[sdiy] capacitor voltage ratings

[Bob Weigel]

You can always sub up in voltage, but you might run into size 
constraints.  And you should also consider the esr ratings if that's a 
factor.  Some caps are lower equivelent series resistance. And then 
there's temp rating in some apps. Particularly if it's setting right by 
a heat sink or power resistor it's wise to get a higher heat rated one.  
Other times you can actually arrange things safely so that the capacitor 
is away from the reisistor or whatever too by insulating leads and 
tacking the cap onto another part with glue.  Hot caps don't tend to 
last as long.
     Anyway pricing varies because some types are just higher volume and 
thus the seller gets a better deal on them.  People tend to use a lot of 
10uF for instance but not as many 15uF just because a lot of designs 
specify 10 in apps where it doesn't really matter much..like where you 
just need some kind of local filter cap that is bigger than 1uF.  So 
they picked the easiest to get one and since we count in 10's...that 
wound up being the one that everyone had I guess in quantity. -Bob

Rafael_Cohen at prusec.com wrote:

>Hey everyone,
>Yet another newbie question here.
>I am curious about the voltage ratings on capacitors.  I was buying some
>from www.Jameco.com earlier today and I was trying to figure out the
>dirrefences in price and the differences between the different products....
>If I have a previous circuit that I am trying to copy and the old one uses
>100uF caps at 16V can I substitute 25V?  50V?  Why are some cheaper than
>others?
>
>Also, in the CGS parts lists (soon to build my Steiner VCF), some of the
>modules list caps at a particular voltage.  If I am substituting, is it
>irrelevant as long as it is a higher value than the given specifications?
>
>Thanks for any info...
>
>
>Rafael
>
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