About capacitors for PC motherboards...

not fit the

or FV25

of each, and

were NOT needed.

given time, and

manufacturers

been running 100%

now. "

It makes them better able to handle voltage spikes, and they handle smaller loads in relation to their maximum.

Mark

not fit the

FV24 or FV25

one of each, and

were NOT needed.

any given time, and

but manufacturers

been running 100%

now. "

What voltage spikes would those be btw ? Read the quoted text.

What's that supposed to mean ?

Graham

Are you really that clueless?

-- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85.

Michael A. Terrell Central Florida

Come on tell me. I want to know what part you think voltage rating plays in lifetime for electrolytic caps.

Graham

Where do you get this rule of thumb from ? I suspect it's a myth.

Graham

One rule of thumb is "proportionally", up to 2:1 derating. So, you'll get 58% more lifetime out of a 10V elect. cap operated at 5V compared to a 6.3V cap, all other things being equal. Whether the formula holds for the low-Z caps, I don't know.

Best regards, Spehro Pefhany

Check electrolytic capacitor manufacturer's data.

Here, for example, is Cornell Dublier which gives a somewhat more complex formula:

k = 4.3 - 3.3 * Va/Vr , which works out to 1.0 at Va = Vr, and 2.65 at Va = Vr/2, and 1.68 at Va = 5/6.3, which would yield 63% more life for a 10V cap compared to a 6.3V cap, not so far from the +58% calculated by my rule of thumb.

Of course temperature is a greater factor in the lifetime, but there is often little you can do about that.

Best regards, Spehro Pefhany

I very much have done !

At what ripple current ?

Don't give Michael too many clues. I'm waiting for his reply.

Graham

You won't get it. I replied directly to Spehro, and you are being plonked on this newsgroup, too.

By you ? I'm devatated. FYI applied voltage is a relatively insignificant factor in capacitor lifetime.

So, what really causes electrolytic caps to 'wear out' ? I know. Do you ?

Graham

Seems like that would depend on the designer and tech in question... there are plenty of freshly-minted EEs out there today who couldn't bias a transistor to save their lives... although if that isn't their job, I suppose it doesn't really matter...

Aren't they the EEs who end up in sales? ;-)

I was surprised to find that these days it's generally *required* to have a EE degree if you want to sell scopes, etc. for Agilent. I honestly think this is more a reflection of how dumbed-down the average EE curriculum is today rather than how "sophisticated" modern test equipment has become.

More than likely I reckon.

Graham

Yes, that's sad, and it seems the less a new engineer knows, the more they brag about their degrees. The older engineers didn't even have their diplomas on the wall, but some of the younger ones had copies on every wall of their cubical to try to impress everyone else. The real engineer could look at a schematics and the notes, make a decision and have the ECO done before my modifications made it through test. The kids took months.

I was amazed that I knew more about a digital H-P spectrum analyzer I'd only had for a few hours, than the engineer who had it for two years. I was configuring them and teaching the other techs long before one was freed up for my bench(es). He referred to the advanced menus as a "Bunch of useless garbage", but you had to use them daily. He couldn't even change it from the IEEE-488 printer it was set for when it was purchased, and four others didn't know where to find the settings.

Few freshly minted EEs would have designer level skills. Of course that doesn't stop some ppl hiring them in that capacity.

Graham

... Yes, he did. So what?