In a message dated 8/18/2002 5:05:31 PM Eastern Daylight Time,
[EMAIL PROTECTED] writes:
> Comparing it to my Spotmatic the baseplate looks exactly
> the same size with everything in the same place. Has anyone tried fitting a
> K1000 baseplate to a Spotmatic to enable the use of the readily available
> s76/ LR44 battery?
>
Very interesting..But even if you could , the Spotty wont be happy.
Spotmatics are designed for 1.35V mercury batteries. These cells
were very well suited for small electronic devices because they delivered
their current via consistent 1.35V for most of their effective lifespan.
LR44 size alkalines deliver 1.5V very inconsistently.They are "hot"
for about 3 mos then deteriorate fairly rapidly.As they age they will
deliver less and less current UNDER LOAD although they test "good"
on a battery tester (light load). LR44 size SILVER OXIDES like the
excellent Everyready #357 begin life at 1.55V and can deliver consistent
current for most of their lifespan. List members with bodies using LR44
type cells should use SILVER OXIDE cells for more consistent results.
Unfortunately SilverOxide cells will deliver TOO much current for your
Spotty's meter. By the formula:
E = l x R ( E=volts , I = current ,
R=resistance)
the Spotty meter (the "R" of the formula) gets 1.55/ 1.35 or 15% too
much current....
For you Spotmatic guys, a reasonable alternative is the 1.4V Zinc-Air
type hearing aid batteries.They are small so require a home-made little
washer to hold them in the chamber. Unfortunately their lifespan is very
limited ( 2 months?) and the Spotty meters work them HARD.
Regards,
Bob
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