Re: Computer Grade

William E. Sabin wrote:
"Computer Grade Capacitor" might possibly refer to the low value of internal
series resistance and inductance which are important parameters in switching
regulator power supplies.

Well, maybe "low inductance" by 1960's standards. A computer power
supply would have to filter 60Hz, or maybe 400Hz ripple then. Yes,
there were switching supplies back in the 60's/70's too, but then
switching frequencies were much much lower (think about it: they used
2N3055's or their predecessors, transistors that take a millenium to
turn off!) than typical switching supplies today.

Modern low-ESR low-inductance caps are undoubtedly superior if you're
designing 150kHz switching supplies today. Heck, many of the modern
regulator chips will only be stable if they are operated into
capacitors that have an ESR above a minimum and below a maximum
number. There's a reason why there are 87 different 220uF 6.3V
capacitors in the Digikey catalog :-).

Clearly for their purposes, surplus 2N3055's and old big-can "computer
grade capacitors" can be put to very good use in many ham power
supplies. Make sure you get some LM723's too, a very versatile part
that modern parts (each good in their own narrow niche) have not
completely replaced yet!

(I did lament here on Usenet when the CA3046 was discontinued a year
or two ago... a shame! But the LM723 will outlive it!)

Tim.

.

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