[sdiy] German Speakers needed.

[harrybissell]

These days it is very easy to retrofit a ni-cad battery backup with a
lithium
battery. I'd start with a 3.6V lithium battery (maybe a 1/2AA or AA...)
and add a shottky diode in series with the positive lead. With the power
on..
the shottky is reverse biased. Power off...its memory backup.

If you have the room in the case... three ordinary DRY CELL batteries
can work as well... but you have to chnge them every three years or so.
Use the same
shottky technique.

There will be a diode to steer the voltage to the memory... its better
if you connect the cathode of the shottky to this point. Less voltage
drop this way.

I wouls NOT recommend using a ni-cad. They suck like a BBD !  when they
leak or explode the chemicals form intermetallic compounds with the
solder or solder plate... and these new alloys WILL NOT melt at normal
soldering temperatures.
The only way to remove them is mechanically (scrape scrape scrape)...
its so bad that often its better to cut and bypass these runs with wire
from good (clean) points.

So forget the ni-cads. I'd prefer the dry-cell for cheap, or the lithium
for better
performance.  Don't use heavy-duty alkalines... if you can find them,
regular carbon
cells are better... alkalines self-discharge faster (so they DON'T last
as long as the
cheap-o's)

H^) harry