On 2011-11-22, P E Schoen <paul@pstech-inc.com> wrote:> "Gunner Asch" wrote in message > news:aa0kc750e2tsad3028cqpm25aer8aus1mn@4ax.com... > >> 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. -- Remove oil spill source from e-mail Email: <BPdnicholsBP@d-and-d.com> | 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 ---
Repaired Harbor Freight digital caliper
Started by ●November 19, 2011
Reply by ●November 21, 20112011-11-21
Reply by ●November 21, 20112011-11-21
On Nov 21, 9:08=A0pm, "DoN. Nichols" <BPdnichol...@d-and-d.com> wrote:> On 2011-11-21, dagmargoodb...@yahoo.com <dagmargoodb...@yahoo.com> wrote: > > > On Nov 20, 9:55=A0pm, "Martin Riddle" <martin_...@verizon.net> wrote: > >> <dagmargoodb...@yahoo.com> wrote in message > > >>news:07d0ac35-1cf3-4ed1-ba85-cd32f2f6ea0b@p2g2000vbj.googlegroups.com..=.> > >> > 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 > > =A0 =A0 =A0 =A0 [ ... ] > > >> 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. =A0Apart 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. > > =A0 =A0 =A0 =A0 Actually -- there *are* some "solar powered" ones -- by M=itutoyo> IIRC. =A0They would probably be excellent used daily in a well-illuminate=d> 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.> =A0In my shop, often dark for days at a time, until a project lures > me there, the replaceable batteries are a better choice. > > =A0 =A0 =A0 =A0 I did recently get an auto-darkening welding hood from Ha=rbor> 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. =A0I'll proabl=y> eventually have to perform surgery and replace the rechargeable cells in > there. =A0There is a temptation to provide a connection for an AC-powered > trickle charger so I can store it more conveniently. =A0What would be > particularly nice would be an induction coupled charger like those for > electric toothbrushes. =A0Just put it on a stand and expect it to be full=y> charged when I come back. > > =A0 =A0 =A0 =A0 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
Reply by ●November 21, 20112011-11-21
"DoN. Nichols" wrote in message=20 news:slrnjclve8.op3.BPdnicholsBP@Katana.d-and-d.com...> On 2011-11-21, Martin Riddle <martin_rid@verizon.net> 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=20 just as well have it display "OFF". I bought a high-end headlamp from Coleman a few years ago http://www.coleman.com/coleman/ColemanCom/detail.asp?CategoryID=3D1116&pr= oduct_id=3D2000000265# and every time I went to use it the batteries (4 AA) were dead. I = measured=20 the current draw when turned off, and it was something like 300 uA, = which=20 should have provided 8000 hours (almost one year) for the 2500 mA-hr=20 batteries. But I was getting only a few weeks before finding them = exhausted.=20 Maybe the current increased as the battery voltage dropped. I usually = used=20 rechargeable NiMH and they might have been old and tired. But, still, = there=20 is no reason for 300 uA standby current on a flashlight. Even if it had = a=20 microcontroller, a typical PIC18F2420 draws only 11 uA while running, = and=20 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=20
Reply by ●November 21, 20112011-11-21
"DoN. Nichols" wrote in message=20 news:slrnjcm1ee.op3.BPdnicholsBP@Katana.d-and-d.com...> 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=20 probably $20 on clearance, so I agree, in that case. But most = flashlights=20 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=20 case for a spare. I also put the other three cells in their original=20 packaging in there. I plan to use the calipers more now that I can = depend on=20 them (and know how to fix them). Usually I don't do much precision=20 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=20 fortunately I had removed it (but kept in the case) when I had tried to = fix=20 them a few years ago with no joy. When I opened it recently, the cell = was=20 rusty and there was some liquid that had oozed out. I've also had some = NiMH=20 AA cells that leaked. But probably the silver cells are better made and = the=20 chemicals may be less aggressive. Now that I've found an on-line source = with=20 good pricing I think I'll stick with them, although it's tempting to get = the=20 Chinese copies for 10 cents each. Paul=20
Reply by ●November 21, 20112011-11-21
On Nov 21, 9:34=A0pm, "P E Schoen" <p...@pstech-inc.com> wrote:> "DoN. Nichols" =A0wrote in message > > news:slrnjclve8.op3.BPdnicholsBP@Katana.d-and-d.com... > > > On 2011-11-21, Martin Riddle <martin_...@verizon.net> wrote: > >> Why bother including an on off switch? > > It is an off switch to turn the *display* (only) back on. =A0They > > 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.colem=an.com/coleman/ColemanCom/detail.asp?CategoryID=3D1116&...> and every time I went to use it the batteries (4 AA) were dead. I measure=d> 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 exhaust=ed.> Maybe the current increased as the battery voltage dropped. I usually use=d> rechargeable NiMH and they might have been old and tired. But, still, the=re> 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.comI 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
Reply by ●November 22, 20112011-11-22
On Mon, 21 Nov 2011 19:32:51 -0500, "P E Schoen" <paul@pstech-inc.com> 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-batterydepot?_trksid=p4340.l2563Thanks!!! 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
Reply by ●November 22, 20112011-11-22
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.
Reply by ●November 22, 20112011-11-22
On 2011-11-22, dagmargoodboat@yahoo.com <dagmargoodboat@yahoo.com> wrote:> On Nov 21, 9:08�pm, "DoN. Nichols" <BPdnichol...@d-and-d.com> wrote: >> On 2011-11-21, dagmargoodb...@yahoo.com <dagmargoodb...@yahoo.com> 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: <BPdnicholsBP@d-and-d.com> | 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 ---
Reply by ●November 22, 20112011-11-22
On 2011-11-22, P E Schoen <paul@pstech-inc.com> wrote:> "DoN. Nichols" wrote in message > news:slrnjcm1ee.op3.BPdnicholsBP@Katana.d-and-d.com...[ ... ]>> 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: <BPdnicholsBP@d-and-d.com> | 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 ---
Reply by ●November 22, 20112011-11-22
"DoN. Nichols" <BPdnicholsBP@d-and-d.com> wrote in message news:slrnjcom60.2vi.BPdnicholsBP@Katana.d-and-d.com...> On 2011-11-22, dagmargoodboat@yahoo.com <dagmargoodboat@yahoo.com> wrote: >> On Nov 21, 9:08 pm, "DoN. Nichols" <BPdnichol...@d-and-d.com> wrote: >>> On 2011-11-21, dagmargoodb...@yahoo.com <dagmargoodb...@yahoo.com> >>> wrote: > > [ ... ] > > > 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? > > [ ... ]You use the LED as a shunt regulator. tm
