On Sun, 20 Nov 2011 19:57:32 -0500, Rich Webb
wrote:

I tried a paste of cream of tartar from the spice rack in the kitchen on
the battery terminals on a long forgotten remote control that had spewed
its battery guts to make a nasty, green mess of the copper-nickel
strips. Worked amazingly well, better than anything else I've tried for
that particular problem. YMMV, of course.

Cream of tartar is potassium bitartrate. Mix the powder with some
white vinegar or any weak acid and you get a paste that can be used as
a cleaner:
http://www.ehow.com/how_5758669_clean-vinegar-cream-tartar.html

For cleaning up the green slime left after a battery exceeds its
warranty, I use ammonia cleaner. I also like the foam it produces.
Copper (cupric) oxide is soluble in ammonium hydroxide, but not in
water.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 2011-11-20, N_Cook wrote:
Dave Plumpe wrote in message
m...
Not only do they remember where Zero is, they even keep track of any
movement that occurs while they're turned off. Smart little devils.

I find myself more & more reaching for the digital ones for the ease of
swapping between inches & millimeters.

[ ... ]

"N_Cook" wrote in message
...

I've never used the new-fangled ones - do you have to do a clean jaws,
close
jaws, zero calibration check/0 reset ,every time you use them ? as the
count
must be lost each time it is switched off




An engineer told me never close the jaws of a micrometer or vernier calipers
for storage, leave the jaws open slightly.

A micrometer should never be stored closed. (Thermal changes in
dimensions can stress the components and reduce accuracy. Vernier
calipers should not have a problem as long as you don't *lock* them
closed -- either with the slide or the fine adjust slide.

Do these digitally things require
the jaws closing before switching off ? How do they know of any movement of
the jaws when switched off elsewise?

Most modern digital calipers only shut off the display, and keep
the counters and sensors powered up, so they can know where they are
when the display is switched back on -- and some will even switch the
display back on when it senses motion above some minimum value.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Jeff Liebermann wrote:
On Sun, 20 Nov 2011 23:47:58 +0000 (UTC), gregz
wrote:

Jeff Liebermann wrote:
On Sat, 19 Nov 2011 22:19:11 -0600, Jim Yanik
wrote:

I wonder if Cramolin/DeOxit would work on the conductive strip?

http://siber-sonic.com/electronics/caig.html
Sorta. The original Cramolin contained about 5% oleic acid, which is
great for removing surface oxidation, but is also mildly corrosive to
copper. The current version is DeOxit from Caig Labs. It comes in an
amazing variety of forms, and is allegedly non-corrosive.
http://store.caig.com/s.nl/sc.2/.f
The MSDS data shows the active ingredients as a "trade secret". Oh
well.

I never have been able to get much visible effect of so called corrosion
removers. Oleic acid probably being best, but supposedly the cramolin
chemist also had input on making deoxit. On a short term test I can visibly
wipe off oxide with an alcohol swipe, being just as effective. Most of the
removing is mechanical in nature, and any liquid helps.

The oleic acid is only about 5% of the contact cleaner. Over a period
of time, it will help remove any oxide deposits. However, at such a
low concentration, it should not be expected to dissolve a substantial
oxide accumulation. Basically, any detergent will do as well if you
can live with the residue.

More on Cramolin:
http://www.pitt.edu/~szekeres/caigcram.htm
http://siber-sonic.com/electronics/caig.html

Cleaning brass clocks. Note the section on oleic acid.
http://www.abbeyclock.com/brass2.html
The oleic acid therefore has two functions: to remove
the oxide layer from the metals and to act as a soap
to remove the dirt and oils. The cleaning solution
has about 90% ammonia solution with about 5% oleic
acid and 5% acetone added, thereby leaving plenty
of excess ammonia molecules to keep the solution
alkaline.
The acetone is to accelerate evaporation. Oleic acid also has the
advantage of being common, cheap, and non-toxic. It's a by product of
corn and veggie oil production.

http://www.dialcover.com/components.html
Scroll down to "Cease and Desist" contact cleaner. Much the same as
my home made formula except I won't use acetone because it eats
plastic. Ordinary isopropyl alcohol is safer.

Homebrew cleaners and protectors:
http://www.pitt.edu/~szekeres/cleaner.htm
The comments on the effects of silicones plus salt in WD40 are
interesting.

Yes, some old navy guy contacted me and I stuck it in there. Have not
updated anything for a while.

Greg szekeres

On 2011-11-20, Jeff Liebermann wrote:
On Sun, 20 Nov 2011 13:38:36 -0000, "N_Cook"
wrote:
An engineer told me never close the jaws of a micrometer or vernier calipers
for storage, leave the jaws open slightly.

True. With gear type calipers, the lubricating grease tends to
migrate to that position. If a sufficiently filthy environment, an
lump of dirt encrusted grease will be left in that position. If it
happens to be at 0.0, then it will be difficult to accurately
calibrate the mechanism.

But he said "Vernier calipers" which have no such mechanism.
Though people tend to lock the slides, so thermal stress distortion
could be a problem with them stored closed and locked.

There are also some minor reasons, such as
the tendency for two parallel surfaces to trap moisture between them
and rust.

Assuming non stainless steel jaws. (I've never seen calipers
with carbide faced jaws, unlike good micrometers.)

[ ... ]

How do they know of any movement of
the jaws when switched off elsewise?

Only the display is turned off. The pulse counting mechanism is still
operating and functional. The downside is that the battery will be
dead in about 6-9 months. Most include a spare LR44 battery. I had
to buy a pile of them to keep my calipers going. Somehow, the battery
is usually dead when I need to use them.

50 batteries for $3.75
http://www.ebay.com/itm/220751739681

There is your problem -- cheap cells. Don't use the LR44 (those
are alkaline batteries), use the SR44 and SR357 (Silver Oxide cells,
with much longer life). Then things will probably last at least six
months in storage. The SR44 and SR357 are pretty much interchangeable.
I don't even know why there are the two series -- though you will often
find them with both designators marked on the same cell or packaging. :-)

I have an expensive set of Starett calipers (both metric and US). I
use them more often than the electronic variety, mostly out of habit.
My most useful measuring tools are my 6" pocket steel scale and a tape
measure.

While I tend to use the digital calipers by preference. Half as
many calipers needed to cover the metric and inch measurements.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

gregz wrote:
Jeff Liebermann wrote:
On Sun, 20 Nov 2011 23:47:58 +0000 (UTC), gregz
wrote:

Jeff Liebermann wrote:
On Sat, 19 Nov 2011 22:19:11 -0600, Jim Yanik
wrote:

I wonder if Cramolin/DeOxit would work on the conductive strip?

http://siber-sonic.com/electronics/caig.html
Sorta. The original Cramolin contained about 5% oleic acid, which is
great for removing surface oxidation, but is also mildly corrosive to
copper. The current version is DeOxit from Caig Labs. It comes in an
amazing variety of forms, and is allegedly non-corrosive.
http://store.caig.com/s.nl/sc.2/.f
The MSDS data shows the active ingredients as a "trade secret". Oh
well.

I never have been able to get much visible effect of so called corrosion
removers. Oleic acid probably being best, but supposedly the cramolin
chemist also had input on making deoxit. On a short term test I can visibly
wipe off oxide with an alcohol swipe, being just as effective. Most of the
removing is mechanical in nature, and any liquid helps.

The oleic acid is only about 5% of the contact cleaner. Over a period
of time, it will help remove any oxide deposits. However, at such a
low concentration, it should not be expected to dissolve a substantial
oxide accumulation. Basically, any detergent will do as well if you
can live with the residue.

More on Cramolin:
http://www.pitt.edu/~szekeres/caigcram.htm
http://siber-sonic.com/electronics/caig.html

Cleaning brass clocks. Note the section on oleic acid.
http://www.abbeyclock.com/brass2.html
The oleic acid therefore has two functions: to remove
the oxide layer from the metals and to act as a soap
to remove the dirt and oils. The cleaning solution
has about 90% ammonia solution with about 5% oleic
acid and 5% acetone added, thereby leaving plenty
of excess ammonia molecules to keep the solution
alkaline.
The acetone is to accelerate evaporation. Oleic acid also has the
advantage of being common, cheap, and non-toxic. It's a by product of
corn and veggie oil production.

http://www.dialcover.com/components.html
Scroll down to "Cease and Desist" contact cleaner. Much the same as
my home made formula except I won't use acetone because it eats
plastic. Ordinary isopropyl alcohol is safer.

Homebrew cleaners and protectors:
http://www.pitt.edu/~szekeres/cleaner.htm
The comments on the effects of silicones plus salt in WD40 are
interesting.

Yes, some old navy guy contacted me and I stuck it in there. Have not
updated anything for a while.

Greg szekeres

I bought some oleic acid from bill. I tried diluting it with isopropyl
alcohol, seems to mix well.

My old cans of spray of Contaclean got all sticky and the metal was looking
bad where it contacted the fluid build up. I think it also gummed up pots.
Contaclean is Cramolins replacement for cramolin. I'm not trying to order
it anymore because it costs watt too much to ship into the states.
Interesting though, my old vial of cramolin never gummed up on the injector
tube. The can of Contaclean clearly states to remove before operating, with
a cleaner. Gummy!!
I can't remember if I dried pure oleic acid to test for gumminess. Probably
does.
Deoxit does not gum. Never tried to dry up pure red caig in the vial
injector.
Deoxit is only 5% concentration in the spray.

Greg

I've ignored the "Followup-To: " header, because I believe that this
also belongs in at least rec.crafts.metalworking, where I am following
it, and I would miss my own followup and any responses if it were kept
to a single group as requested.

On 2011-11-20, Fred Abse wrote:
On Sun, 20 Nov 2011 06:41:03 -0600, amdx wrote:

That's why I like the Dial calipers vs Digital Calipers, no concern
about batteries or electronics.

I prefer a "proper" vernier. At least you can verify those by eye.

Depends on how old the eye is and how good the illumination is.

I never
did trust digital calipers to hold their zero and not skip under workshop
conditions, Half a lifetime dealing with incremental encoders has made me
wary.

The old B&S ones, which used glass encoders in the slot where
the rack gear would otherwise be were sensitive to coolant in the slot.
But the modern units seem to be quite good at not skipping.

I *might* trust a Mitutoyo digital caliper or height gage in inspection
room conditions.

I trust them (as much as a caliper *can* be trusted compared to
a micrometer) in shop conditions as well.

Dial calipers have all sorts of racks and gears to go sloppy.

Agreed -- or to pick up bits of swarf and skip.

I suppose nobody under fifty knows how to read a real vernier, or a slide
rule for that matter ;-(

I know how to use both -- but then I am (well) over fifty. :-)

But there have been verniers on the thimbles of the better
micrometers much more recently than that, so presumably some of the
younger crowd know.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Mon, 21 Nov 2011 03:33:20 +0000 (UTC), gregz
wrote:

Jeff Liebermann wrote:
Homebrew cleaners and protectors:
http://www.pitt.edu/~szekeres/cleaner.htm
The comments on the effects of silicones plus salt in WD40 are
interesting.

Yes, some old navy guy contacted me and I stuck it in there. Have not
updated anything for a while.

Greg szekeres

Oh, those are your pages. Nice info and thanks.

The silicone and salt atmosphere problem is real. It forms sodium
silicate, which is water soluable. Add almost any acid, and you get
silicic acid. Heat and dry that you get silica gel, which is quite
hard and not very soluable in anything. It takes a while, but it does
happen.

I used to work for a marine radio manufactory in the 1970's. Customers
would sometimes use various lubricants loaded with silicone to clean
pots and switches. It would work, but about a year later, we would
get the radios back with seriously intermittent pots and switches. No
amount of solvent cleaning would fix them, so we just replaced them.
We just assumed they were internally corroded or salt encrusted. I
didn't discover the silicone and salt atmosphere problem until many
years later (when I repeated the mistake on a consulting project).

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Mon, 21 Nov 2011 03:57:48 +0000 (UTC), gregz
wrote:

I bought some oleic acid from bill. I tried diluting it with isopropyl
alcohol, seems to mix well.

Olive oil works almost as well. It's about 50% oleic acid. My
solution is mostly Coleman fuel (naphtha), some olive oil, and a
little alcohol. It works and leaves the radio smelling "organic".

My old cans of spray of Contaclean got all sticky and the metal was looking
bad where it contacted the fluid build up. I think it also gummed up pots.

Well yes. Such cleaners (and Cramolin) are mostly mineral oil. Remove
the volatiles and antioxidants, and what's left is mineral oil. There
are different types of mineral oils: paraffin, naphtha, various
petroleum distillates, and mixtures. The paraffin residue left after
evaporation might be the gum that you're seeing.

Contaclean is Cramolins replacement for cramolin. I'm not trying to order
it anymore because it costs watt too much to ship into the states.

It appears that Contaclean is the same as the old Cramolin Red
(R-100). Mostly mineral oil (hexane) and isopropyl alcohol. MSDS:
http://www.farnell.com/datasheets/1493224.pdf
Hmmm... looks like the oleic acid was removed.

Interesting though, my old vial of cramolin never gummed up on the injector
tube. The can of Contaclean clearly states to remove before operating, with
a cleaner. Gummy!!
I can't remember if I dried pure oleic acid to test for gumminess. Probably
does.

I would blame the mineral oil instead, especially since there doesn't
seem to be any oleic acid in the Contaclean reformulation. Oleic acid
is much like corn oil or olive oil. It will leave a gummy residue
under the correct conditions. However, there is only 5% oleic acid in
the bottle, which isn't enough to leave much residue. If there's
plenty of residue, it's probably the mineral oil.

Deoxit does not gum. Never tried to dry up pure red caig in the vial
injector.
Deoxit is only 5% concentration in the spray.

Greg
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 20 Nov 2011 22:41:49 -0800, Jeff Liebermann
wrote:

It appears that Contaclean is the same as the old Cramolin Red
(R-100). Mostly mineral oil (hexane) and isopropyl alcohol. MSDS:
http://www.farnell.com/datasheets/1493224.pdf
Hmmm... looks like the oleic acid was removed.

Oops. It's still there, but well hidden. It's listed as an
"aliphatic hydrocarbon", which includes fatty acids such as oleic
acid.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 21 Nov 2011 03:24:37 GMT, "DoN. Nichols"
wrote:

On 2011-11-20, Bob Engelhardt wrote:
Jamie wrote:
I have the HF digital calipers and I need to pull the battery when not
in use other wise, it'll be dead next time I need it. It seems to drain
quite fast.
...

I have one & the battery lasts quite a while (doesn't get used much).
Maybe a different model. Or a different batch. Or different spots on
the quality curve G.

Or different quality of battery as I just posted above. :-)

Enjoy,
DoN.

Many 99c stores sell a flatpack of 5-10 standard 357 batteries for a
dollar.

So I use 2 batteries a year. Or even 3. Im still way ahead of the curve
when SR44s are $3 each

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

Spehro Pefhany wrote in message
...
On Sun, 20 Nov 2011 17:45:47 -0800, the renowned Jeff Liebermann
wrote:

On Sun, 20 Nov 2011 16:47:25 -0800 (PST), "Ron D."
wrote:

I have a cheap Caliper too and it recently went flakey.

I did my standard trick: Remove battery. Short battery contacts:
Insert new battery. Worked.

My cheap electronic caliper goes nuts when I transmit on UHF anywhere
near it. However, it doesn't require the battery removal ordeal to
recover. I just reset to zero and continue.

Mine uses an LR44 and you HAVE TO use an LR44, not a substitute
battery that you can get a Radio Shack.
Mechanically they are not the same.

I beg to differ. The general package name is LR44 in an 11.6mm dia x
5.4mm thick package alkaline cell. There are slight variations, but
the IEC LR1154 equivalents (LR44/LR154, A76, 157/303/357) are all the
same size. Where you can have problems is that the SR44/SR1154 silver
oxide cells come in the same package. They have about 50% more
capacity and a much flatter discharge curve. Some of the cheapo
calipers crap out below about 1.4V. The alkaline battery has plenty
of capacity left at 1.4V, but the caliper doesn't want to run. If
your caliper cames with a silver-oxide cell, it should probably use
silver oxide batteries. If it came with alkaline and has a short
battery life, it might be worthwhile trying silver-oxide. If you're
ambitious, it might be useful to run the caliper off a bench power
supply and check how low a voltage will work.

Be sure to check how high a voltage too, and report back. ;-)



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers:
http://www.trexon.com
Embedded software/hardware/analog Info for designers:
http://www.speff.com


If I had one of these I'd fit onto the calipers a small solar cell and diode
to trickle charge the original battery ie not specifically rechargeable ,
and replace the lid of its casing with a glass panel and leave on a bright
position .

I never have been able to get much visible effect of so called corrosion
removers. Oleic acid probably being best, but supposedly the Cramolin
chemist also had input on making deoxit. On a short term test I can
visibly
wipe off oxide with an alcohol swipe, being just as effective. Most of the
removing is mechanical in nature, and any liquid helps.

I'm inclined to disagree. Cramolin/DeOxit definitely work on tin- and
nickel-plated surfaces. They are not as effective on gold-plated surfaces;
ProGold does a better job. It isn't just a matter of mild abrasion; a
chemical reaction of some sort is needed.

On 11/19/2011 11:19 PM, Jim Yanik wrote:

use Boeing Boeshield T-9 to prevent the rusting of your tools.

I wonder if Cramolin/DeOxit would work on the conductive strip?


Hello, and DeoxIT is the best thing I've ever come across for cleaning
and de-oxidizing electrical contacts. It also does wonders with
scratchy volume and tone pots and it'll be long while before you have to
apply it again. Sincerely,


--
J. B. Wood e-mail:

Jeff Liebermann wrote in
:


Homebrew cleaners and protectors:
http://www.pitt.edu/~szekeres/cleaner.htm
The comments on the effects of silicones plus salt in WD40 are
interesting.


WD-40 is mostly kerosene.

--
Jim Yanik
jyanik
at
localnet
dot com

On Mon, 21 Nov 2011 10:36:03 -0600, Jim Yanik
wrote:

Jeff Liebermann wrote in
:


Homebrew cleaners and protectors:
http://www.pitt.edu/~szekeres/cleaner.htm
The comments on the effects of silicones plus salt in WD40 are
interesting.


WD-40 is mostly kerosene.

Close. It's mostly Stoddard Solvent, also known as mineral spirits.
http://www.snopes.com/inboxer/household/wd-40.asp
http://en.wikipedia.org/wiki/WD-40
http://en.wikipedia.org/wiki/Stoddard_solvent
50% Stoddard solvent (i.e., mineral spirits: primarily hexane,
somewhat similar to kerosene)
25% Liquefied petroleum gas (presumably as a propellant; carbon
dioxide is now used instead to reduce WD-40's considerable
flammability)
15+% Mineral oil (light lubricating oil)
10-% Inert ingredients

Reverse engineering at its best:
http://www.wired.com/science/discoveries/magazine/17-05/st_whatsinside

USA MSDS sheet:
http://www.wd40company.com/files/pdf/msds-wd494716385.pdf

The key ingredient is a sulfactant (wetting agent), to reduce surface
tension and make it "cling" to objects and "puddle" water. My
guess(tm) the reason it took 40 trys is that they had a difficult time
finding one that would work in a solvent solution.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Th 357 and the LR44 ARE NOT quite the same in experience, The LR44
seems to have a slightly domed top and it seems to make a difference
in all of my products that use them. I can't find evident to support
my claim, but experience, unfortunately.

In general, the LF357's fit a little looser in the holder and the
LF44's are easier to insert.

Jeff Liebermann wrote:
On Mon, 21 Nov 2011 10:36:03 -0600, Jim Yanik
wrote:

Jeff Liebermann wrote in
:


Homebrew cleaners and protectors:
http://www.pitt.edu/~szekeres/cleaner.htm
The comments on the effects of silicones plus salt in WD40 are
interesting.


WD-40 is mostly kerosene.

Close. It's mostly Stoddard Solvent, also known as mineral spirits.
http://www.snopes.com/inboxer/household/wd-40.asp
http://en.wikipedia.org/wiki/WD-40
http://en.wikipedia.org/wiki/Stoddard_solvent
50% Stoddard solvent (i.e., mineral spirits: primarily hexane,
somewhat similar to kerosene)
25% Liquefied petroleum gas (presumably as a propellant; carbon
dioxide is now used instead to reduce WD-40's considerable
flammability)
15+% Mineral oil (light lubricating oil)
10-% Inert ingredients

Reverse engineering at its best:
http://www.wired.com/science/discoveries/magazine/17-05/st_whatsinside

USA MSDS sheet:
http://www.wd40company.com/files/pdf/msds-wd494716385.pdf

The key ingredient is a sulfactant (wetting agent), to reduce surface
tension and make it "cling" to objects and "puddle" water. My
guess(tm) the reason it took 40 trys is that they had a difficult time
finding one that would work in a solvent solution.


Good info. Darn, I liked to use the can as a flame thrower to kill pests
with the flammable propellant. Bags worms met their doom.

Greg

"Gunner Asch" wrote in message
...

Many 99c stores sell a flatpack of 5-10 standard 357 batteries
for a dollar.

I'm not sure I'd trust them in something any more expensive than a
flashlight. I have seen them corrode and leak. And the only thing the 99
cent store might be willing to do is give you another pack or refund your
dollar.

So I use 2 batteries a year. Or even 3. Im still way ahead of the
curve when SR44s are $3 each

I just purchased four genuine SR44s from an eBay store, for $3, including
first class mail shipping. The same company also has larger packs for quite
a bit less.
http://stores.ebay.com/RL-batterydep...id=p4340.l2563

I also measured the current draw on my calipers, and it's about 12.5 uA
either on or off. It seems to spike a bit when turned on. (So do I

They are specified at about 175 mAhr, according to http://www.sr44.com/, so
lifetime should be about 14000 hrs or 1.5 years, but the spec is for a low
voltage of 1.3V, which is probably below the limit of the electronics in the
caliper, at least for the low battery indicator.

Here is a handy list of the various sizes with different chemistry and their
mA-hr capacities: http://en.wikipedia.org/wiki/List_of_battery_sizes

Paul
www.pstech-inc.com

Harbor Freight Has the 6" dial Caliper on sale 11/24

http://www.harborfreight.com/preview...tm_source=1003

Mikek

amdx wrote:
Harbor Freight Has the 6" dial Caliper on sale 11/24

http://www.harborfreight.com/preview...tm_source=1003


Mikek
Nice, I like the metal cutting saw they have there just off to the right..

Think I'll do a stop in for that.

Jamie

On 11/21/2011 6:49 PM, Jamie wrote:
amdx wrote:
Harbor Freight Has the 6" dial Caliper on sale 11/24

http://www.harborfreight.com/preview...tm_source=1003


Mikek
Nice, I like the metal cutting saw they have there just off to the right..

Think I'll do a stop in for that.

Jamie


Do note, it is pneumatic.
Fine if your setup for it.
Mikek

On 2011-11-21, Martin Riddle wrote:

wrote in message
...
On Nov 20, 8:45 pm, Jeff Liebermann wrote:
On Sun, 20 Nov 2011 16:47:25 -0800 (PST), "Ron D." wrote:

I have a cheap Caliper too and it recently went flakey.

[ ... ]

same size. Where you can have problems is that the SR44/SR1154
silver
oxide cells come in the same package. They have about 50% more
capacity and a much flatter discharge curve. Some of the cheapo
calipers crap out below about 1.4V. The alkaline battery has plenty
of capacity left at 1.4V, but the caliper doesn't want to run. If
your caliper cames with a silver-oxide cell, it should probably use
silver oxide batteries. If it came with alkaline and has a short
battery life, it might be worthwhile trying silver-oxide. If you're
ambitious, it might be useful to run the caliper off a bench power
supply and check how low a voltage will work.

I just measured a Harbor Freight (Chinese) 8-incher.

Drain: 13.5uA (off), 14.5uA (on)
Battery low threshold (blinking display): 1.37V
Lowest operating voltage: 1.01V

So, it's clearly made for silver-oxide cells. The battery low
threshold is set appropriately for a silver oxide cell (e.g. SR-44).

It's a lousy threshold for using alkalines--they're barely broken in
at that voltage.

14.5uA means a year from a silver oxide cell--that's not horrible.

[ ... ]

Why bother including an on off switch?

It is an off switch to turn the *display* (only) back on. They
sometimes make it also turn the display back off to make people feel
better. :-)

The auto-turn-off time of the display is usually good enough.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
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--- Black Holes are where God is dividing by zero ---

On 2011-11-21, wrote:
On Nov 20, 9:55*pm, "Martin Riddle" wrote:
wrote in message

...




I just measured a Harbor Freight (Chinese) 8-incher.

Drain: 13.5uA (off), 14.5uA (on)
Battery low threshold (blinking display): 1.37V
Lowest operating voltage: 1.01V

[ ... ]

Why bother including an on off switch?

It's really not worth it for 1uA.

If I designed these, I'd shoot for 2uA active draw, like the
Mitutoyos, and set the battery low threshold at 1.1V (for alkalines).
The battery consumption is the biggest fault with these. Apart from
that, they're impressive.

I sometimes think about wiring up a "AAA" or solar cell and just
forgetting it, but for $0.50 a year it's not worth the trouble.

Actually -- there *are* some "solar powered" ones -- by Mitutoyo
IIRC. They would probably be excellent used daily in a well-illuminated
shop. In my shop, often dark for days at a time, until a project lures
me there, the replaceable batteries are a better choice.

I did recently get an auto-darkening welding hood from Harbor
Freight which is solar powered, and based on what I have read about them
dying if not used regularly, I've put mine on a folding workstool facing
out the window so it sees daylight to maintain the charge. I'll proably
eventually have to perform surgery and replace the rechargeable cells in
there. There is a temptation to provide a connection for an AC-powered
trickle charger so I can store it more conveniently. What would be
particularly nice would be an induction coupled charger like those for
electric toothbrushes. Just put it on a stand and expect it to be fully
charged when I come back.

If the charge is good enough to work on the first strike, it
should work fine for the rest of the day, because it will be getting a
charge boost from the arc -- close enough to vigorous sunlight. :-)

Enjoy,
DoN.

--
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Email: | Voice (all times): (703) 938-4564
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--- Black Holes are where God is dividing by zero ---

On 2011-11-22, P E Schoen wrote:
"Gunner Asch" wrote in message
...

Many 99c stores sell a flatpack of 5-10 standard 357 batteries
for a dollar.

I'm not sure I'd trust them in something any more expensive than a
flashlight.

Well ... I've paid more for *some* flashlights (typically
multi-LED ones) than for *some* digital calipers (import from a
hamfest), so it is a toss-up there. :-)

I have seen them corrode and leak. And the only thing the 99
cent store might be willing to do is give you another pack or refund your
dollar.

If you are going to leave the calipers for more than a week,
pull the cell(s) and store them separately -- perhaps in a small zip-loc
baggie, so they don't damage anything else when leaking.

FWIW I've not seen the Silver Oxide ("SR" prefix) ones leak in anything
in which I have used them.

Enjoy,
DoN.

--
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Email: | Voice (all times): (703) 938-4564
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On Nov 21, 9:08*pm, "DoN. Nichols" wrote:
On 2011-11-21, wrote:

On Nov 20, 9:55*pm, "Martin Riddle" wrote:
wrote in message

....

I just measured a Harbor Freight (Chinese) 8-incher.

Drain: 13.5uA (off), 14.5uA (on)
Battery low threshold (blinking display): 1.37V
Lowest operating voltage: 1.01V

* * * * [ ... ]

Why bother including an on off switch?

It's really not worth it for 1uA.

If I designed these, I'd shoot for 2uA active draw, like the
Mitutoyos, and set the battery low threshold at 1.1V (for alkalines).
The battery consumption is the biggest fault with these. *Apart from
that, they're impressive.

I sometimes think about wiring up a "AAA" or solar cell and just
forgetting it, but for $0.50 a year it's not worth the trouble.

* * * * Actually -- there *are* some "solar powered" ones -- by Mitutoyo
IIRC. *They would probably be excellent used daily in a well-illuminated
shop.

I saw a solar-powered Mitutoyo at a flea market and was intrigued, but
resisted. Something about having a glass window on a machine tool
close to all that hard steel just didn't sit well--it brought up
memories of scratched and broken watch crystals.

OTOH, I paid $10 for most of my HF calipers. Those you can take
chances with. Using the 8x25mm solar panel from a $1 calculator, a
super capacitor for storage, and an LED as a regulator diode was my
notion. $2 in parts, $500 labor ;-).

I fitted one to the lathe carriage--best thing I ever did.
Removable. I fitted another to the tailstock ram. With it you can
bore to 0.002" depth every time without even trying. Magic.

*In my shop, often dark for days at a time, until a project lures
me there, the replaceable batteries are a better choice.

* * * * I did recently get an auto-darkening welding hood from Harbor
Freight which is solar powered, and based on what I have read about them
dying if not used regularly, I've put mine on a folding workstool facing
out the window so it sees daylight to maintain the charge. *I'll proably
eventually have to perform surgery and replace the rechargeable cells in
there. *There is a temptation to provide a connection for an AC-powered
trickle charger so I can store it more conveniently. *What would be
particularly nice would be an induction coupled charger like those for
electric toothbrushes. *Just put it on a stand and expect it to be fully
charged when I come back.

* * * * If the charge is good enough to work on the first strike, it
should work fine for the rest of the day, because it will be getting a
charge boost from the arc -- close enough to vigorous sunlight. :-)

Sounds like a LiIon cell. If so, those can't be allowed to go dead,
as you've surmised.

--
Cheers,
James Arthur

"DoN. Nichols" wrote in message
...

On 2011-11-21, Martin Riddle wrote:

Why bother including an on off switch?

It is an off switch to turn the *display* (only) back on. They
sometimes make it also turn the display back off to make
people feel better. :-)

The auto-turn-off time of the display is usually good enough.

Still, there's no benefit to turning off the display, in this case. Might
just as well have it display "OFF".

I bought a high-end headlamp from Coleman a few years ago
http://www.coleman.com/coleman/Colem...id=2000000265#
and every time I went to use it the batteries (4 AA) were dead. I measured
the current draw when turned off, and it was something like 300 uA, which
should have provided 8000 hours (almost one year) for the 2500 mA-hr
batteries. But I was getting only a few weeks before finding them exhausted.
Maybe the current increased as the battery voltage dropped. I usually used
rechargeable NiMH and they might have been old and tired. But, still, there
is no reason for 300 uA standby current on a flashlight. Even if it had a
microcontroller, a typical PIC18F2420 draws only 11 uA while running, and
only 100 nanoamps in sleep mode! So, I just pop out one of the batteries
while I'm not using it. There's no easy place to install a switch.

Paul
www.muttleydog.com

"DoN. Nichols" wrote in message
...

Well ... I've paid more for *some* flashlights (typically
multi-LED ones) than for *some* digital calipers (import
from a hamfest), so it is a toss-up there. :-)

Yes, the Coleman headlamp I mentioned elsewhere lists for $50, and I paid
probably $20 on clearance, so I agree, in that case. But most flashlights
with coin cells are pretty much disposable.

If you are going to leave the calipers for more than a week,
pull the cell(s) and store them separately -- perhaps in a small
zip-loc baggie, so they don't damage anything else when leaking.

That's what I am going to do. There is a cutout in the foam of the caliper
case for a spare. I also put the other three cells in their original
packaging in there. I plan to use the calipers more now that I can depend on
them (and know how to fix them). Usually I don't do much precision
machining, and I have a cheap plastic dial caliper that is good to about
0.01" and is immune to humidity and most abuse.

FWIW I've not seen the Silver Oxide ("SR" prefix) ones leak in
anything in which I have used them.

I think the original cell in the HF caliper was actually alkaline, and
fortunately I had removed it (but kept in the case) when I had tried to fix
them a few years ago with no joy. When I opened it recently, the cell was
rusty and there was some liquid that had oozed out. I've also had some NiMH
AA cells that leaked. But probably the silver cells are better made and the
chemicals may be less aggressive. Now that I've found an on-line source with
good pricing I think I'll stick with them, although it's tempting to get the
Chinese copies for 10 cents each.

Paul

On Nov 21, 9:34*pm, "P E Schoen" wrote:
"DoN. Nichols" *wrote in message

...

On 2011-11-21, Martin Riddle wrote:
Why bother including an on off switch?
It is an off switch to turn the *display* (only) back on. *They
sometimes make it also turn the display back off to make
people feel better. :-)
The auto-turn-off time of the display is usually good enough.

Still, there's no benefit to turning off the display, in this case. Might
just as well have it display "OFF".

I bought a high-end headlamp from Coleman a few years agohttp://www.coleman.com/coleman/ColemanCom/detail.asp?CategoryID=1116&...
and every time I went to use it the batteries (4 AA) were dead. I measured
the current draw when turned off, and it was something like 300 uA, which
should have provided 8000 hours (almost one year) for the 2500 mA-hr
batteries. But I was getting only a few weeks before finding them exhausted.
Maybe the current increased as the battery voltage dropped. I usually used
rechargeable NiMH and they might have been old and tired. But, still, there
is no reason for 300 uA standby current on a flashlight. Even if it had a
microcontroller, a typical PIC18F2420 draws only 11 uA while running, and
only 100 nanoamps in sleep mode! So, I just pop out one of the batteries
while I'm not using it. There's no easy place to install a switch.

Paulwww.muttleydog.com

I measured some ordinary NiMH cells' self-discharge, 1,600mAH, @ 1.6mA
IIRC. The high-capacity rechargeables are wickedly worse. I've got
one set that won't hold a charge much over two weeks, no kidding,
even brand-new. Self-discharge current on the order of 5-7mA.

There are low-self-discharge NiMH that hold a charge much longer,
sometimes up to a year. Highly recommended. Ray-O-Vac Hybrids, Sanyo
Eneloop, and Duracell has some too.

--
Cheers,
James Arthur

On Mon, 21 Nov 2011 19:32:51 -0500, "P E Schoen"
wrote:


I just purchased four genuine SR44s from an eBay store, for $3, including
first class mail shipping. The same company also has larger packs for quite
a bit less.
http://stores.ebay.com/RL-batterydep...id=p4340.l2563

Thanks!!!

Ill check em out and stock up!!

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

P E Schoen wrote:

I've also had some NiMH AA cells that leaked.


I have the control panel & 'Rabbit Semiconductor' RCM2000 computer
board from an Ineco Basic tubing bender that was damaged by a leaking
3.6 V 80 mAh NiMH battery. That leak cost a local business $700 for a
failed $5 battery. The tool was eight years old. I called them
yesterday and told them to log the date the board was installed, and to
have me replace it in two years as PM. The symptoms were that the
machine started bending the wrong angles, and different angles without
changing the setup. A trace below the battery was eaten by the leaking
chemicals. I'll try to get a good photo before I return it to them. It
might save someone else a wad of cash, or convince a shop owner to let
you check for leaking batteries. The machine was used on a regular
business, a few days per week, so it wasn't caused by long term storage.


--
You can't have a sense of humor, if you have no sense.

Jeff Liebermann wrote in
:

On Mon, 21 Nov 2011 10:36:03 -0600, Jim Yanik
wrote:

Jeff Liebermann wrote in
m:


Homebrew cleaners and protectors:
http://www.pitt.edu/~szekeres/cleaner.htm
The comments on the effects of silicones plus salt in WD40 are
interesting.


WD-40 is mostly kerosene.

Close. It's mostly Stoddard Solvent, also known as mineral spirits.
http://www.snopes.com/inboxer/household/wd-40.asp
http://en.wikipedia.org/wiki/WD-40
http://en.wikipedia.org/wiki/Stoddard_solvent
50% Stoddard solvent (i.e., mineral spirits: primarily hexane,
somewhat similar to kerosene)
25% Liquefied petroleum gas (presumably as a propellant; carbon
dioxide is now used instead to reduce WD-40's considerable
flammability)
15+% Mineral oil (light lubricating oil)
10-% Inert ingredients

Reverse engineering at its best:
http://www.wired.com/science/discoveries/magazine/17-05/st_whatsinside

USA MSDS sheet:
http://www.wd40company.com/files/pdf/msds-wd494716385.pdf

The key ingredient is a sulfactant (wetting agent), to reduce surface
tension and make it "cling" to objects and "puddle" water. My
guess(tm) the reason it took 40 trys is that they had a difficult time
finding one that would work in a solvent solution.



I'd not go by Wikipedia,I'd go by the actual WD-40 MSDS.
if you read the MSDS -for each ingredient- listed for WD-40 on the WD-
40 MSDS(like I did),you'll see that it's mostly kerosene.

--
Jim Yanik
jyanik
at
localnet
dot com

In article ,
Jim Yanik wrote:

USA MSDS sheet:
http://www.wd40company.com/files/pdf/msds-wd494716385.pdf

The key ingredient is a sulfactant (wetting agent), to reduce surface
tension and make it "cling" to objects and "puddle" water. My
guess(tm) the reason it took 40 trys is that they had a difficult time
finding one that would work in a solvent solution.



I'd not go by Wikipedia,I'd go by the actual WD-40 MSDS.
if you read the MSDS -for each ingredient- listed for WD-40 on the WD-
40 MSDS(like I did),you'll see that it's mostly kerosene.

I don't see either kerosene, or Stoddard solvent, by name in the MSDS.

Rather, I see "Aliphatic hydrocarbon" (CAS #64742-47-8) as the
ingredient with the highest concentration. Commonest synonym seems to
be "Hydrotreated light petroleum distillates." Usable as fuel oil or
solvent.

If I understand correctly, all of these petroleum distillates form a
continuum - most are mixtures of hydrocarbons with differing molecular
weights. I don't think there's a sharp physical cutoff between what
constitutes a "kerosene" and a "solvent" - it's all a matter of
convention.

According to the MSDS, WD-40 is a bit more than half solvent (about an
eighth is "LVP", presumably slower to evaporate?), about a quarter
light lubricating oil, a couple of percent of the secret-sauce
surfactant that Jeff was alluding to, CO2 for pressurization, and 10%
mixed "non-hazardous ingredients."

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Tue, 22 Nov 2011 11:30:34 -0800, (Dave Platt)
wrote:

In article ,
Jim Yanik wrote:

USA MSDS sheet:
http://www.wd40company.com/files/pdf/msds-wd494716385.pdf

The key ingredient is a sulfactant (wetting agent), to reduce surface
tension and make it "cling" to objects and "puddle" water. My
guess(tm) the reason it took 40 trys is that they had a difficult time
finding one that would work in a solvent solution.



I'd not go by Wikipedia,I'd go by the actual WD-40 MSDS.
if you read the MSDS -for each ingredient- listed for WD-40 on the WD-
40 MSDS(like I did),you'll see that it's mostly kerosene.

I don't see either kerosene, or Stoddard solvent, by name in the MSDS.

Rather, I see "Aliphatic hydrocarbon" (CAS #64742-47-8) as the
ingredient with the highest concentration. Commonest synonym seems to
be "Hydrotreated light petroleum distillates." Usable as fuel oil or
solvent.

If I understand correctly, all of these petroleum distillates form a
continuum - most are mixtures of hydrocarbons with differing molecular
weights. I don't think there's a sharp physical cutoff between what
constitutes a "kerosene" and a "solvent" - it's all a matter of
convention.

According to the MSDS, WD-40 is a bit more than half solvent (about an
eighth is "LVP", presumably slower to evaporate?), about a quarter
light lubricating oil, a couple of percent of the secret-sauce
surfactant that Jeff was alluding to, CO2 for pressurization, and 10%
mixed "non-hazardous ingredients."

Well, let's dive a bit deeper into the contents. The CAS number
identifies the exact ingredients. We have:
CAS % by weight
Aliphatic Hydrocarbon 64742-47-8 45-50%
That would be:
http://www.cdc.gov/niosh/ipcsneng/neng1379.html
Low odor paraffinic solvent, Dearomatized kerosine, Deodorized
kerosene. In other words, lamp oil as used in a kerosene lamp.

Petroleum Base Oil 25%
64742-58-1 Recycled motor oil
64742-53-6 Distillates(petroleum), hydrotreated light naphthenic.
Also known as Coleman fuel
64742-56-9 Solvent-dewaxed light paraffinic.
64742-65-0 Solvent-dewaxed heavy paraffinic.

LVP Aliphatic Hydrocarbon 12-18%
64742-47-8 Same as the first item. Kerosene.
My guess is that LVP means "low vapor pressure" which for solvents
means that it's slow to evaporate.

(gotta run...)

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On 2011-11-22, wrote:
On Nov 21, 9:08*pm, "DoN. Nichols" wrote:
On 2011-11-21, wrote:

[ ... ]

I sometimes think about wiring up a "AAA" or solar cell and just
forgetting it, but for $0.50 a year it's not worth the trouble.

* * * * Actually -- there *are* some "solar powered" ones -- by Mitutoyo
IIRC. *They would probably be excellent used daily in a well-illuminated
shop.

I saw a solar-powered Mitutoyo at a flea market and was intrigued, but
resisted. Something about having a glass window on a machine tool
close to all that hard steel just didn't sit well--it brought up
memories of scratched and broken watch crystals.

I've seen them only new, and decided that in my shop conditions,
they would not work very well. :-)

OTOH, I paid $10 for most of my HF calipers. Those you can take
chances with. Using the 8x25mm solar panel from a $1 calculator, a
super capacitor for storage, and an LED as a regulator diode was my
notion. $2 in parts, $500 labor ;-).

O.K. Do you know the maximum voltage that the solar panel is
likely to produce? And the voltage drop on the LED? I know that
silicon diodes are typically between 600 mV and 750 mV. Also, any clues
as to the maximum voltage that the calipers can tolerate long term?

[ ... ]

* * * * I did recently get an auto-darkening welding hood from Harbor
Freight which is solar powered, and based on what I have read about them
dying if not used regularly, I've put mine on a folding workstool facing
out the window so it sees daylight to maintain the charge. *I'll proably
eventually have to perform surgery and replace the rechargeable cells in
there. *There is a temptation to provide a connection for an AC-powered
trickle charger so I can store it more conveniently. *What would be
particularly nice would be an induction coupled charger like those for
electric toothbrushes. *Just put it on a stand and expect it to be fully
charged when I come back.

* * * * If the charge is good enough to work on the first strike, it
should work fine for the rest of the day, because it will be getting a
charge boost from the arc -- close enough to vigorous sunlight. :-)

Sounds like a LiIon cell. If so, those can't be allowed to go dead,
as you've surmised.

And -- they are supposedly not replaceable according to the
manual. :-) (You've got to cut the package apart to get to them.) There
is a web page describing how someone opened one up and set a holder for
two AA cells outside the package. I'm really tempted to go for the
induction charger when I finally have to dig into mine. But it is
significantly less expensive than auto-darkening ones from MSC -- to the
point where three HF ones match the cost of one from MSC. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 2011-11-22, P E Schoen wrote:
"DoN. Nichols" wrote in message
...

[ ... ]

If you are going to leave the calipers for more than a week,
pull the cell(s) and store them separately -- perhaps in a small
zip-loc baggie, so they don't damage anything else when leaking.

That's what I am going to do. There is a cutout in the foam of the caliper
case for a spare. I also put the other three cells in their original
packaging in there. I plan to use the calipers more now that I can depend on
them (and know how to fix them). Usually I don't do much precision
machining, and I have a cheap plastic dial caliper that is good to about
0.01" and is immune to humidity and most abuse.

Except for certain solvents. :-)

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Nov 22, 9:21*pm, "DoN. Nichols" wrote:
On 2011-11-22, wrote:

I saw a solar-powered Mitutoyo at a flea market and was intrigued, but
resisted. *Something about having a glass window on a machine tool
close to all that hard steel just didn't sit well--it brought up
memories of scratched and broken watch crystals.

* * * * I've seen them only new, and decided that in my shop conditions,
they would not work very well. :-)

OTOH, I paid $10 for most of my HF calipers. *Those you can take
chances with. *Using the 8x25mm solar panel from a $1 calculator, a
super capacitor for storage, and an LED as a regulator diode was my
notion. $2 in parts, $500 labor ;-).

* * * * O.K. *Do you know the maximum voltage that the solar panel is
likely to produce? *And the voltage drop on the LED? *I know that
silicon diodes are typically between 600 mV and 750 mV. *Also, any clues
as to the maximum voltage that the calipers can tolerate long term?

The max. solar panel voltage doesn't matter--the LED regulator clamps
the solar panel voltage, taking care of that.

Here's a sketch:

D1
.--||--+-----+---- (+) to caliper
+ | | |
.------. + | |
| | --- ---
| ---- | --- \ / ~~
| | C1| ---
| ---- | | | LED (red)
| | | |
'------' | |
- | PV | |
'--------+-----+--- (-) to caliper


C1 - A capacitor to power the caliper during momentary outages.
Optionally a super-cap., e.g. http://www.goldmine-elec-products.co...?number=G13133
(Note1: The PV will take HOURS of bright light to charge a super-
cap, so you might want to precharge the cap, then let the PV just
float it.)
(Note2: Super-caps have significant electrical leakage. If your
cap is too leaky, it'll never charge, and you'll be disappointed. I
haven't measured the above-linked PAS920 to see if this is the case.)

PV - http://www.goldmine-elec-products.co...?number=G17448,
or, stolen from the cheapest solar-powered calculator you can find.
Walmart and the dollar stores have some good candidates.
LED - shunt-regulates the PV output to a safe voltage.
D1 - 1n4148, prevents PV from draining a super-cap C1 when dark,
possibly not needed. (Depends on PV panel's dark leakage current.)


To set the voltage you'd choose an LED with a forward voltage of, say
1.6-1.8v. Three ordinary small-signal silicon diodes in series (e.g.
1n4148) wouldn't be a bad choice either. With surface-mount parts,
the ckt can be tiny.

If the voltage is too high it's not a matter of "long-term," the
caliper will die instantly. I don't know what that voltage is, but
I'd easily wager one of *my* $10 calipers that 2v is okay, and I'd
wager one of *yours* that 2.5v might be okay too. ;-)

--
Cheers,
James Arthur

wrote:
....

D1
.--||--+-----+---- (+) to caliper
+ | | |
.------. + | |
| | --- ---
| ---- | --- \ / ~~
| | C1| ---
| ---- | | | LED (red)
| | | |
'------' | |
- | PV | |
'--------+-----+--- (-) to caliper

....

Doncha' need a current limiter on the LED?

Bob

On 11/23/2011 2:05 PM, Bob Engelhardt wrote:
wrote:
...

D1
.--||--+-----+---- (+) to caliper
+ | | |
.------. + | |
| | --- ---
| ---- | --- \ / ~~
| | C1| ---
| ---- | | | LED (red)
| | | |
'------' | |
- | PV | |
'--------+-----+--- (-) to caliper

...

Doncha' need a current limiter on the LED?

Bob

Not if the PV cell's rated SC current is less than the max LED current
rating.

Bob Engelhardt wrote:
wrote:
...

D1
.--||--+-----+---- (+) to caliper
+ | | |
.------. + | |
| | --- ---
| ---- | --- \ / ~~
| | C1| ---
| ---- | | | LED (red)
| | | |
'------' | |
- | PV | |
'--------+-----+--- (-) to caliper

...

Doncha' need a current limiter on the LED?

Nup. It's a 'shunt regulator'.
http://en.wikipedia.org/wiki/Linear_...ener_regulator

--Winston

wrote:

(...)

I saw a solar-powered Mitutoyo at a flea market and was intrigued, but
resisted.

Next time, advise jump on it before someone else does.

I have two of those. They just keep working without
any issues. Well, except for turning off in low-light
situations. I just charge it up with the flashlight
and it works just fine. 'Way better than having to
run to the store for a $5 battery! They are fine tools
and have my highest recommendation.

--Winston