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Re: capacitor charge rate/power
Tesla list wrote:
> Original poster: "Pholp Smiff" <kawanze-at-hotmail-dot-com>
> can anyone give me a formula as to how long it takes to charge a capacitor
> depending on size and power? i.e.: using a 12kv-at-60mA transformer, how long
> would it take to charge a .1mF capacitor?
CP charge time in an AC circuit is transfomer impedence x Cp x 5.
Z x Cp x 5 = 200,000 x 0.1uF x 5 = 100ms for "full" charge.
> Can someone tell me and show me
> the math behind it? And how much power is actually stored and let out in a
The term is "energy" stored in the cap rated in joules.
energy in cap = 1/2 x Cp x Vp^2 = .5 x .1uF x 12kv^2 = 7.2 joules
BTW, a .1uF cap is pretty big for a 60mA transformer. If you set a gap to fire
once every half cycle (120 bps), then you would only charge this cap to 20%
(3.3kv) and the energy stored would be way down to 0.58 joules. Obvisously, the
discharge rate would be set much less than 120 bps to charge the cap to a
decent voltage. A more realistic cap size would be .01 or .02uF for the
transformer (or you could build a big coil and use a big transformer for this
> Also i'd like to know how to determing the size of a bleeder
> resistor for capacitors.
Terry covered that in his post.
Hopefully this helps. If anythings wrong there, hopefully someone will correct