I just cancelled my Ebay account

[sarah_fox]

<blockquote>

<p>Buying for use I would avoid mercury battery at all cost as meter designed to depend on the stable voltage of mercury battery simply isn't a good design.</p>

</blockquote>

<p>You're saying that a voltage reference based on the natural properties of an electrochemical reaction are inferior to a voltage reference based on the electrical properties of a manufactured semiconductor? What a strange claim! The only thing inferior about a mercury cell is the toxicity of the mercury. It's not bad design. In fact in the context of a world that didn't care very much about heavy metal pollution, it's quite a <em>good</em> design. And some of the meters of the day (e.g. a Gossen Luna Pro) are still among the best you will find, even by today's standards, so long as they are kept calibrated and in good repair -- and perhaps recalibrated to silver oxide chemistry (almost as good as mercury). If a meter can deliver accuracy to maybe 1/10 stop, far finer grained than the 1/2 or 1/3 stop increment of most cameras, and far less significant then the inevitable implementation error of the photographer (e.g. exact targeting of meter), exactly what's the problem?</p>

[BrianS1664879711]

I'd have an adapter in it in less than 2 minutes and

be using it like I still use a LunaPro!

[bebu_lamar]

<blockquote>

<p> What a strange claim!</p>

</blockquote>

<p>We can do a test although it's hard to buy a mercury battery to test. I have a Fluke 8846A which has an accuracy of +/- 0.0024 % of reading. We can simulate a varying load and test it through out the life of the mercury battery against a simple voltage regulator chip. </p>

[sarah_fox]

<p>It seems odd to load-test a mercury cell. There's not much load from these meters; that's not how a mercury cell is used. There's a reason the cell lasts virtually forever. Heck, I once had a Genrad 1441c SPL meter with a small mercury cell soldered to the board as a voltage reference.</p>

<p>Anyway, be my guest. Load test a mercury cell. Then load-test your voltage reference circuit. It may show some variation too. In the end, with such micro-currents, you should be more interested in voltage stability. See here:</p>

<p>http://www.rokkorfiles.com/minolta/pix/batterychart.gif</p>

<p>Also factor in the fact that an exposure scale is logarithmic, so each stop is a doubling/halving of light. Put another way, our craft isn't as precise as we like to pretend it is. In the grand scheme of things, a few mV here or there isn't going to make a world of difference.</p>

[AlanKlein]

<p>Sarah: I really have to find that antique mercury anal fever thermometer. Always accurate. Never wears out.</p>

[BrianS1664879711]

The ultimate standard for human body temperature

measurement !

[shutterbud]

<p>Speak for yourself Alan. Mine snapped in two when I reailsed where it was supposed to go! EBAAAAAAAY!!<br>

It is funny to see The OP go on a rantathon while those around him reply in reasonable terms. Makes me feel sorry for the seller. </p>

[jim_momary]

<p>Bebu --<br>

For the DCV function of the 8846A it is +/- 0.0024% or reading plus, the additional +/- 0.0005 of scale (in this case you would be using the 10.00000VDC scale). So the entire accuracy figure becomes +/- 0.0000824V </p>

<p>:O) ...<br>

Still a darn good measurement, i.e. if one measured a 1.35DCV source, the best one could say was that the reading was between 1.3500824V and 1.3499176V given the accuracy of the measurement instrument itself.</p>

<p>This thread is now splitting sub-micron hairs. LOL</p>

<p>Jim M</p>