The "References: " header got too long. I've snipped it in a
different editor.

On Wed, 15 Apr 2009 01:49:36 +0000, DoN. Nichols wrote:
On 2009-04-15, James Waldby ... wrote:

[ ... ]

Hmm ... if I had a TIG welding setup, the argon would be a good
choice (along with machining up a metal case with an O-ring seal and a
fill and vent valve). I wonder what would happen should I pump it down
to a fairly good vacuum (other than it leaking air back in over time). I
wonder whether the cells are allergic to vacuum.

I thought of vacuum also. A minute or two with google didn't answer
that question, although it gave lots of links to old hearing aids that
used a vacuum-tube rather than transistor, and vacuum-cleaners for
hearing aids, and remarks that putting the tab back on a zinc-air
hearing-aid battery apparently doesn't extend its life. You could see
if a WeinCell survives vacuum ok and let us know

Probably not -- at least not now. I am fighting a sore throat
which is a follow-on to Bacterial Conjunctivitis between my first and
second Cataract surgery. (At least I don't have to use my throat to
type. :-)

[...]
Depending on what the current draw is and how stable it is, you might
be able to use something like the dual-diode BAV199 in a 0.05"x0.12"
SOT-23 package. [to drop 6V from 2 li cells to 5V]

Hmm ... I've not measured the current draw yet -- but I suspect
that there will be a significant variation from displaying '1's to
displaying '8's, since it is a LED readout, not LCD like most more
recent ones.

I misunderstood that earlier, and thought the LED referred to was used
in position sensing, which would have a more stable current.

That was being used too.

But with
an LED display, not only could there be large variations in current, it
also might over-tax 2032 coin cells.

Rather small LED readouts, so it may not be too bad. It remains
to be seen when I feel up to testing the current from a lab bench
supply.

Perhaps consider using four NiMH
AAA's, for example lined up in a tube attached to the underside of the
caliper.

Ugly! And awkward to handle.

That would deliver about 5V through most of the discharge
curve. Or maybe find a flat rectangular cell-phone battery the right
size to attach on the back of the caliper, and use an LDO regulator
(like TC10145.0VCT713) to get 5V.

That might work. But I would want a switch to turn off the
regulator between uses.

[ ... ]

The mention of the gold bonded diodes reminded me of my first
employer -- Transitron -- who got their start in the semiconductor

[ ... ]

They also had another device -- a 4-lead device in a TO-5 can
which they called the "binistor". It was a mesa style silicon
transistor with an extra lead bonded wrong -- overlapping two zones, and
it behaved as a bistable device. So -- you could make a flip-flop with
a single device -- before integrated circuits allowed it in a single
chip. :-)

I've heard of Transitron and stabistors, but don't recall binistors, even
though I've got some 4-leaded parts with specs like that, from ca. 1966.

This would have been about 1960. IIRC, the part number was 3N35
or 3N31 -- something close to that.

It sounds like Transitron may have been an interesting place to work!

It was. But unfortunately, it was a summer job.

And the discovery of the binistor was through an accidental
mis-bonding and someone seeing whether it could be salvaged by prper
re-bonding. :-)

Enjoy,
DoN.