Polymer cap ratings

[Lance Thornton]

Hi all,

I hope this is not a double posting, but I would like to know the method of replacing an aqueous cap with a polymer one. Specifically, are there any formulas that would help me buy or size the right one if I'm replacing a 1000uf@6.3 volts, etc. I assume that the diameter must be equal or smaller, depending on spacing. I also wonder about the heat issues with polymer capacitors rather than electrolytic. My apologies if this question has already been posted.

Thanks all,

Lance

[ratdude747]

Re: Polymer cap ratings

it can be hit and miss.

the two values you need to keep in mind are the voltage and esr:

voltage- lowest voltage that is in spec with the circuit (measure with a multimeter, 6.3v caps often get less than 4v going to them)

capacitance- generally half the 'lytic value, but:

esr- same or lower, which is generally half the capacitance.