On 2008-12-25, Winston wrote:
DoN. Nichols wrote:
On 2008-12-24, Steve W. wrote:
(...)
Allows you to use a 386/SR43 cell in place of the PX-13 cells. I have a
couple in different cameras. They work pretty good.
Ouch! 27.50 UKP *each*, and the caliper needs four of them.
Maybe $165 (USD) assuming a 1.5:1 ratio, since I am too lazy to look up
the current exchange rate. :-) That costs more than either the Mitutoyu
or the Starrett calipers from eBay auctions.
Say DoN, would you please look at the second illustration in:
http://www.willegal.net/photo/srt/srt-mercury.htm
It implies your best choice is a type 675 battery at $1.31 each in the
6 pack.
Hmm ... except for the following footnote:
*** Does not account for zinc-air batteries limited lifetime due
to exposure to air
The way mine would get used, the cells would probably die
between jobs.
And, of course, he is testing them for use in camera metering
systems -- would probably work in the Nikon Photomic metering finder, or
in the old Miranda spot meter, but not sure about the digital caliper,
which I think has a greater current (it is running at least two LEDs as
well as the photocells and comparator circuits and counters. (I really
should set up a bench supply to provide 5.26V and measure the current --
both when active and when shut "off". This will tell me what I can get
away with. But it is too cold in the shop right now to try that. :-)
Two 3V cells in series with a silicon diode (typically 0.7v
drop, and I need 0.64V drop -- *if* I make a new battery holder for the
system.
Cell dimensions:
http://www.duracell.com/oem/Primary/Zinc/675.asp
That would require making adaptor collars for each of four
cells, because the holder holds four cells, and depends on the bulge
ring to make contact to hook them in series. Or -- perhaps I should
consider making a new holder. (I really should take a few close-up
shots of the holder and post links to them.)
I think that I would prefer two 3V cells and a silicon diode in
series to the zinc-air cells, which start dying the moment you energize
them by pulling off the sealing tape. (The cells have to be exposed to
air to start them working, and they don't stop until they die.)
http://www.walmart.com/catalog/produ...ct_id=10242698
Price is pretty good. Two packs would give me three reloads of
cells.
Thanks,
DoN.
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