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Registered Member #810
Joined: Wed May 30 2007, 05:23PM
Location: Quincy MA
Posts: 17
Certainly would like to avoid building a massive array of diodes for this.... Already have a crick in my neck from building the SISGs....;- )
Have a matched set of MOTs so was thinking of going antiparallel with a third MOT for ballast... MOTs are 1200W so was assuming I was looking at somewhere around a 10amp draw... Is my assumption right and can these handle the current?
Also have 4 SISG boards built up with an assumption that I was working up to 12KV with the NST and with the MOTs I was thinking of starting with 2 (4x900x2=7200V) with an assumption that I will be looking at roughly 8KV out (2kv/mot x 2 doubled)... Does this sound about right?
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Well, just because the MOT is rated at 1200 watts does not mean they will not draw much much more, and it probably will in tesla coil duty, as the capacitor keeps a constant load on the capacitor and when it is fully charged and stops drawing s much current, then the spark gap fires, shorting the MOT for a short time. Just ask Dr. Kilovolt, he knows about how much MOTs can draw( i do believe it was him...).
Since you have some MOTs why don't you go for a single MOT tesla coil? The capacitance would have to be high, i think around 200-300nf but the voltage would be low, and i find it easier to get high capacitance and lower voltage than high voltage and lower capacitance. Also, at 2kvac capacitors will not die as quick because there is not much corona losses at 2kv. Of course you would use less capacitors per string for higher capacitance.
The sisg will allow lower voltage firing allowing for a single mot to be used without doubler. I am still thinking about making a sisg and i think single mot would be the way to go, because MOTs are cheaper(WAYYYYY cheaper) than nst, they can handle more wattage than many nst's, they will probably not die as easily, and they are lighter. Also, you would need alot less sisg modules for that low of voltage(higher current rating though) which would REALLY save money, time, and space.
It would only take two 900volt sisg modules for a single mot and it would fire at 1800 volts which is good considering that would allow for less stress on the capacitors and mot(on a static gap nst coil you do not want the gap as wide as it can possibly fire at to allow for more headroom for the nst and capacitors) and it would require slightly more capacitance to keep a good 120 hertz firing speed.
I actually know of a site that might really help you in your decision to make either a single or double MOT power supply:
I would still go with single to keep parts count down and keep it simple. Also for lower power levels as i only have 15 amp breakers..
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Converting a SGTC to SISG
