Dr.R, all
It's very low because this is only isotropic capacitance. A normal capacitor has two plates and this is similar to a single plate capacitor with the second plate being ambient ground. I would suspect it's only 3-4 pF if even that high.
I think I agree with that.. capacitor plates having a "positive" and "negative" connection.. however, for a primary coil, there is not this arrangement. The "plate" is literaturally connected as a short circuit across the applied voltage... It is not like it is if your cap has 100V between each plate, as there will only be a per turn voltage for a start, which voltage between turns has to be like 75% smaller (4 turns ?) . I think another chap went into this a bit more yesterday...
For a total of 600square inches, that would have to be 300 per sheet which would be 2 plates... 150 for 4 plates... 1.26nF.. so for a normal cap that would be the figure... but as we do not have this connection then I will assume ( just for today ) that there is a 75% capacitance drop per turn as it is in effect shorted out... its probably a lot more than that, though even so the max ballpark figure is going to be something like 600pF ? That's assuming a 1mm gap so if there is going to be even 5mm of gap then the capacitance is probably not even going to be worth considering...
I never use ribbon due to corona. Take a 5 sec B&W 400 ASA exposure and you will see what I mean. I did with earlier coils and the photos almost scaredme. High level of degradation on the sec coil. Perhaps for occassional operation it's ok, but I would not make a commercial unit with sharp edged ribbon. Corona much less for copper tubing.
I know a lot of people say that, its a fair point, though in this case I am using less than 1,000volts so its not much of an issue...
Chris _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla