Re: gEDA-user: Alarm clocks and switching regulators

[DJ Delorie <dj@xxxxxxxxxxx>]

> > I've got four of their 820uF/63v caps on my furnace board.  It's like
> > a 3 second UPS :-)
> 
> The 105C is a fairly big deal.  Is that a 5,000 hour lifetime part?

Yes.  I intentionally overspec'ed those because they're on the
*furnace*.  I.e. they're subjected to wider extremes than normal
home-internal devices.  Plus, I put four of them in parallel to cut
down the per-cap ripple current (and to save space).

> Not terrible, but marginal even for an alarm clock if you ask me.

Hmmm... what's in the alarm clock...

220u alel = 2k hours, 85c
 47u tant = 500k hours, 125c
150u tant = 500k hours, 125c
180u alel = 5k hours, 105c

Note that the 220u doesn't have much ripple on it; it's the bulk cap
for the wall wart.  I suppose I could replace that with an FC if it
dies, but even if it fails open the clock will still work.  It's there
mostly to guard against wiggling the power cord and interrupting the
power for a split second.

Of course, the clock *is* at room temperature all the time :-)


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