I couldn't resist this as an easy quick-a-minnit project.
It's a way to connect an external 1.5 volt supply to a digital
caliper, as in those used as DRO's on mills and so forth.
Means for holding the "battery" in place are left to the user's
imagination. I'll note that I have one caliper that has used duct
tape to hold the battery in place for years, one small piece of new
duct tape per battery change.
WHAT? no strain relief?
I'll only give you a 9.5 for leaving that off.
My last "5 minute job" a couple of weeks ago (Taking more like 45
minutes by the time I got done varnishing the handle.) was making a
menorah candle holder reamer. It's just a crude hand forged 5/16"
diameter spade bit epoxied into a piece of dowel.
I got tired of picking away with the point of a steak knife removing the
bits of wax and wick from those little 5/16" diameter candleholders so
we could insert new candles for the next of the eight nights of
Hanukkah, which is appropriately called "The festival of lights".
Having to clean a total of 44 burnt out candle ends over the week long
holiday made the project justifiable, as I didn't have a stubby
screwdriver I was willing to part with and convert for that purpose.
Happy New Year,
A 2 conductor pair pulled from a ribbon cable would be much more compact
and might allow the cover to be used with mods.
Dweller in the cellar
D> I couldn't resist this as an easy quick-a-minnit project.
Good idea. Another noted that the center lead could be brought out
the side of the "cell". On this particular caliper (HF), there is a
gap in the battery well (visible in the photo) that would pass such a
side-mounted pair of wires, and the cover would still stay on if a bit
of it was removed to pass the wires.
Mark II is always different (and sometimes better) than Mark I!
Thats way too easy. I'm thinking unwind a small transformer and wind a tiny
coil, then stuff it and a tiny surface mount rectifier, capacitor and
voltage regulator inside the battery compartment, then wind a larger coil
around and tape it to the outside of the battery door and send pulsing DC
or AC through the outside coil to inductively power the inner coil.
That should cost 10 times more than the cost of the batteries it would have
used in its whole life and take at least a few days to design, build, and
debug making it a successful project.
For those who don't know, the little door above the battery compartment
shown in the third photo has a 4 pin connector two pins of which are for
external power when these are used with electronic readouts. To improve
noise immunity you should replace the battery with a small capacitor.
OK, I'll bite on this one:
Do you have a dead electric toothbrush that charges with a cradel and no
exposed contacts? Could this be used somehow as a power source?
Charles Friedman DDS
Ventura by the Sea
New Years wishes to all
On my generic Chinese digital caliper - which seems to be pretty
typical of the kind that people are using for DROs - the battery
contacts are brought out to the data interface connector (a 4 way edge
connector), so it's easy to just power it from your controller. The
one 'gotcha' is the potential for the cable to pick up noise/hum &
confuse the measurement electronics in the caliper. When I convert
mine, I'll most likely put in a series resistor, an LED as a ~1.5V
shunt regulator, & a pair of small caps (10uF tantalum, 0.47uF
monobloc ceramic) to simulate a battery.
If your caliper starts giving whacky readings when you wire it up to
something, or power it with something other than the standard button
cell, you also need a little circuit like this. If anyone else wants
one, say so here, & I'll draw up a schematic for y'all.
Yep, same as mine.
Cute little adapter, too. Personally, I'd just solder some instrument
cable to the terminals, but then I do more electronics work than
metalwork anyway. ;)
Nice idea, but the stray field from the coil would send the caliper
electronics into epilectic fits. If you're determined to go to that
much trouble, you'd be better off with a little solar cell (one ratted
from one of those throwaway solar powered calculators would be ideal),
combined with a little tantalum capacitor to filter out the ripple
from your workshop lights.
This started out with an inquiry by Karl, who doesn't like soldering
teensy stuff. I can drop the little adapter in an envelope and mail
it to him with one stamp -- he'll have to supply the duct tape. The
little LM317-based regulator can be located very nearby -- it'd just
be a gob about the size of an acorn in the wires.
Geeezzzz, Don.... what I *really* expected from you would have been a
*miniature* hit n miss engine powering a small generator (DC of
course)..... all fitting in the space the original battery