On Mon, Nov 16, 2009 at 06:22:26AM -0800, Rich Shepard wrote:
>   I use this small wireless access point and it tends to quit functioning on
> a too frequent basis. Suddenly there's no network connection from the one
> portable that accesses the LAN and 'Net wirelessly and we need to unplug the
> Linksys and plug it back in. This power cycling resets it and it begins
> working again.

Older Linksys transformer-based wallwart AC adapters are crap. 
A full power interruption generates a reset and a clean restart. 
A brownout, perhaps caused by a furnace blower motor kicking
in, causes the voltage level to sag, which can cause the
Linksys processor to lose state and go zombie.  There is no
watchdog circuit to detect that.

This happens more often if the barrel connector from the wall
wart to the access point is mildly corroded.  If you clean it,
there is a small chance the failure rate will diminish (but
not go away).  Maybe not, the plating is not thick on those,
and scrubbing off the plating makes things worse.

Your best bet is to find a used laptop AC adapter that produces
the same DC voltage.  Or use a laptop "external battery".
See http://www.keithl.com/Linksyspower.html

Newer Linksys units with electronic "switcher" AC adapters?  There
should be fewer problems if the adapters have a large energy storage
capacitor, but I wouldn't bet on it.  A laptop adapter which provides
lots of power will have a large capacitor and can power the Linksys
for a second or so, long enough to survive a motor startup.

A double-conversion "online" battery backup is also good.  This
is the kind that uses wall power to charge the battery, and uses
battery voltage to synthesize uninterruptable power.  The "offline"
or "bypass" backups just pass along the voltage sag, and only kick
in after power stops for a sizable fraction of a second.  Online
UPS units are more expensive and less efficient, so the typical
retail UPS is offline, and won't help your Linksys.

BTW, it is possible to "brick" your Linksys if a brownout occurs
during programming, so there is a risk to updating the firmware
without a trustworthy power supply.

Keith

-- 
Keith Lofstrom          [email protected]         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs
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