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Re: Variac setting (Was Rd: Rotaty popping)
In a message dated 4/28/00 11:01:45 PM Pacific Daylight Time,
tesla-at-pupman-dot-com writes:
>
> Bart,
>
> I measured my ballast variac last night. It is made by Luxtrol, says
Light
> Control on it, max 41.6 amps (says to fuse it at 50 amps). It also says
> taper wound - which is odd, I don't see any taper to the core or the
> windings. It is however very non-linear. The maximum inductance is 54
mh.
>
> The point where I had it set was only 5 mh. Now I find it really odd that
> trying different settings (probably over a range of 3 mh to 30 mh)
appeared
> to show no difference in coil performance. There is something to learn
here
>
> but it isn't real obvious to me. It seems that some inductance is
required
> but the actual amount used is not critical - and why do welders seem to
> cause
> problems that variacs don't? I even measured the inductance of the welder
> that I originally used and remember it to be in this range.
>
> Ed Sonderman
>
Ed, Bart,
One thing I have noticed is that coils using async gaps are able to
run over a much wider range of ballast inductances than low bps
sync gap coils. In the higher bps async coils, the ballast inductance
can be used to vary the power output of the coil. Low inductance
gives longer sparks, higher inductance gives shorter sparks. In the
low bps sync gap TC, only a certain inductance setting will give long
sparks. Inductance settings that are higher or lower will reduce the
spark output. I can only assume that it's all a matter of resonant
charging or inductive kick charging, and how it behaves at differnt
break-rates, and whether it's sync or async.
It is interesting that you have the variac inductance set at 5mH, since I
believe you said the welder inductance may have gone only down to
10mH, so that is a differnce there. Of course you also said above
that the inductance setting doesn't make much difference at all now
to the coil's performance, and that is interesting indeed.
Cheers,
John Freau