On Thu, Mar 10, 2011 at 4:47 PM, IVP <joecolquitt@clear.net.nz> wrote:

> > How would you define large and small? Is 10uF large?
>
> 10uF would be a small electrolytic, a large non-polarised
>
> A leakage figure for a general purpose aluminium electrolytic
> < 1000uF might be something like 0.01CV or 3uA, whichever
> is greater
>
> Larger values, > 1000uF, might be 3CV, +100uA if > 100V,
> which can be several mA
>
> so you work out from that what the leakage will be for the voltage
> and uF you use and whether it's significant. For example a high
> value resistor, eg several Meg, and a cap that leaks a few uA is
> going to be a terrible RC combination, because the small current
> available through the resistor is leaking away through the cap, not
> charging it
>
> The above applies mostly to aluminium electrolytics. Ceramic,
> plastic [and tantalum, bearing in mind uF tolerance] caps are
> better suited for timing


Thanks for the info. For my bandpass filter, I used 10uF bipolar aluminum
electrolytic caps and 47K and 120 resistor values. I think those should be
reasonable values.
--=20
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