[Leica] Mercury battery solution for M5, Leicaflex, etc.??

[frank.dernie at btinternet.com (FRANK DERNIE)]

Hi Simon,
that was my belief also. Because mercury batteries
produce a very stable voltage until exhausted they
were chosen in many aplications where a voltage
reference was required. Electronic components are
cheap and reliable today so a super stable voltage
source is easily produced using other sorts of
battery. No camera which has a circuit designed using
the particular characteristics of a mercury battery
will be likely to be accurate over the life of a
different type of battery unless an some sort of
voltage stabiliser is added.
I think the Wein cell or an adapter (I seen to
remember chris 9 adapter ??) is necessary for the
meter to retain its accuracy. OTOH how accurate do you
need to be :-)
Frank 
Frank
--- Simon PJ <simonpj@mac.com> wrote:

> Thanks for this information, Didier.
> 
> I vaguely remember a potential problem to do with
> the voltage stability of
> alkaline batteries compared to the mercury
> batteries: that the mercury
> batteries retain a relatively steady voltage until
> they fail, while the
> alkaline batteries are constantly reducing in
> voltage. Presumably this is
> something that the meter electronics have to be able
> to compensate for, and
> may be a potential problem for the M5, Leicaflex,
> etc. in which the meter
> circuits were designed to deal with a constant 1.35V
> 
> It's quite likely that I have remembered this
> wrongly, and invented the
> problem!
> 
> Best,
> 
> Simon. 
> 
> 
> On 7/10/05 12:40 pm, "Didier Ludwig"
> <rangefinder@screengang.com> wrote:
> 
> > Simon,
> > 
> > All "new" mercury batteries I had went down after
> a short time. The best is to
> > modify the camera's battery tray from 1.35V to
> 1.5V for the newer alkaline
> > batteries (there are some in the PX625 size). The
> job is to solder a little
> > electric resistance module that reduces the
> voltage for 0.15V. I had let this
> > done with a Konica Auto-S3 and a Rollei XF 35, for
> CHF20 ($16 or ?9) each
> > camera. Before that I had used the 1.5V batteries
> and corrected it with the
> > ISO setting (don't remember how much, I had
> compared it to my M6's
> > lightmeter).
> > 
> > Weincell has alternative 1.35V mercury-free
> batteries, but they are quite
> > expensive. 
> > 
> > Didier
> > 
> >> Is it still possible to get hold of 'fresh'
> mercury batteries for the
> >> cameras?
> >> Many thanks,
> >> Simon.
> >> Cambridge, UK.
> > 
> > 
> > 
> > 
> > 
> > 
> > _______________________________________________
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> for more information
> 
> 
> 
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