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Re: Tesla Software
Hi Graham,
> Thanks Malcolm, although I am having some trouble with these
> figures. I do not doubt the value of 100nF but have trouble
> replicating it. Using the traditional formula of C= KA/d K =
> Dielectric Const (2.28 for LDPE) A = overlap area in inches d =
> dielectric thikness in inches (answer in pF)
> gives a value of 238nF for a flat cap and roughly double that for
> a rolled cap. I have been rather short of sleep lately and may be
> staring the obvious in the face. Please show me what it is.
Perhaps some air inside may account for it although they are rather
solid once rolled. I do know from my plate cap that its capacitance
went down by a third when I loosened it to allow oil to penetrate and
then went back up to nearly the original value once the oil was in
there. Beyond that, I'm not sure. In fact the cap consists of 12
plates (6 per actual plate) each a metre long. This greatly
facilitated rolling. I suppose there's an element of suck and see in
all this. I'm sure Richard Hull would concur. As I say, repeatability
was good, and the design is predictably scalable to other values
e.g. 50nF.
Malcolm