfets. If you use a 50 volt transformer, it will probably drop to like 20 volts, or maybe lower.

Also, the power supply really needs to be smoothed better. I hear a loud 50hz hum on that video, and the arc should be pretty much silent. So, after rectification of a large high power capable transformer, you should have something like 20,000uf worth of smooting caps. I use a MOT with self-wound secondary(very easy) and it puts out about 52 volts, and it drops to 40 while drawing an arc. It pulls about 18.5 amps while drawing an arc, so that is 740 watts.

Also, those diodes used as a bridge rectifier will not do with higher voltage or current. You need something like an 80 volt bridge rectifier capable of 35 amps. Look for the lowest voltage drop possible. The more voltage drop, the less voltage that reaches the zvs(would only differ maybe a volt or two, most likely less) and the voltage that is dropped is converted into heat.

Dr. Dark Current

Mon Dec 22 2008, 09:07PM

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

I've always had problems with the arc screaming really loud when it got long. Anyone knows a way to fix this other than putting thick spacers in the core? (the screaming stops but then the core and primary get extremely hot)

MRacerxdl

Mon Dec 22 2008, 10:00PM

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

In my 25VDC Mot Power Supply, I was able to push 20A (500W) for my flyback, the arc started over 3cm and goes until 5-6cm ~, so I think too, for three flybacks, that is not much =/
What is the size of your cap?

Arcstarter

Mon Dec 22 2008, 10:01PM

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

Dr. Kilovolt wrote ...

I've always had problems with the arc screaming really loud when it got long. Anyone knows a way to fix this other than putting thick spacers in the core? (the screaming stops but then the core and primary get extremely hot)

Well, if i am correct, which is slightly possible, the screaming occurs with longer spark because as the spark is drawn further, the secondary of the flybacks inductance changes, which would also cause a change in the primary inductance. Well, that of course changes the lc tank circuit(am i missing something here?) which increases frequency i think. So maybe if you change the primary turns or the cap, it will reduce the noise? All i know is that primary inductance has something to do with this, because i was drawing arcs with a transformer, and then i changed from 10ct turns to 12, and it was very loud and screaming. This is the reason that i think that way.

uzzors2k

Mon Dec 22 2008, 11:07PM

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

You've got it right Matthew, but changing the number of turns and modifying the spacer distance has the same effect on inductance. Increasing the frequency to get rid of the noise increases core losses, which Jan wants to avoid.

Jan, maybe you could try putting a separate inductor in parallel with the primary? I was considering it myself for increasing the open circuit parallel resonant frequency of my "big-mofo" xfrmr. It does work, but I'm not sure of the draw-backs and I never tested it with power. The inductor will take some of the primary current and introduce some new losses, but at least it's not losses in the flyback itself.

Dr. Dark Current

Tue Dec 23 2008, 08:42AM

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

Uzzors wrote ...

You've got it right Matthew, but changing the number of turns and modifying the spacer distance has the same effect on inductance. Increasing the frequency to get rid of the noise increases core losses, which Jan wants to avoid.

The screeching sound is low in the audible range, does not have anything to do with the tank resonant frequency. I found that changing the series inductor changes the sound (but of course not the resonant frequency).
Maybe something to do with the LC tank not able to keep high enough "Q" with too much resistive load and not able to "swing back" to zero?

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