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Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Oh, hehe maybe i should have looked better before making assumptions. I wish i could donate a MOT for this project, but the shipping would be just horrible. I can get good MOTs quite often. I do not have a spare big one right now(depends on what is considered big), but i am sure it wouldn't be too hard to get one. Also, i have no way of knowing voltage. I could look at the capacitor, but that means nothing, they could be over rated for all i know.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Arcstarter wrote ...
Oh, hehe maybe i should have looked better before making assumptions. I wish i could donate a MOT for this project, but the shipping would be just horrible. I can get good MOTs quite often. I do not have a spare big one right now(depends on what is considered big), but i am sure it wouldn't be too hard to get one. Also, i have no way of knowing voltage. I could look at the capacitor, but that means nothing, they could be over rated for all i know.
Afaik the caps almost always have 2100VAC on them, even when they happily survive 4kVac. The MOTs don't vary that much, almost all are in the 2000-2200V range.
Registered Member #229
Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506
This is not quite difficult. Feed your MOT with a known voltage (let say 10 V) and measure the secondary output. Or connect it to the mains in reverse (mains on the secondary) and measure the low voltage output from the primary. You will know the transformation coeficient K = N2/N1 = U2/U1, so multiplying the mains voltage with K you would have an oppinion about the high voltage output.
If I will get a bigger MOT the transplant is easy.
Registered Member #1732
Joined: Thu Oct 02 2008, 02:34PM
Location: Huntsville, AL
Posts: 112
vasil wrote ...
The feedback is tapable. I tried differente settings, and the best is 21 turns:
What I would need would be a 2400 V MOT...but I am building with what I have in my hands. Big MOTs are rarities here.
Interesting feedback coil. I like how you have variable taps on it.
Have you considered running two series-wired then level-shifted MOTs? I'm not sure what kind of voltage the tube you're using can take, but this is the configuration I use with my tube coil. Under load the the transformers in my setup do not deliver enough voltage to damage the plate, but they certainly deliver more voltage than a single level-shifted MOT.
Nice job on the coil. It's harder when all the components are visible, as you have to make the wiring much neater to keep the coil looking respectable. For my VTTC I put it in a box, so all the wiring is hidden except for the two leads to the primary, and the tube.
Registered Member #229
Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506
Thanx Phillip
I have only one little MOT. I had a bigger one on my previous PROJECT You can see it HERE , biger core and plastic insulated coils, bigger sparks also.
I will hunt some new MOTs (I need two identical to parallel them in my next GU5B VTTC), maibe I will have luck. If one more MOT comes in my hand I can series them. :)
Registered Member #1732
Joined: Thu Oct 02 2008, 02:34PM
Location: Huntsville, AL
Posts: 112
vasil wrote ...
Thanx Phillip
I have only one little MOT. I had a bigger one on my previous PROJECT You can see it HERE , biger core and plastic insulated coils, bigger sparks also.
I will hunt some new MOTs (I need two identical to parallel them in my next GU5B VTTC), maibe I will have luck. If one more MOT comes in my hand I can series them. :)
Well you could always steal from another project At any rate it looks like the tube you're using wouldn't take the kind of voltage that an 833 will take.
I'm not sure if I see the benefit of paralleling MOTs. They can usually deliver plenty of power on their own. Doubling them you get nearly twice the voltage which means four times the energy stored in the tank cap
The plate voltage is low enough for a single MOT and a single doubler and I was afraid to not be able to get all the current needed only with a single MOT. I just invented some complicated circuit with a lot of diodes, but the advice from the forum was jut to parallel MOTs to get it better....it will be easier for me too.
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Tube coil project
At any rate it looks like the tube you're using wouldn't take the kind of voltage that an 833 will take. 
