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davidallancole 6th December 2007 04:23 PM

Which cap would you pick?
2 Attachment(s)
I am looking at two different capacitors here. They are axial, 4700uF, 25V and have a large difference in price. Other than they are usually to low for power rails in an amp, what would you pick based of the spec sheets I have attached and why?

This first cap is $2.98 a piece.

davidallancole 6th December 2007 04:28 PM

2 Attachment(s)
This cap is $9.44 a piece.

AndrewT 6th December 2007 04:48 PM

the cheaper one has higher ripple capacity and lower ESR.
It seems to be an easy decision to save all that money.

Nordic 6th December 2007 05:09 PM

The diffirence between those caps lies in the temperature rateing, the high temp one will likely also have a significantly extended lifetime compared to the other... especialy when it is not used at that full temp.

davidallancole 6th December 2007 05:12 PM

Thanks for the comments guys.

So if you keep the cheaper ones cool, they would be better based on lower ESR and the fact they are almost 3 times cheaper.

Nordic 6th December 2007 05:27 PM

Yes it should be fine..

jacco vermeulen 6th December 2007 06:05 PM


Originally posted by davidallancole
This cap is $9.44 a piece.

That cap is a BC-118 series (aka Beyschlag) and has a extremely long life expectancy.
Anything over 250,000 hours/40C is really good, the BC-118 goes mucho much higher.

davidallancole 6th December 2007 06:21 PM

Really good in ways of reliablility and long life or also good in ways of being a good power supply cap. I guess what I really need to learn is what makes a good power supply cap and what makes a bad power supply cap. Any hints or leads?

Nordic 6th December 2007 06:41 PM

That can depend on lots of things... like do you have loudspeaker protection... if no, you would idealy like a powersupply that is not going to keel over some random day in the forseeable future...

So lots of posibibilities are possible, in some implementations it is also critical to have long life components... like medical and aviation electronics... you don't want any surprises...

davidallancole 6th December 2007 07:11 PM

I am looking at these for mostly chip amps. I will be building things in the future out of descrete parts, but would probably not add protection in general, because I will be just doing experiments. An amp might be in my system for a few months to a year at most.

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