IM-17 Batteries

[Bob And Bettina Groh]

Regarding 'low drop out regulators' - there are a bunch of them today
that will (at 'light' loads) that will regulate well with only 50 mV or
so across them. You would need one of the adjustable one's with some
precision resistors (or a pot) to set the output voltage.  Should work
great and, with SMD devices, could be built up in quite a small space.
 Good point about the discharge characteristics.  If any other info
needed, I would be glad to look into the matter and provide a 'paper'
design.

73
Bob Groh, WA2CKY

Garey Barrell wrote:

> John -
>
> There really isn't a good replacement for a mercury cell.  There are
> many ways to get 8.4 V from a 9V battery, but the absolute voltage isn't
> the problem.  All batteries EXCEPT for the mercury battery have a
> "slope" discharge curve.  i.e., the voltage starts to decrease almost
> immediately, and continues until it reaches the minimum that will
> operate the equipment.
>
> On the other hand, a mercury battery has an almost flat discharge
> "curve" until just before end of life when it drops like a rock.  This
> is important for things like watches, light meters for photography,
> voltmeters or anything else that relies on a stable voltage.
>
> Photographers have gone to great lengths to make accommodations to keep
> their light meters accurate.  The only "good" answer is a voltage
> regulator, but not many regulators will regulate with less than a volt
> to work with.
>
> 73, Garey, K4OAH
> Atlanta
>
>
>
> John Barkow wrote:
>
>> Anyone know of a replacement for the 8.4V mercury battery for this
>> unit other
>> than a 9V battery?
>> Thanks, John kd6pt
>>
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