Slashdot Mirror
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
:
:
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
... 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
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 :)
"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
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!
l _cpumon/download/duracell_cpumon-0.0.1.tar.gz, which of course will already be slashdotted by the time you click on 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/duracel
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
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?