5 Mar
2005
5 Mar
'05
11:40 p.m.
James Fogg wrote:
It might not make a perfect solution, but you could
take 2 nicad cells (1.25V each) of similar diameter
and a shorter length (N size?) and place them in series
in shrink tubing to make a replacement cell.
Yeah - I thought about that. Don't want to go there if I don't have to, though.
(I did fail to mention in my original post that it requires 2 of these
little beasts, thus making a 5V supply necessary.)
Also check out the oddball batteries available for
photo equipment. There's a lot of odd voltages in
that category, though you might have to slightly
modify the cell holder (widen it a bit).
Yeah - thought about that, too. It is a fairly tight fit already, so
widening the battery compartment doesn't look feasible.
At this point, I'm thinking that if there isn't a direct replacement for
this cell, I'll just pay the bucks to get it refurbished so it can use
something more conveniently available.
Appreciate the suggestions though!
6 Mar
6 Mar
8:26 a.m.
At 08:40 PM 3/5/05 -0800, you wrote:
James Fogg wrote:
though.
It might not make a perfect solution, but you
could
take 2 nicad cells (1.25V each) of similar diameter
and a shorter length (N size?) and place them in series
in shrink tubing to make a replacement cell.
Yeah - I thought about that. Don't want to go there if I don't have to,
(I did fail to mention in my original post that it requires 2 of these
little beasts, thus making a 5V supply necessary.)
Then why don't you squeeze in a LDO 5 regulator and install two standard 3
volt Lithium batteries?
Joe
2:43 p.m.
New subject: 2.5V Lithium 'AA' sized batteries: Where to find?
Joe wrote:
Then why don't you squeeze in a LDO 5 regulator
and install two standard
3 volt Lithium batteries?
Unlike normal linear regulators, LDOs are very finicky. They are picky
about both the value and the ESR of their filter capacitors, and the
requirements vary considerably between different LDOs. They not only
have maximum ESR requirements, they have minimums as well! Pay very
close attention to the data sheet.
I recommend not using LDOs unless you're really experienced with these
issues, and even then you can still sometimes run into trouble.
For running 5V circuits from a pair of 3V lithium batteries, you
might be better off just using a normal silicon diode in series,
for a nominal 0.7V drop. However, the voltage drop decreases at
low currents, so this may not be adequate for a low power circuit.
That said, I've had pretty good results with the National Semiconductor
LM1117 LDO regulator when used in accordance with the design guidelines
in its data sheet. They are available in TO220 and various SMT packages,
with fixed or adjustable voltage, are fairly inexpensive, and are
available from Digikey.
http://www.national.com/pf/LM/LM1117.html
Eric
7074
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7074
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