Re: [TCML] At a loss. No light on second coil

[Scott Bogard <sdbogard@xxxxxxxxx>]

Hi Andrew,
     I wouldn't waste my time with the capacitors just yet, and here is
why...  MOT coils work great without them (I don't use them), so by adding
them you are not figuring out why the coil is not working, you are just
changing a variable which is likely not the problem (spark gap is firing so
power supply IS working to one extent or another) and introducing more
possible causes of failure.  If I had to guess I would say you are majorly
power arcing, I had the exact same problem with my first 4 MOT stack.  I
suspect you are also badly out of tune, both these things will cause
the symptoms you are experiencing, assuming you don't have a secondary
short or carbon trail, which seems to not be the case according to your
inspection.  As for your secondary being too small, I wouldn't fuss about
that too much, yeah your coil is a bit small for your power level, but it
is easy to dial back power until tuning is fixed.  If it were me, I would
do the "put a pole next to the top load and look for sparks" thing until
you get it tuned.  Don't be afraid of sparks spontaneously forming
regardless of power level, it isn't going to spontaneously start working
fantastic and kill you (unless your spark gap is terrible and not
quenched.)  I would also personally rebuild your rotary, that will rule out
power arcing (if the arc in the gap stretches, it is power arcing.)  It is
also possible a MMC cap shorted, and it is now impossible to tune in your
configuration, I've used a lot of homemade caps early on and that was
sometimes a problem.  What are your cap specks again?  Remember as your
voltage goes down, you need a bigger cap to maintain a healthy power
transfer rate; if your cap is too small, it will be impossible to tune from
a power draw standpoint, even if it is "in resonance."  It is also possible
one leg of your MOT stack is unhooked, but you said you drew sparks from
it, so I don't believe that to be the case this time.  Anyway when push
comes to shove, if you want to rule out the power supply, don't throw more
parts at it, take away parts, fall back to 2 MOTs, this would be more
prudent troubleshooting practice.  Once you are running a 2 pack, go from
there with tuning, and once it purrs, reintroduce the other MOTs, and feel
the power!  Just my recommendation, I wouldn't want you to spend 2 months
trying to figure it out like I did...

Scott Bogard.


On Tue, Mar 26, 2013 at 1:51 PM, Andrew Webster <andrew600rr@xxxxxxxxx>wrote:

> Thank you,
>
> I think that is my next step. Ill start with 5 MOCs per side in
> between the first and second MOTs on each leg (AKA Greg from Hot
> Streamer) and then go from there. I guess I was more of less wondering
> if it was possible to overwhelm your coil if the power was too high?
>
> No carbon
> Great grounding (8' copper rod buried straight down in semi-sandy moist
> soil)
> Primary, secondary, toroid were pulled from a working coil. Just much
> less power.
> Cap and gap are firing great. You cannot miss the sound of the gap
> snapping that hard.
>
> I have even run it in total darkness to see if I was arcing somewhere
> and didn't notice. Unless its on the back side somewhere I cannot find
> anything. Which is why I am so confused as to how I screwed this up so
> bad.
>
> My other thought was to lower the capacitance to see if it broadens
> the tuning. Maybe its just too tight?
>
> Ill setup with the MOCs and report back. Most likely this weekend. If
> anyone else has any ideas I would love to hear them.
>
> Thanks again all, it will be a great day to see this come to life.
>
> On Tue, Mar 26, 2013 at 1:07 PM, Atomic <atomicrox@xxxxxxxxx> wrote:
> > I'm no expert but I've seen MOT coils using MOCs as capacitive ballasts
> in
> > series with the HV side of the MOTs. Might want to try that out..
> >
> > On Tue, Mar 26, 2013 at 1:37 AM, Brandon Hendershot <
> > brandonhendershot@xxxxxxxxx> wrote:
> >
> >> I'll second that. If you're confident in your numbers and you've got
> that
> >> much raw power pumping into the coil without any output, then it seems
> to
> >> me like a power arc. Nice catch David.
> >>
> >> Brandon H.
> >>
> >> On Mar 25, 2013 5:51 PM, "David Dean" <deano@xxxxxxxxxxxxxxxx> wrote:
> >> >
> >> > On Monday, March 25, 2013 04:26:16 PM Andrew Webster wrote:
> >> > > So I built a 4 pack MOT
> >> > > stack and wired for 240. Center grounded and under oil. There is no
> >> > > ballast on this and I can draw some nasty sparks off of this.
> >> >
> >> > So your gap is not quenching, hence no sparks.
> >> >
> >> > >I am using a static sucker gap as I melted the brass off of the ARSG
> >> > >in seconds. The static gap is holding up better to the heat until I
> >> > >can get some tungsten.
> >> >
> >> > I probably should not say this, but:
> >> > You might try a 100 foot extension cord to act as a "resistive
> ballast"
> >> > keep run time short, as the extension cord will heat up, could melt,
> >> could start
> >> > a fire. Only a test :-D
> >> >
> >> > Or better, do a real ballast.
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