🚀 go-pugleaf

In article <1992Nov17.165023.29174@julian.uwo.ca> wlsmith@valve.heart.rri.uwo.ca (Wayne Smith) writes:
>I've got some big electrolytic caps (20000 to 60000 uf, 16 to 40 volts),
>and I was thinking of putting them across the 5V and 12V power supplies
>in my pc.  I would think that cap's that big would provide maybe 1
>second of backup power.  

I think that asking for one second would be a little much.  Here's hwy:

Consider: Let's let your 5V line drop by 1V, to 4V.  TTL chips aren't
speced to work that low, but if you're lucky, maybe they will.  Next let's
assume that that 486 DX2/66 number masher of yours draws 5A.  This is
probably conservative, too, but anyway...  We'll also assume that the
current being drawn is constant, since, between 4 and 5V, it probably
won't change that much.  Again, all of this is going to happen in 1s.

Now then... I=C*dv/dt, or V-Vo=1/C*(integral of) I (WRT t).  1=1/C*5 -->
C=5 FARADS.  That's 83 of those 60000uF capactiros in parallel. :-)

						---Joel Kolstad