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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."
The amazing Linux Duracell CPU load monitor
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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
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?
So that's how they does it. I personally use my mouth. I'm sure I'll regret it someday.
clifgriffin > blog
They must be using the batteries to run the site. Slashdotted already.
less than 5 posts and the French webserver has already surrendered.
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.
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."
[
... to keep our French friend's bandwidth down... ;)
http://home.cfl.rr.com/fnords/duracell_cpumon/
I hope my ISP doesn't kill me...
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
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!
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 :)
"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"?
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!
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
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?
www.eFax.com are spammers
"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
The activiation temperature of battery testers is a pleasantly toasty 100-120 F.
Two wrongs don't make a right, but three lefts do.
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)
HIV Crosses Species Barrier... into Muppets
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.
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.
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 ;)
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
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.
Please help metamoderate.