i just wanted to ask?
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does any one use multilayer glass dielectric capacitors for recapping motherboards?
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Re: does any one use multilayer glass dielectric capacitors for recapping motherboard
I don't see anything larger than 1200pF in an appnote i found. They also are pretty big. Good luck fitting enough of them on a typical mobo.Originally posted by PeteS in CARemember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
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Re: does any one use multilayer glass dielectric capacitors for recapping motherboard
Using glass as a dielectric produces a cap that is maximized for no or very low leakage. Glass caps can stay charged indefinitely. One example of a glass cap is the standard television tube which has 2 layers of conductive carbon (aquadag) separated by the crt glass envelope. That cap is part of the high voltage filter system for the crt anode. A few pf at 50 KV or more. Tradeoff: using glass for a dielectric is only practical for very small capacitance values and definitely not in the microfarad range. Once in a while you see glass caps used in precision timing circuits, but these have largely been replaced by digital and software based designs. To get an idea of practical sizes of various caps, have a look at a chart of dialectric values - that will tell you what is practical in terms of physical size. Ever seen a 1 microfarad polymer (non-electrolytic) cap? Huge.Is it plugged in?
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Re: does any one use multilayer glass dielectric capacitors for recapping motherboard
Yup, no advantage in using low-K materials like glass or porcelain, which are optimized for low loss in the microwave region. However, X5R ceramic is now available in reasonably large values (4.7uF..22uF) in very small sizes (0603) for motherboard and general digital bypassing, and I've used these successfully for mobo upgrades. The only minor drawback is that the ESR is not very low (4.7uF measured 0.4 ohm), but it still works well especially when several are used in parallel.
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Re: does any one use multilayer glass dielectric capacitors for recapping motherboard
Originally posted by Uniballer View PostHow big would a 820uF 6.3V capacitor be? What kind of ESR would you get?
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