On Thu, 09 Apr 1998 11:34:50 +0200, Marko Vrabec
<marko.vrabec@xxxxxxxxxxxxxxxx> wrote:
>Firstly, great thanks to everybody who contributed to "OM4T in cold
>weather" topic. I have decided to go for the DIY external battery pack,
>per instructions of F.van Lindert as relayed by R. Schätzl.
>
>Due to tight timing constraints (I leave for Spitsbergen on Sunday) I
>was not able to find anybody who could properly connect the adjustable
>voltage regulator chip for me. Therefore I am left with an option to use
>just two ordinary 1,5V cells as a power supply, in which case voltage
>regulator is not needed. However, my learned friend (who has a degree in
>electrical engineering) warned me, that the internal resistance of the
>1,5V source cells could produce dangerously high currents, which could
>smoke the electronics of my camera. This is not specifically mentioned
>in the DIY instructions.
>
>Does anybody have an opinion on this, or even experience? Is the
>volatge-regulator-less setup with 2 x 1.5V battery cells safe, or not?
Hello Marko.
It is a pity that I missed ealier messages on this topic (if there
were any in tthis list area). I could easily have sent you a 3 volt
low-drop voltage regulator connected to (for instance) a set of 3 pcs
1.5 volt alkalines or a 6v lithium battery, but it is too late for
that now.
Now for the two alkalines solution: Yes, AFAIK it is safe (but act as
if the regular disclaimer was in this position). I know it is safe in
the OM-2 I built this thing for, and I suppose it is safe for the 4T
as well. BTW, I think you could use a 3V lithium battery (123-type)
too.
The internal resistance of the alkalines, if it is indeed lower than
that of the small silver cells (which I doubt), would only be
important if the batteries were connected to a circuit which needs
current limiting but hasn't built that into itself (like with the old
type Olympus flash 310 and bounce-grip 1, not allowing NiCad or
lead-gel battery use).
I am pretty sure that the more modern 4T's will have built-in current
limiting. But again: it is too late for me to do a little
experimenting and make completely sure. If you want to play safe:
don't use very fresh alkalines which can start giving 1.60 volts, but
use used ones which give 1.50 volts. You will never empty them during
your trip (and the kids cannot replace them ;-).
Or...even better... take two silver batteries in a small box with
wires attached.... duplicating the original Olympus external battery
set almost completely.
Hope this helps, and enjoy your trip.
Frank van Lindert
Utrecht - Holland.
>
>> If the voltage connector is hard to find, you could use a poor man's
>> solution by only connecting two 1.5 volt alkaline cells (e.g. AA
>> cells) together with the cord. Special 2-cell cases do exist. In this
>> case you will have to check the voltage regularly, particularly when
>> the kids 'borrow' your cells and put their empty ones in instead...
>
>
>Best regards,
>
>Marko Vrabec
>Department of Geology, University of Ljubljana, Slovenia
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