mkopp@xxxxxxxxxx wrote:
>Please cc any rapid answers to me as well as list as I am on digest.
>
>1. SN/age. Is there a list on the Web anywhere that correlates serial
>numbers with the ages/models of OM-1? This camera is an MD, with the
>MD badge on the leatherette to the right of the lens as you look at
>the front of the camera (not the apparently earlier model with the
>badge poorly stuck to the chrome on the other side, next to the
>rewind button). The serial number is seven digits, beginning with 138.
>
Lots of stuff you are looking for, including how to tell manufacture
date and some data points for early OM-1s is here.
<http://olympus.dementia.org/M-1/>.
>3. Batts. Are people actually still buying PX 625 mercury batteries
>(such as from PX625.com) and using them either in the States or
>shipping them out to other countries? PX625.com makes you swear on a
>stack of old batteries that you won't actually use them anywhere
>they're prohibited.
>
>If not, what are you folks actually using? (Yes, I know John says the
>best compromise is any 1.5 V silver oxide.)
>
Some of us still have PX625 batteries. They have a long shelf life. The
2 other options involve 1.55v silver oxide cells
1. Have the camera internally converted to the new voltage.
2. Use the C.R.I.S. MR-9 adapter. Be sure to use the correct battery.
Older ones used the 357, nower ones use the 386. Battery pops in the
adapter, which is the same size and shape as a 625.
>Why does it appear there are no other 1.35 V large or small button batteries?
>
Battery voltage depends on the chemistry. The only other chemistry that
has a similar voltage to mercury is zinc/air. Wein makes batteries to
replace the PX625s, but they have short life after opened to air, so
aren't very practical for casual use.
>And, in OM lore, was the OM-1 actually designed electronically around
>some specific characteristics of that type/voltage of mercury
>batteries, and what might those have been, that prevents any other
>battery from working right. Was it a current factor?
>
1. Voltage, see chemistry, above.
2. Voltage stability with time. Mercury batteries maintain almost the
same voltage over their whole useful life, then drop precipitously, thus
assuring accurate readings as long as the meter works at all.
3. Silver Oxide, while not quite as good, can be designed for similar
characteristics. The 357 and 386, among others are like this. The EPX13
is not and is a poor choice for meters.
>4. Batt mods. Battery compartment modification. I can't tell (after a
>search of several years of this list and John Hermanson's site and
>googling my fingers off) if the OM-1 battery mods that are out there,
>including John's and the MR 9 adapter, have an electronic component
>to adjust the voltage of 1.5x V batteries to 1.35 V (or even if that
>is desirable).
>
Yes, they all use either a resistor, the poorest choice, or a diode,
which has a small forward voltage drop. None are a perfect replication
of the PX625, and will lead to small errors. A vast amount of info on
the whole subject is here
<http://olympus.dementia.org/Hardware/PDFs/batt-adapt-US.pdf>
Moose
The olympus mailinglist olympus@xxxxxxxxxx
To unsubscribe: mailto:olympus-request@xxxxxxxxxx?subject=unsubscribe
To contact the list admins: mailto:olympusadmin@xxxxxxxxxx?subject="Olympus
List Problem"
|