MOT info

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Rich Simpson <richcreations@xxxxxxxxx>

Hi, I am new to the list, and was wondering if anyone knows which is the 
best way to build MOT stacks of more then 4 MOTS? I am interested in 
building a 6 or 8 MOT power transformer. also what would be the best way to 
ballast such a supply (inductive, or capacitive), power is not an issue, I 
can draw 240v/60a/60hz with out a problem, but would rather not have the 
meter spin like that...

I have seen a few different ways on the net, but did not know which was best.

-Rich
On Dec 20, 2004, at 9:58 PM, Tesla list wrote:

> Original poster: "Barton B. Anderson" <tesla111@xxxxxxxxxxxxx>
>
> Hi Chris,
>
> Your problem is likely tuning and coupling. There is more info needed to 
> be completely accurate. I guessed at wire size to be #24. With toroid, the 
> resonator should tune at 335 kHz. Thus, with your .058uF cap size, you 
> need 3.9uH of primary. I couldn't model your complete primary since it is 
> part helical and flat. I did note that of you have 4 turns of helical and 
> this coil would tune in at 4.7 turns, so it should tune in somewhere 
> around the first "flat" turn which I believe is turn 5.
>
> You don't mention the sec height in relation to the primary. So, "if" the 
> bottom winding were even with the first bottom turn of the helical 
> secondary, your coupling would be high, even with only 4.7 helical turns 
> (0.163). Simply raising the secondary 1" will drop this value to 0.125 (as 
> a reference since I don't know actual positions). Sparks breaking out of 
> the center of the secondary indicate the voltage at the breakout position 
> (be it a voltage node or whatever) is too high. Because of it's position, 
> I suspect your out of tune.
>
> I recommend positioning the secondary so the bottom turn is center to the 
> helical and tune the coil at that position. Depending on your actual cap 
> value, the inductance needed may be slightly more or less than 4.7 turns. 
> You can adjust coupling higher for performance improvement after you are 
> sure you are tuned in.
>
> Take care,
> Bart B.
>
> Tesla list wrote:
>
> > Original poster: "Christopher" <cpfortun@xxxxxxxxxx>
> >
> > Hi,
> >
> > I'm writing in regards to a new coil I recently constructed. The specs 
> > are as follows : 9kv franceformer....180mA, SRSG, a total of 24 
> > caps.....8 seriesed 3 legs paralled.. (.15MFD at 2000V each) making for a 
> > total of .058MFD, the primary coil consists of 11 turns......the first 
> > four turns are vertical and the other seven are horizontal.....I am using 
> > 1/4" soft copper tubing "OD" and the spacing between the turns is 1/4", 
> > the secondary is 3" "OD" with a total height of 24 1/2" with the magnet 
> > wire wrap length meausuring 22 3/4"........on top of the secondary is a 
> > spacer which holds the toroid a total of 3 1/2" above the secondary, the 
> > toroid measures 19 1/2" by 4". The electrical connections are as follows 
> > : xfmr is in parallel with the caps, on end of the caps is connected 
> > straight into the primary coil, the other end of the caps is connected to 
> > the spark gap (one side of the spark gap), the other side of the spark 
> > gap is used for the tapping point of the primary coil, (The safety gap, 
> > secondary coil, and strike rail are connected together as one source 
> > going to RF ground). If there may be any questions that need further 
> > explaination in regards to the mechanical or electrical setup let me know.
> > Moving on to my troubles.......when I initially constructed my coil I 
> > allowed for a 5" inside diameter between my secondary and 
> > primary........which left a total of 1" spacing between these two. This 
> > wasn't enough because I was getting sparks from my primary to my 
> > secondary on the vertical turns. So I redid my primary and made for a 6" 
> > inside diameter needless to say this fixed the problem and decreased the 
> > tapping point. The problem now is that my streamers are extremely short, 
> > maybe 10 inches, and I am getting sparks that start about the middle of 
> > my secondary which strike down to my primary. The tapping point has no 
> > effect on the size of the streamers no matter where I tap it, they are 
> > the same l ength. I tried raising the secondary gradually but has no 
> > effect on eliminating the sparks from the secondary to the primary.....I 
> > either get sparks or nothing at all. The spark gap is set up as 4 
> > stationary electrodes and 1 rotating electrode. I am also using a variac 
> > with this system. After the spark gap has been turned on and operated up 
> > to full speed, I slowly turn up the variac from 0 V to 120 V, this is the 
> > reaction of the spark gap....all four will fire, then two will fire and 
> > them the other two will fire almost instantaneously, then only two of the 
> > electrodes will fire until I reach 80 volts and then all four will kick 
> > in again and stay on up to 120 volts. Does this sound pretty normal for 
> > the operation of it ? Anyhow that's enough for now.
> > Any feedback in regards to the sparks from the secondary to the primary 
> > and just the overall setup and operation of this unit will be greatly 
> > appreciated :)
> > Thanks,
> > Chris F.
> > <mailto:cpfortun@xxxxxxxxxx>cpfortu n@xxxxxxxxxx