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Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Well, i made it before and it did not work right. I found out that is was becasue i was using a dang smps. Well, i decided to remake it so that it would be easy to replace burnt mosfets. I used 2 screw terminal things to attach to the mofets, for easy replacing and i just soldered everything straight to them. I used 1 watt 12 volt zeners, 2 uf4007 as fast diodes, .68uf cde cap for tank cap, one of ultra7's big Dale resistors(tapped the resistor for 500ohms for each side), 2 1/4 watt 10kohm resistors, and 2 irfp250 mosfets. I will take a video in awhile of it. At 25 volts it pulls 13 amps, which is 325 watts, and i just recently upgraded to my rewound mot, for 35 volts dc output, and it pulls about 17 amps(18 max), which is 595 watts! At 25 volts and 325 watts i ran it continuous for like 30 minutes with no heating of anything but the bridge rectifier. The power supply is the 800watt(I think) rewound mot, a 4 amp(It actually ran 30 minutes with 13 amps being drawn!) bridge rectifier, and a 15000uf 71 volt smoothing cap. Ima go take a video now :).
Only 125 watts from being as powerful as a 12/60 nst!
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Dr. Kilovolt wrote ...
Arcstarter wrote ...
Only 125 watts from being as powerful as a 12/60 nst!
The NST is actually far behind your driver, as it is 720VA and your driver is 595W. The NST will probably output something between 180-240 watts.
Looking forward to the video :)
How does a 720 watt nst only put out 180-240 watts :P. Yea i know you are talking about reactive power, but i don't understand that type of stuff :(. Have something to do with being dc? Since dc is smoothed, it does not have a point that it goes 'negative' and have the spot that there is no voltage. Also, is it something to do with the frequency? :P Sounds like i made something i don't even fully understand.
Anyway, i just tried downloading my video and it wouldn't... The first video my mom started yelling at me to clean my room :P. The video was 9:55 long. May have something to do with it.
By the way, i recalculated, and the ZVS is pumping about 650 watts into the flyback :O. It was about 18.5 amps max, at 35 volts. The lights dim a bit when i turn on, but of course that is just the inrush current of the MOT.
Off to take a video.
Got the videos. Since i am not using any downloading software, my camera likes to turn off in the middle of downloading, so i had to take three small ones, and they are MOV files, so i cannot connect them all together with windows movie maker, and i tried converting them and that turned out badly :P. There is parts one, two and three, as you could imagine. Part one is the setup(not due to change, just put in a box), second is running with my best flyback, and third is another great dc flyback, that is the same size but pulls about 2 amps less. Here they are, in order:
Oh and by the way, i am now running 800 watts peak, using about 2 more amps and 5 more volts.
Registered Member #1749
Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497
That is beautiful for real that's like mine and nice setup I had to connect my 18v drill battery with a car battery to get 30v incredible arcs that I bet would give u a bad day if something went wrong. I am gonna try to get the secondary out of my MOT tomorrow. If u feel like I am copying u let me know.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
crazy4 wrote ...
That is beautiful for real that's like mine and nice setup I had to connect my 18v drill battery with a car battery to get 30v incredible arcs that I bet would give u a bad day if something went wrong. I am gonna try to get the secondary out of my MOT tomorrow. If u feel like I am copying u let me know.
Haha, no not at all :). By the way, if you do not have enough space to wind the amount you need for the voltage you want, just make it output half the voltage you need, and use a doubler.
I have rewound a few microwave transformers, so if you would like some tips, let me know. I could walk you through the way i did it in like a few sentences :P.
I burnt the flyback out awhile ago. It was not the windings, and it was not over voltage. It was too much current for the diodes, and they must have shorted. Actually it must be the windings too, casue the arcs are smaller and the voltage lower. The core glows with corona near the outside of the transformer. The output wire gets red now, which it never did before, which makes me think it is outputing ac. Cannot think, going to bed, bout to pass out, goodnight, don't let the bedbugs bite your head clean off and s%it in your neck!
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Arcstarter wrote ...
How does a 720 watt nst only put out 180-240 watts :P. Yea i know you are talking about reactive power, but i don't understand that type of stuff :(. Have something to do with being dc? Since dc is smoothed, it does not have a point that it goes 'negative' and have the spot that there is no voltage. Also, is it something to do with the frequency? :P Sounds like i made something i don't even fully understand.
I will try to explain. The NST pulls 720 (or a little bit more) VA with the output shorted. As you draw out the arc, the current will start to fall and the voltage rise. The maximum power point will be reached at 1/2 voltage and 1/2 current, and because P=VI=1/4 so only 25% of the VA rating can be "transformed" into real power which is in Watts.
If your ZVS pulls 600 WATTS, then there's very likely much over 1kVA of reactive power. Probably over 2kVA because the parallel resonant circuit needs a lot of reactive power.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Dr. Kilovolt wrote ...
Arcstarter wrote ...
How does a 720 watt nst only put out 180-240 watts :P. Yea i know you are talking about reactive power, but i don't understand that type of stuff :(. Have something to do with being dc? Since dc is smoothed, it does not have a point that it goes 'negative' and have the spot that there is no voltage. Also, is it something to do with the frequency? :P Sounds like i made something i don't even fully understand.
I will try to explain. The NST pulls 720 (or a little bit more) VA with the output shorted. As you draw out the arc, the current will start to fall and the voltage rise. The maximum power point will be reached at 1/2 voltage and 1/2 current, and because P=VI=1/4 so only 25% of the VA rating can be "transformed" into real power which is in Watts.
If your ZVS pulls 600 WATTS, then there's very likely much over 1kVA of reactive power. Probably over 2kVA because the parallel resonant circuit needs a lot of reactive power.
Well, that sure is helpful Easy to see how that works, still need to learn more about reactive power though :P. Thanks!
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
crazy4 wrote ...
Would it make any difference to make a Faraday cage around the mosfets on my ZVS.
I don't think you would need it. But shorter wires might help. Less resistance=less losses in heat. Also, the more wire the more inductance, which could cause parasitic oscillations, which could heat mosfet and explode it and reduce efficiency. Running about 40 volts in, the 12 gauge wire gets hot! Much hotter than the mosfets though, which is such a great feeling :P. I blew 3 flybacks today :P. One literally blew. It was tiny though, so one could only expect for that to happen. This is why i wear safety glasses when working with ZVS. I will post my new video and some pics later.
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My ZVS flyback driver.
Easy to see how that works, still need to learn more about reactive power though :P. Thanks!
