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Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Dr. Monsterarc wrote ...
MadsKaizer wrote ...
Calculating the resonating frequency is like a standard LC circuit? As I am currently not home I cant measure the inductance of the secondary and give it a go.
Resonant frequency is determined by capacitance and leakage inductance of your MOT. Short the MOT primary and then measure the secondary inductance.
unballasted it draws around 1250W, with another as ballast I will draw about twice as much right? and my only single phased circuit breaker for my appartment is at 10A / 230Vac. I would have to remove my oven to access the 3phased 16A isntallation if I want more :(
thanks about the measurement, I forgot to short the primary so the value was off the meter, turns out i accidently hit the sweet spot I guess, with a secondary inductance of 5.55H and 1.81uF capacitor bank its freq. is 50Hz, same as the primary.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
MadsKaizer wrote ...
unballasted it draws around 1250W, with another as ballast I will draw about twice as much right? and my only single phased circuit breaker for my appartment is at 10A / 230Vac. I would have to remove my oven to access the 3phased 16A isntallation if I want more :(
Maybe it will draw a bit more, as it will probably drift off the resonance for a little. But this little "slip" will make for more stable arcs.
Fraggle wrote ...
It will draw LESS current with the ballast.
This is my first post...Hello!
Hi Fraggle and welcome to 4hv You may not be right as this resonant circuit behaves differently than just "plain" transformer. If in proper resonance, it will draw little current with output shorted and the current will go up as you draw out the arc.
Registered Member #964
Joined: Wed Aug 22 2007, 12:39AM
Location: Stockton, CA
Posts: 134
Weee! Finaly got my 2-MOC setup working. Turns out that second MOT for ballast wasn't needed. 6" arcs are good enough for now I might be getting another microwave off of freecycle, so I'll have even more stuff to work with. Video coming soon (found out my camera has a short video-clip option. Too bad there's no sound, the BZZZZT sounds sooo cool..
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Spedy wrote ...
Weee! Finaly got my 2-MOC setup working. Turns out that second MOT for ballast wasn't needed. 6" arcs are good enough for now I might be getting another microwave off of freecycle, so I'll have even more stuff to work with. Video coming soon (found out my camera has a short video-clip option. Too bad there's no sound, the BZZZZT sounds sooo cool..
I don't think 6" is that much... do you have another capacitor? If so connect it in parallel, it should increase the arc length considerably, for some lower leakage transformers it is not uncommon it can double.
Registered Member #1526
Joined: Mon Jun 09 2008, 12:56AM
Location: UK
Posts: 216
I agree, you ought to get longer arcs than that. I found that some ballast stopped the arcs blowing out so quickly and stopped my fuse blowing, this is why I suspect lower current draw. I think pulling out some shunts from the transformer might lower the inductance a bit and help you tune in but I`ve not tried that.
Registered Member #964
Joined: Wed Aug 22 2007, 12:39AM
Location: Stockton, CA
Posts: 134
I'm just guessing, it could be up to 10-12". I'll hold it next to a ruler on the next run. Sorry, the two MOCS are all I have. They're in parallel w/ each other and in series with the MOT'S output. I might try prying out one of the shunt layers later. Edit: aww, the freecycle microwave was taken. ahh well..
Edit 2: Wait, how exactly do you remove the shunts? I've used a screwdriver to pound one out of the core most of the way, but now it won't budge any more... Also, it seems pretty much impossible to remove individual shunt pieces. I assume you meant the groups on either side of the core center.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Spedy wrote ...
Edit 2: Wait, how exactly do you remove the shunts? I've used a screwdriver to pound one out of the core most of the way, but now it won't budge any more... Also, it seems pretty much impossible to remove individual shunt pieces. I assume you meant the groups on either side of the core center.
Do NOT remove the shunts. You want to add inductance, not lower it.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Spedy wrote ...
Arg! mixed signals >.< Ok then, how do I ADD inductance? (goes to pound shunt back in)
Well if it works well with the shunts in, leave it alone, otherwise you can add inductance by a ballast (sec. shorted) MOT.
How do you know when you need more inductance? If the inductance is too low, the arcs will not be stable and make funny noises before they go out. Also quickly drawn arcs will be much longer than slowly drawn ones.
On the other hand if you have too much inductance, the resonant rise will not be as apparent and the arcs will be smaller no matter what you do (and they won't make any funny noises).
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Resonant MOT arcs
