"Computer Grade"

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
Ed B.
Posts: 45
Joined: Wed Sep 24, 2003 1:01 am
Contact:

"Computer Grade"

Post by Ed B. » Wed May 31, 2006 10:35 pm

Hi,

A question that has bothered me for years.
What, in a capacitor, earns the title - "Computer Grade" ?
Is it some electrical characteristic or materials it is made of -(plates, insulator, ) voltages, AC or DC, the casing, terminals, etc ?
TNX fer any answer.

Ed B.

cato
Posts: 366
Joined: Sun Sep 07, 2003 1:01 am
Contact:

Post by cato » Thu Jun 01, 2006 4:14 am

I believe that --Computer Grade-- is a marketing term that has little technical meaning. If it means anything at all, I think it means that the manufacture believes the part is appropriate for use as a power supply filter cap in a computer where the output of the switching power supply has a considerable amount of ripple and the load has a considerable amount of ripple.

This would imply that the capacitor is designed to deal with internal heating and/or has a low ESR (equivalent series resistance) at supply/clock frequencies. How are caps designed to deal with heat? Shrug... I assume they are a bit bigger than --non computer grade-- caps...and maybe use an electrolyte that can handle the temps and current.

Mostly I would suggest ignoring the label and looking at the specs of the parts you are considering in light of the circuit you intend to use them in.


http://www.cde.com/mpdf/hes.pdf

rshayes
Posts: 1286
Joined: Tue Mar 04, 2003 1:01 am
Contact:

Post by rshayes » Thu Jun 01, 2006 6:07 am

"Computer grade" was a term applied to a specific construction for aluminum electrolytic capacitors. The case was a drawn aluminum case with a bakelite cap. The terminals were usually aluminum studs tapped for 10-32 screws. The vent was a rubber plug in the cap, rather than the scored case used on most of todays designs. The case was enclosed in a plastic insulating sleeve as a standard feature.

These were usually fairly large capacitors. The diameter ranged from about 1 inch to over 3 inches. The length was usually about 4 to 5 inches, but could be shorter or longer. The larger cases could have capacitances as high as 100,000 microfarad at around 10 volts.

There was no provision for mounting incorporated in the case design. They were usually mounted with a mounting bracket that clamped on to the capacitor and had two ir threee mounting feet.

A great many of these were used in computer power supplies. This may have been the reason for the "computer grade" name.

User avatar
dacflyer
Posts: 4550
Joined: Fri Feb 08, 2002 1:01 am
Location: USA / North Carolina / Fayetteville
Contact:

Post by dacflyer » Thu Jun 01, 2006 11:12 am

the version of computer grade caps i am used to are ones that can handle hi heat and frequencys , and they seem to be a bit smaller too, especially in switching power supplies.

but yes also to the giant stud mount and clamp case ones, they are as big as beer cans etc. i actually got a box full of them, i am thinking to put them on e-bay for sale or even here.. they would be awsome for a hi power stereo or power supply....

Ed B.
Posts: 45
Joined: Wed Sep 24, 2003 1:01 am
Contact:

Post by Ed B. » Thu Jun 01, 2006 7:02 pm

Thanks, guys.

Your answers were pretty close to what I had thought about the term "Computer Grade." Additionally, I had thought the use of that term was a 'sales pitch.'

Ed B.

Post Reply

Who is online

Users browsing this forum: No registered users and 48 guests