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Re: Sparklength inquiry
> Original Poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> >> Bart, Greg -
> >>
> >> I agree the equation (Vs/1000/65)^1.43 is not correct. It should
> >> be(Vs/65000)^1.43 where Vs is the secondary volts or
> >> (KVs/65)^1.43 where KVs is the secondary kilovolts. -JHC
> >
> >The revised equation is also incomplete, since it still does not
> >account for the effects of BPS on spark length, which are
> >significant. -GL
> >
> >> To my knowledge this is the best equation presently available for
> >> TCspark length. It will probably change when more accurate data
> >> from coilers becomes available. It appears to be working well at
> >> present. -JHC
> >
> >Except that the equation blows up completely if the break rate is
> >altered. This should be fixed. -GL
>
> Greg -
>
> Not true. Note that the Vs is a function of BPS in the equation
> Vs = sqrt(2 watts/(Cs BPS))
> The spark lengths are for controlled sparks. Streamer sparks can be
> 2 to 3 times longer depending on the guestimate of the coiler.
>
> John Couture
Again, the algebra is lacking here. In the above equation,
Vs would only be a function of BPS if the quantity "watts"
was a constant. But since watts is an inverse function of
BPS, the above equation simply reduces down to Vs = SQRT(2Es/Cs).
At this point, I should once again offer the following test data
from my old coil:
Primary capacitor is 0.225uF, Vpri = 26kV.
The Vpri is *not* adjustable in this design, which means that Ep, Es
and ultimately Vs are independent of the break rate.
At a BPS of 1 and a Vpri of 26kv, sparks are about 2.5 ft long.
At a BPS of 80 and a Vpri of 26kv, sparks are about 4.0 ft long.
At a BPS of 350 and a Vpri of 26kv, sparks are about 25. ft long.
Since I have an oscilloscope and a HV probe, I am able to determine
that the maximum jitter on the 26kV value is less than 2kV at any
break rate. With a current probe, I can also determine that the
peak secondary base current of 27A has a jitter of less than 3A,
confirming that Es does not vary considerably either.
I am quite convinced that Vs is *not* an inverse function of BPS.
(unless the charging circuit is broken)
But you might not believe my measurements. So I should ask if
anyone else on the List has data from *actual operating coils*
which might indicate whether Vs, and therefore Vpri, varies as
an inverse function of BPS.
Comments?
--
-GL
www.lod-dot-org