Electrolytic caps are normally for high capacitance values as there are 
no other way of achieving so high values with any other type of 
capacitor (AFAIK)

But they have relativelly large series resistance and also, at higher 
frequencies, a high inductive load (due to its own construction form), 
so other types of capacitors are used for lower capacitance levels

AFAIK, ceramic capacitors (as they're really flat) are the best in terms 
of series resistance and inductive component of the total impedance.

Insulation voltages are also an issue. Best ones here are polyester or 
polypropilene.

Hope this helps to get you started
Francisco


Mcgee, Mark wrote:

>I'm a relative electronics newbie (A-Level, 15 years ago, not much since)..
>
>..I was wondering why you would choose one type of capacitor over another in
>given applications.
>
>I notice that the example cct on a datasheet for the LM317LZ vreg specifies
>0.1uF electrolytic, but has onother in a different part of the circuit that
>isn't electrolytic.  Why might that be?
>
>Regards,
>Mark
>
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