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Linux Duracell CPU Load Monitor

Nixon8Pie writes "Know those little self-testing batteries? How would you like to monitor your computers load with them? Well, now ya can. 'These throwaway testers are quite clever: they use a layer of conductive ink that heats up when an electrical current runs through it, in combination with a layer of thermally-activated dye that turns transparent when heated up, revealing a third layer of colored ink underneath. Because the layers are printed with varying thickness from "0%" to "100%", parts of them become yellow before others, creating a bargraph effect that varies with the current applied, the battery's body itself sinking the heat produced by the conductive ink.' Pretty cool stuff."

84 of 327 comments (clear)

  1. Text of Page by Anonymous Coward · · Score: 4, Informative

    The amazing Linux Duracell CPU load monitor
    Turning an AA on-battery tester into a CPU load monitor for Linux

    You probably know those onboard testers found on Energizer and Duracell batteries : press the two white dots printed on the wrapper, and magically the battery's state appears on a yellow bar. No need for a separate battery tester, everything is included on the battery itself. While not very precise, it's good enough to know if a battery is brand new, so-so, or completely dead.

    These throwaway testers are quite clever : they use a layer of conductive ink that heats up when an electrical current runs through it, in combination with a layer of thermally-activated dye that turns transparent when heated up, revealing a third layer of colored ink underneath. Because the layers are printed with varying thickness from "0%" to "100%", parts of them become yellow before others, creating a bargraph effect that varies with the current applied, the battery's body itself sinking the heat produced by the conductive ink. Informative details about those testers can be found here :

    HowStuffWorks
    The Duracell Battery Tester
    AA Battery Tester

    Here are instructions to turn such a tester into a not-so-precise analog display to monitor the CPU load on a Linux system, controlled by a serial port.

    What you need
    # An AA Duracell battery with a tester. Energizer testers should work too, but I haven't tried. I got a pack of Duracell Ultra M3 batteries, product code LR6-MN1500.
    # 1 x 3V power cube
    # 1 x 2 KOhm resistor
    # 1 x 4.7 KOhm resistor
    # 1 x 10 KOhm resistor
    # 1 x 4N25 or CNY17 optocoupler
    # 1 x BC547A or 2N2222A transistor
    # 1 x TIP41C transistor
    # 2 x 1N4004 diode
    # 3 x ON/OFF switche
    # 1 x female DB9 connector
    # 1 x large-ish breadboard
    # 1 x clear plexiglas CD case
    # 100 x patience
    Instructions to make the display
    Cleanly unwrap the tester off the AA battery. Be careful not to pull on any one side too hard, or you'll warp it and it'll be that much harder to connect on the breadboard. Personally, I lift both corners, gently unroll it on 3/4 mm, then use a knife and my thumb to finish taking it off the battery with an even pull. Here's what it should look like, before trimming the warped bit of the packaging :

    Here's the really hard bit : making a somewhat reliable connection between the tester's conductive ink points and the rest of the circuitry. To do that, place the tester on the breadboard, near the upper edge, and mark out precisely the breadboard holes the wrapper's white dots fall on. Spend some time aligning the right white dot (on the "minus" side), as the patch of conductive ink there is very thin and right on the edge of the tester. The dot on the left ("plus") side is less problematic.

    To make the connectors, solder bits of "hairy" copper wire (like that found on common mains electrical cords) in the holes you marked, and leave the "hairs" sticking out where the tester will be installed. They'll help make a correct electrical contact with the tester's conductive ink. Cut out a piece of clear plexiglas from the CD case, tape one edge to the upper edge of the breadboard, and punch a small hole near the bottom edge. This makes a window to hold the tester and press it flat against the breadboad and the connector.

    Solder the circuit's components at the bottom of the breadboard, under the window (there should be about 3 cm worth of breadboard left there). Here's the circuit's schematic:

    Notice the 2 switches around the 1N4004 diodes : those diodes are there to reduce the voltage fed to the tester, but depending on the individual tester and the quality of the contacts with the conductive ink, you might need to overload the tester a bit to reach 100%, or make it more reactive. With the switches, you can short one or both diodes, adding 0.6V per shorted diode.

    Once the circuit is done, feed it 3V and close all the switches. Then carefully align the tester on

    1. Re:Text of Page by ttldkns · · Score: 5, Informative

      mirror with the pictures...
      here

      --
      How many computers are too many?
  2. A pity... by HTH+NE1 · · Score: 5, Interesting

    A pity that Duracell seems to not be interested in putting these testers on their batteries or in their packaging anymore. Saw a whole rack expiring March 2010 with not a single tester.

    --
    Oh, say does that Star-Spangled Banner entwine / The myrtle of Venus with Bacchus's vine?
    1. Re:A pity... by Anonymous Coward · · Score: 5, Interesting

      I think that Energizer is putting them on their E2 batteries only.. I noticed the same thing last time I was buying batteries.

    2. Re:A pity... by KUHurdler · · Score: 5, Insightful

      I think its a pity for them too. Theres no quicker way to drain a battery than to use one of those little testers. Those little things would have you buying more new batteries in no time. Duracell should know that too.

      --
      Fix Your Own TV - RiddledTV.com Avoid the Landfill
  3. Ah-may-zing by clifgriffin · · Score: 5, Funny

    So that's how they does it. I personally use my mouth. I'm sure I'll regret it someday.

    1. Re:Ah-may-zing by proj_2501 · · Score: 5, Funny

      What the hell kind of tongue do you have that can hit both ends of a AA battery?

    2. Re:Ah-may-zing by jon787 · · Score: 2, Funny

      My friend adam used his finger to measure the power left in a VersaPak battery (used in black and decker cordless tools) he regretted it.

      --
      X(7): A program for managing terminal windows. See also screen(1).
    3. Re:Ah-may-zing by RealityMogul · · Score: 2, Insightful

      My cousin once put two 9-volts together pos->neg. Blew up in his face. He didn't do that again. Duracell or Enegizer (don't remember which) did a presentation in his school about battery safety shortly afterwards.

    4. Re:Ah-may-zing by Short+Circuit · · Score: 5, Funny

      My brother took one of those industrial-grade (you know, without the current limiter) 9-volts and put it on his tongue. He told me it didn't un-curl for several minutes.

    5. Re:Ah-may-zing by Short+Circuit · · Score: 2, Funny

      I think KISS sells them.

    6. Re:Ah-may-zing by TechnoVooDooDaddy · · Score: 5, Funny

      geeks need any advantage we can get with the ladies you know....

    7. Re:Ah-may-zing by jbuck · · Score: 5, Funny
      as a kid, I found testing batteries with my tongue was pretty efficient. And as a kid, the telephone line seemed to be a pretty low voltage application- even caller ID units needed a seperate 1.5v battery to get power, so how strong could the telephone line be, right? Plus the contacts were close enough to test with my tongue so why not? I needed to see if the line was live...

      WOW! now THAT was a JOLT! I would NOT recommend it to anyone. Save your tongue and find a telephone line tester!

      as a geek, you live and learn, you live and learn, I guess.

      --
      -whoa, I'm jones'ing for a sig right about now...
    8. Re:Ah-may-zing by Anonymous Coward · · Score: 5, Funny

      You are lucky it didn't ring at the same time.

    9. Re:Ah-may-zing by Anonymous Coward · · Score: 2, Funny

      Sometimes I wonder if there's one guy out there who's the brother or cousin of about a million different people, and he is the source of all urban legends, because almost every often-repeated story about somebody doing something collosally stupid in an entertaining way begin with "my cousin" or "my brother."

    10. Re:Ah-may-zing by Lehk228 · · Score: 2, Interesting

      I do know that Industrial batteries are strong, never shocked myself with the one i had back in 7th grade, the thing outlasted regular 9-volt batteries by a factor of 3 or 4... and it put out enough current even when it was weaker to outperform a regular 9 volt after it was below 95%

      --
      Snowden and Manning are heroes.
    11. Re:Ah-may-zing by Anonymous Coward · · Score: 3, Funny

      You forget that in the southeastern United States just about everyone is a cousin.

    12. Re:Ah-may-zing by AhBeeDoi · · Score: 2, Funny

      Images of Gene Simmons keep popping into my head. I'm afraid to go to sleep now.

    13. Re:Ah-may-zing by Rolo+Tomasi · · Score: 4, Informative

      No kidding. Ring voltage is around 90Vac at some non-trivial current. That would have been some deep-fryed tongue.

      --
      Did you know you can fertilize your lawn with used motor oil?
    14. Re:Ah-may-zing by netringer · · Score: 4, Funny
      My cousin once put two 9-volts together pos->neg
      BEGIN --- Pathetic Geek story

      When I was a kid the Goldblatts department store would advertise very-very-cheap almost-dead-when-they-cross-the-dock loss leader imported 9 volt batteries for 9 cents.

      I bought two 10 pack boxes of them for a couple bucks, rusehd home, and connected them in series by snapping them together + to - to + ... in a lattice arrangement.

      Once I had all 20 together... and knowing that I had, *gasp* 180 VOLTS! at my disposal ... I connected some wires to from the ends to a 25 watt 117VAC household light bulb and marvelled as it lit up brightly and then dimmed as it drained the batteries completely in a minute or two.

      END --- Pathetic Geek story

      --
      Ever dream you could fly? Get up from the Flight Sim. I Fly
    15. Re:Ah-may-zing by Lifewolf · · Score: 4, Funny
      Plus the contacts were close enough to test with my tongue so why not? I needed to see if the line was live...

      Once, many years ago, a friend and I were in his parent's basement racing slotcars. He put his head on the track so he could watch his car zoom away, and the track lightly shocked his ear. Of course, as a regular test-the-9-volt-on-his-tongue kind of kid, he immediately had to try sticking his tongue to the track. Idiot.

      --
      "Be Happy or Die." -- AoN
    16. Re:Ah-may-zing by MrAngryForNoReason · · Score: 4, Funny

      It helps to tell yourself the current makes it sterile and non gross as you make out with the battery.

      Am I the only one that read that as "makes you sterile"?

    17. Re:Ah-may-zing by kableh · · Score: 2, Informative

      Then you've never stripped a live telephone wire with your teeth when you were a kid.

      I assure you you're wrong about the voltage. Cisco has 48VDC options on much of their equipment for a reason.

    18. Re:Ah-may-zing by Jotham · · Score: 3, Informative

      uh, a lightbulb isn't AC -- its just a big, simple resistor that heats up and gives off light. It doesn't care which way the current flows through it.

    19. Re:Ah-may-zing by mister+matt · · Score: 2, Informative

      No, I am not an idiot.

      In the context of the discussion, size doesn't matter. because the internal resistance differences from 9V battery to 9V battery make for a insignificant difference in the amount of current passing through one's tongue. At a load of 30kohms (like i measured on my tongue), a 9V battery (even a "consumer" one) will not drop more than a few hundreths of a volt. Try it and see.

      It's true, AC is much more dangerous than DC, I was oversimplifying.

      >So no, there is zero chance of getting
      >electrocuted from licking a 9V battery.

      Where did I say there was?

      As far as being killed from a 9V battery, consider this:

      http://www.darwinawards.com/darwin/darwin1999-50 .h tml

      In this case, it is DC, but consider that at the sudden application of the current, even DC creates high frequency transient that could disrupt one's heart, similar to the way AC does. That my theory of what happened in this rare instance.

    20. Re:Ah-may-zing by adamjaskie · · Score: 2, Funny

      It was only 3.6 volts...

      --
      /usr/games/fortune
    21. Re:Ah-may-zing by richie2000 · · Score: 2
      Mr Fluke is your friend.

      Once in college, the moron (for many, many reasons) physics teacher pulled out a fist-sized capacitor and dared one of the pupils up front to lick the terminals. I just barely managed to stop him by ripping the capacitor out of the teacher's hands and stick it to the metal crank of the pencil sharpener instead. It fused to it. Everyone suddenly went very, very pale.

      --
      Money for nothing, pix for free
  4. No more for Duracell or others? by 192939495969798999 · · Score: 3, Interesting

    I haven't seen a tester for months, on any kind of battery. I don't think they are being made anymore, does anyone else know otherwise? I thought a gauge like that would be great for cpu physical temperature as well.

    --
    stuff |
    1. Re:No more for Duracell or others? by superpeach · · Score: 4, Informative

      They dont seem to have them on Duracell plus, but Duracell M3 batteries do. I guess its just something you get with the top of the range types :)

    2. Re:No more for Duracell or others? by teeker · · Score: 4, Informative

      err...this is a project to show system load, not temperature.

      Plus, since when is a clever hack not worthwhile just for the sake of doing it? I think it's neat. Next to worthless, but definitely neat.

      --
      teeker
    3. Re:No more for Duracell or others? by srvivn21 · · Score: 2, Informative
      Quote the poster:
      How did this post get modded up? Read the article!

      This isn't a temp sensor. It is measuring electrical current, not heat.

      Quote the article:
      ...they use a layer of conductive ink that heats up when an electrical current runs through it, in combination with a layer of thermally-activated dye that turns transparent when heated up, revealing a third layer of colored ink underneath.


      Perhaps it could be used as a temperature guage after all?
  5. Wow by Anonymous Coward · · Score: 4, Funny

    They must be using the batteries to run the site. Slashdotted already.

  6. Instantly slashdotted by Anonymous Coward · · Score: 5, Funny

    less than 5 posts and the French webserver has already surrendered.

    1. Re:Instantly slashdotted by Anonymous Coward · · Score: 5, Informative

      boo ya! I knew I made the right choice opening the article instead of going for first post! HA HA I can see all the pretty pictures, I WIN IT!

      ps the admin is pcoupard at easyconnect.fr, so send him money to buy a bigger webserver. Or if you just want to mock the french.

      And more importantly, the link to download the driver for the monitor is http://webperso.easyconnect.fr/om.the/web/duracell _cpumon/download/duracell_cpumon-0.0.1.tar.gz, which of course will already be slashdotted by the time you click on it.

  7. I hope he doesn't have one of those on the server by Peeet · · Score: 5, Funny

    that's hosting that website, or this could be the first slashdotting to start a small fire.

    Are you happy now? Y'all have slashdotted a battery.

  8. Marketing Genius by Speare · · Score: 5, Interesting

    When those little battery testers first came out, I thought it was pure marketing genius. Not for the convenience, but for the self-depleting consumable. It ranks right up there with Caller ID.

    "Here's a battery which you can wear out, even before you put it in your flashlight! You don't have to worry about shelf-life or temperature anymore, just squeeze the ends and you have a dead battery. No muss, no fuss, just two minutes from package to trashcan."

    The Caller ID, in its original implementation, though... sheer brilliance. "Let's make them pay to see the information that's already sent to the the switchbox! And if they don't like that, make them pay to HIDE the information on the switchbox. But that doesn't really hide it, it just flags it, so make them pay to see the HIDDEN information, or make them pay to REALLY hide it. We can go on like this forever."

    --
    [ .sig file not found ]
  9. How about a /. effect monitor? by ackthpt · · Score: 3, Insightful

    It's neat, but rather than skin a battery, I wonder if those same things which were, and maybe still are, in the plastic packaging would be easier to work with

    --

    A feeling of having made the same mistake before: Deja Foobar
  10. A Mirror by trp642 · · Score: 5, Informative

    ... to keep our French friend's bandwidth down...
    http://home.cfl.rr.com/fnords/duracell_cpumon/
    I hope my ISP doesn't kill me... ;)

  11. Mirror by E1ven · · Score: 4, Informative

    In case the site shuts down under the load, I've mirrored the page (including the Video,) to our SQ7.org project server.

    Mirror

    Good luck, and a cool project. A Hacker in the coolest sense of the word.

    --
    Colin Davis
  12. When I was a kid by Anonymous Coward · · Score: 5, Funny

    The only battery affordable meter we had was for 9 volt batteries. And it was your tongue! And we liked the small spark it gave you to tell you it was working!

    1. Re:When I was a kid by ZHaDoom · · Score: 5, Funny

      I remember putting two nine volts together and placing them in my sock. Keeped my feet warm while I walked uphill(both ways) to school and back in 6 feet of snow.

      --
      War isn't about who's right. It's about who's left.
    2. Re:When I was a kid by dustmote · · Score: 2, Funny

      Wow, that seems like an interesting method of beating the heat. Correct me if I'm wrong, but wouldn't that also give you a chance of much badness happening in your general foot area?

      --


      -1, "1337" speak
    3. Re:When I was a kid by ZHaDoom · · Score: 2, Funny

      Only a 1" x 4" area. The rest is fine.

      --
      War isn't about who's right. It's about who's left.
  13. The obvious puns by thewiz · · Score: 5, Funny

    "His design is utterly revolting!"
    "Shocking!"
    "If I add more power, can I overclock it?"
    "An electrifying hack!"
    "More power to him."

    --
    If "disco" means "I learn" in Latin, does "discothèque" mean "I learn technology"?
    1. Re:The obvious puns by Anonymous Coward · · Score: 5, Funny

      Ohm my, watt a clever hack.

    2. Re:The obvious puns by aanand · · Score: 2, Funny

      "Does it play Ogg?"

  14. Useless on a quickly varying load. by stephenisu · · Score: 5, Insightful

    I find this to be amusing and all, however pretty pointless. These strips take almost a full two seconds to register a full change. Spikes in usage (good to know sometimes) will be completely missed. Plus I am willing to bet you need to recalibrate it often if your room temp changes by more than a few degrees.

    I would have RTFA, however it seemed to be down at the moment.

    --
    Sigs? We don't need no stinking sigs!
    1. Re:Useless on a quickly varying load. by MoonBuggy · · Score: 4, Funny
      Your points are valid, but to quote the article:
      There you have it : the most imprecise, slow, power-hungry, finicky and unreliable CPU load monitor in the world. Aren't you happy ? :-)
    2. Re:Useless on a quickly varying load. by babyrat · · Score: 2, Informative

      spikes in CPU usage generally don't matter when you are monitoring general CPU load. Spikes are expected, and they happen, and if the processor is mostly running at an acceptable load (like under 50%) they don't matter. If the spikes get frequent enough to have an effect on the temperature of the monitor, then they are probably something to be concerned about. You are correct in that it's good to know about them 'sometimes' but most of the time it isn't.

      The load avg. on unix machines filter out 'spikes' - so does this device.

      Now if you were using something like this on anything important, I'd say you are crazy, but it's a very interesting concept.

  15. Or you can use software... by moquist · · Score: 3, Informative

    such as Gkrellm, which is available for Linux, FreeBSD, Mac OS X, Net BSD, OpenBSD, Solaris, and Windows... if you install gtk, gdk, glib, etc.

    But a cheap hardware solution *is* pretty cool.

    Now, if you could hook one of those Duracell indicators up to your date for the evening...

    1. Re:Or you can use software... by ktulu1115 · · Score: 3, Interesting

      Actually I was thinking a mix of the two. Take his project but remove the el-cheapo duracell battery tester and replace with a VU meter or something similiar. A schematic similar to this would work, although either the voltage supplied would have to be upped or some resistors need to be changed on that schematic, either way it would work and actually look somewhat decent (and respond in realtime too!)

      Put it on top of your stereo or in your cabinet and be the uber-geek (mine's right next to my PC so it makes sense :) Apologies for the image, it a few years old - when I used to actually run Windows.

      --
      # fuser -v /dev/attention | grep work
      #
  16. Missing tester on batteries by derphilipp · · Score: 2, Interesting

    Many of you complain about the missing tester on newer batteries - but be honest
    Who ever used these things ?
    I for one did't and I don't know anyone who did.
    Whats the point in measuring the power of throw-away batterys anyway ? On rechargeable batterys this would be useful but not on throw-aways....

    --
    Spelling mistakes: My is english spoken not tongue of mother.
    1. Re:Missing tester on batteries by stephenisu · · Score: 2, Insightful

      When you are cussing and swearing at your kids new christmas toy that doesn't want to work, and you need to know if its the batteries or the toy, but you are at the grandparents and have no voltmeter, they come in handy for knowing if you need to go and buy new ones.

      --
      Sigs? We don't need no stinking sigs!
  17. Old School ... by SuperDuG · · Score: 4, Interesting
    ... Back when I was a kid slashdot used to have all sorts of crack pot stories where if it involved a computer or linux in some way it was posted to slashdot ... thats the way it was and we liked it.

    This is exactly what brings me to the nostalgia of what I like to see on slashdot, a story about some guy who attached some wires to a battery tester and then made a LINUX program to pop out the correct varying voltage to display on the battery itself.

    This is cool, and you want to know why? Its innovative, sometimes we go so long and things start to get stagnant that it takes these wonderfully clever people to come up with a new innovative way to do something. Is it practical, well no, but that doesnt mean its not cool.

    I for one would like to see more things like this and an SCO category so I can start to delete those stories from the front page. I like the true hacker stories, its fun to see how people are innovative. Really was something pleasant to read.

    Good Show!!

    --
    Ignore the "p2p is theft" trolls, they're just uninformed
    1. Re:Old School ... by FurryFeet · · Score: 2, Offtopic

      For someone who has been here a long time, you don't seem to have mastered Slashdot. There IS a SCO category. It is just called "Caldera".
      So, go here .
      Go down to "Exclude stories from the homepage", and under "Topics" check the box next to Caldera.
      Then go all the way down and click "Save".
      There. No more SCO stories for you.

  18. Neat. But WHY? by wowbagger · · Score: 5, Insightful

    OK, this is neat, but WHY?

    This same circuit could be adapted to:

    Vary the brightness of a small light bulb.
    Vary the speed of a small motor.
    Drive an old-style swing needle meter.
    (Variant of above) Drive a tachometer.

    Heck, why not interface to a slot-car and have it go faster the higher your load average is?

  19. System Monitor by milgr · · Score: 3, Insightful

    For cpu load average, I run System Monitor. It displays a pretty bar graph in the panel at the stop of my screen.

    Cost for running system monitor: $0.0
    Time for setting it up: 00:00:30

    Cost for Duracell load monitor: $9.95
    Time for setting up: 04:21:23

    --
    Where law ends, tyranny begins -- William Pitt
    1. Re:System Monitor by Shut+the+fuck+up! · · Score: 5, Funny

      Cost for running system monitor: $0.0
      Time for setting it up: 00:00:30

      Cost for Duracell load monitor: $9.95
      Time for setting up: 04:21:23

      Slashdotting the French: Priceless.

    2. Re:System Monitor by dk.r*nger · · Score: 2, Funny

      There are some things in life, that are simple, obvious and easy to do.

      For everything else - there's Slashdot.

  20. you're no genius by Anonymous Coward · · Score: 5, Informative

    "Here's a battery which you can wear out, even before you put it in your flashlight! You don't have to worry about shelf-life or temperature anymore, just squeeze the ends and you have a dead battery. No muss, no fuss, just two minutes from package to trashcan."

    what are you talking about?

    You can't drain the whole battery with a voltage tester in two minutes. It would take half an hour if you just shorted it out to drain it.

    OBVIOUSLY, the tester is there to check to see if those batteries you threw in the drawer months ago are still good.

    DUH

    1. Re:you're no genius by Anonymous Coward · · Score: 2, Informative

      Alkalines drop off very fast at the end if life, so it's not the problem you seem to think it is. I'm not sure what your "20%" means. From looking at the pictures of the back of the gauge and voltage drop off curves, I'd say it's pretty fair. For a real drop off cursed, check here.

  21. Temperature-sensitive Leucodyes by G4from128k · · Score: 5, Interesting

    The activiation temperature of battery testers is a pleasantly toasty 100-120 F.

    --
    Two wrongs don't make a right, but three lefts do.
  22. that reminds me of a funny story... by morcheeba · · Score: 5, Funny

    one day I noticed the icemaker in our freezer made the sound it does before it drops the cubes into the bucket. So, I looked in to see if I could watch it work... then I noticed that an extra metal tube went under the ice cube mold. I thought, wow, that's kinda neat - they must circulate a little extra freon through there to make sure the cubes are super-cold*. So, I decided to touch it to see how cold it was. It turns out that it wasn't a cooler, but a heating element that was used to slightly melt the edge of the cubes to release them from the mold. And it was very hot.

    That's how I burned my finger in a freezer.

    (* I was thinking that didn't make too much sense because I knew icemakers were often add-on features, and replumbing the freon would be too complicated to do for an accessory)

  23. Re:Wow by fafaforza · · Score: 2, Funny

    Hope he didn't build a set to measure his throughput. It might overflow and explode.

  24. Re:Too Much Time by mph · · Score: 5, Funny
    My god I wish i had that much time on my hands. I barely have time to eat when I get home before I go to bed...
    Of course, eating and sleeping fall somewhere below "posting to Slashdot" on the priority list.
  25. Tongue as battery tester. by Futurepower(R) · · Score: 5, Funny

    You put a wet finger on the negative end and touch the postive end with your tongue. For 1.5 volt batteries only. Don't try this on 90 volt batteries.

    1. Re:Tongue as battery tester. by Fishstick · · Score: 2

      I used to test 9V "transistor" batteries this way. Dip the tip of your tongue across both terminals, that little tingle tells you the battery still has juice.

      I've never had the opportunity or incliniation to attempt this oral test method on any of the cylindrical styles (AAA - D)

      BTW, what ever happened to single-A and B batteries?

      AAA - little tiny remote batteries
      AA - smaller, walkman sized
      C - medium, tape decks, etc (good for hiding in your fist to hit someone)
      D - full-size flashlight size

      --

      There is much cruelty in the universe, John.
      Yeah, we seem to have the tour map.

    2. Re:Tongue as battery tester. by Jahf · · Score: 2, Funny

      90 volts? That would fry some braces :)

      --
      It is more productive to voice thoughtful opinions (reply) than to judge (moderate) others.
    3. Re:Tongue as battery tester. by stratjakt · · Score: 5, Funny

      When's the last time you saw a C cell used in anything besides a dildo?

      I'm serious.

      Thats the only reason they exist.

      --
      I don't need no instructions to know how to rock!!!!
    4. Re:Tongue as battery tester. by edhall · · Score: 2

      Don't be silly. Kid's toys use mountains of them.

      -Ed
    5. Re:Tongue as battery tester. by Fishstick · · Score: 3, Funny

      you're doing something wrong - mine uses D-cells ;-)

      --

      There is much cruelty in the universe, John.
      Yeah, we seem to have the tour map.

    6. Re:Tongue as battery tester. by Necrobruiser · · Score: 5, Funny

      You really should reconsider what "toys" your kids are playing with... ;)

      --
      "I planned within my means and got a fixed rate mortgage, so where's MY bailout?" -cafepress
  26. Battery testers.. by eples · · Score: 3, Interesting

    You used to be able to purchase those strips for a buck, although they were much better than the lousy ones they stuck onto the batteries.

    --
    I'm a 2000 man.
  27. Another electronics idea by bigberk · · Score: 4, Interesting

    Here's something I did to help visually monitor my CPU temperature (and it doesn't require any software). You could extend it to monitor the temperature of any part that tends to overheat.

    Grab yourself a basic comparator such as the LM339 and a temperature sensor such as the LM135. Make a circuit that compares the temperature sensor's voltage to a pre-defined threshold, and lights the LED if the temperature rises too much. The 'Typical Application' section of each datasheet pretty much shows you exactly how to wire up the parts.

    You can put this circuit in your computer's case (run it off a spare +5 voltage connector) and use a spare LED you find, like the Turbo light ;)

  28. More useful than measuring load... by peyote · · Score: 2, Interesting

    ...would be measuring the battery life of my laptop. (Stupid APM kernel oopses.) Just think: using a battery tester to... test... a battery!

    1. Re:More useful than measuring load... by ShadowDrake · · Score: 2, Interesting

      If you know the battery pinout, I could see connecting your preferred style of voltimeter across it. Ideally with a switch, so you don't drain it when you aren't resding the gauge.

      I note that some batteries (like the ones in my old Toshiba 486) had + and - clearly marked on the unit

      --
      It's just like a fascist dictatorship, without the punctual rail service!
  29. Netcraft has confirmed: Duracell is dying by KLP-2002 · · Score: 3, Funny

    It is now official - Netcraft has confirmed: Duracell is dying

    Yet another crippling bombshell hit the beleaguered Duracell community when
    recently IDC confirmed that Duracell accounts for less than a fraction of 1
    percent of all servers. Coming on the heels of the latest Netcraft
    survey which plainly states that Duracell has lost more market share, this
    news serves to reinforce what we've known all along. Duracell is collapsing
    in complete disarray, as fittingly exemplified by failing dead last in
    the recent Sys Admin comprehensive networking test.

    You don't need to be a Kreskin to predict Duracell's
    future. The hand writing is on the wall: Duracell faces a bleak future. In
    fact there won't be any future at all for Duracell because Duracell is dying.
    Things are looking very bad for Duracell. As many of us are already aware,
    Duracell continues to lose market share. Brown ink flows like a river of
    shit.

    Let's keep to the facts and look at the rumors.

    Cum laude Theo states that there are 7000 users of Duracell. How
    many users of Caldera are there? Let's see. The number of SuSe versus
    Caldera posts on Usenet is roughly in ratio of 5 to 1. Therefore there
    are about 7000/5 = 1400 Caldera users. Connectiva posts on Usenet are about
    half of the volume of Caldera posts. Therefore there are about 700 users
    of nig cum. A recent article put TurboLinux at about 80 percent of the Duracell
    market. Therefore there are (7000+1400+700)*4 = 36400 TurboLinux users.
    This is consistent with the number of TurboLinux Usenet posts.

    Due to the troubles of SCO, abysmal sales and so on, TurboLinux
    went out of business and was taken over by SCO who sell another
    troubled OS. Now SCO is also dead, its corpse turned over to yet
    another charnel house.

    All major surveys show that Duracell has steadily declined in market share.
    Duracell is very sick and its long term survival prospects are very dim. If
    Duracell is to survive at all it will be among OS hobbyist dabblers. Duracell
    continues to decay. Nothing short of a miracle could save it at this
    point in time. For all practical purposes, Duracell is dead.

    Fact: Duracell is dead

    --
    GNAA rocks - cumming to your town soon!
  30. battery/CPU meter by RY · · Score: 2, Funny

    I wonder if the CPU meter is showing max load now?

  31. You answered your own question by ackthpt · · Score: 2, Funny
    And why the heck is anyone doing a dumb project like this? I mean sure, it's neat, but its entirely impractical.

    Next!

    --

    A feeling of having made the same mistake before: Deja Foobar
  32. You answered your own question.... by gosand · · Score: 3, Insightful

    OK, this is neat, but WHY?

    This same circuit could be adapted to:

    Vary the brightness of a small light bulb.
    Vary the speed of a small motor.
    Drive an old-style swing needle meter.
    (Variant of above) Drive a tachometer.

    Heck, why not interface to a slot-car and have it go faster the higher your load average is?


    I am sure you can take his code and modify it to do just that if you like. (and that answers part of your WHY question). The other part is just "because". This is true hacking.

    I do like the idea of an analog gauge to show the CPU load.

    --

    My beliefs do not require that you agree with them.

  33. in case you can't get to their site anymore... by Anonymous Coward · · Score: 3, Funny

    For those of you who noticed the site's not available, there's a little bar graph on their server.

    Here's a live feed:

    E |==============X| F

  34. Probably because the public isn't entirely stupid by SuperBanana · · Score: 4, Insightful
    A pity that Duracell seems to not be interested in putting these testers on their batteries or in their packaging anymore

    I'd guess it's because people weren't as stupid as the battery companies thought they were. Most people know full well the strip works by heating up, and that wastes the power of the battery.

    On top of that, it's redundant; most consumer devices have battery gauges, the gauge can't be used when it's in the device, and when it runs out- you usually either have spares, or a quick trip to the quik-mart fixes the problem. That means that something that cost money to put on the battery was now raising the cost on the shelf versus the competition, or eating into the profit margin.

    Not to mention, non-rechargeable batteries are useless to most product designers, because the devices are way too a)small and b)power hungry.

  35. Re:Changes... by Ancient_Hacker · · Score: 2, Informative

    Hmmm, the circuit looks like it will work, but it's rather overdone... You don't need the optoisolator, or the first transistor, just use a plain old 3 amp MOSFET. And then you don't need the diodes or the switches and you can lower the supply voltage to 1.5 volts, as the MOSFET is a near-perfect switch. I havent tried it yet, but it looks like you can replace the whole shebang with a 100K resistor, a power MOSFET, and a 1.5 volt D cell.

  36. Get some thermochromic ink by ColaMan · · Score: 2, Funny

    If I was a heatsink manufacturer, I'd .....

    1) Write on the side of your CPU heatsink the words "If you can see this , it's too hot!"

    2) Paint that side with black thermochromic ink that changes temperature at 60 degrees C.

    3) Profit!!!

    Or, as the temperature drops from the bottom to the top of the heatsink, you could put things like "cool..." "warm..." "warmer..." "Hot..." "FUCK!" up the side of the heatsink. One glance and you'd know. Handy for those clear cases ;-)

    --

    You are in a twisty maze of processor lines, all alike.
    There is a lot of hype here.