Question on voltage of electrolytic cap

No - if there's space for it. They're bigger, like for like.

Thank you, Dave. :)

Yeah, the 50V is more than twice the size of the 35V, and may not fit. But it's all I seem to be able to find for that value and high temp.

'preciate it.

Dave

"Dave" wrote in news:etedncXr0t8n3WrVnZ2dnUVZ snipped-for-privacy@posted.internetamerica:

nothing,if the physical size of the new cap fits in the space of the old cap. Mind your ESR requirements. Switcher power supplies need low-ESR caps.

In theory, if the cap has a voltage rating much higher than the actual circuit voltage (say, a 100V cap in a 50V DC circuit), the capacitor is more likely to deform.

That's the theory. I've never seen any systematic study of it. Anyone know "fer shure"?

Thank you, Jim. Any ideas on how I can determine what the ESR of a cap is? Seriously, I know this matters, but have no idea as to how to apply the question. Maybe Google... Just a thought.

'preciate it.

dave

"Dave" wrote in news:PZGdnT5X-4P4m2XVnZ2dnUVZ snipped-for-privacy@posted.internetamerica:

Dick Smith Electronics used to sell an inexpensive ESR meter kit(I have one,love it),Anatek may still carry them. around $50 USD.

you could probably look up the manufacturer's specs on their website.

Why, *thank you*. Will check out said kit, and Anatek as well. Much appreciated.

Dave

Yes, the 100 volt electrolytic will eventually become a 50 volt electrolytic (or whatever voltage is actually impressed on it). The aluminum oxide film that is the actual dielectric of the capacitor will hydrolyze eventually dissolving the oxide back into the electrolyte. This is why relatively new electrolytic capacitors sometimes need to be reformed. In most cases, this is seen as an elevated leakage current in the first few hours of operation. In the old days when vacuum tube rectifiers were in vogue, power supply electrolytics would be subjected to a higher voltage than their normal operating voltage until all the tubes were "warmed up". This is why high voltage electrolytics often had a surge voltage rating high enough to prevent breakdown during those few seconds that the supply was not providing current.

I wrote a number of posts about 9 to 10 years ago on electrolytic capacitors and their chemistry. Most of these can be found archived at

Dr. Barry L. Ornitz WA4VZQ