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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?
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...
So that's how they does it. I personally use my mouth. I'm sure I'll regret it someday.
clifgriffin > blog
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 |
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."
[
Now we can all buy more bootleg $1.00 packs of batteries from vendors riding the subways to test our CPU loads!
MoFscker
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
... 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
So you rig your webserver to put out an increasing electrical charge as hits go up, you then have a nice visual indicator of when you're being /.'ed, just like their French page.
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 use a layer of conductive ink that heats up when an electrical current runs through it Now I know why I got first degree burns on the tips of my fingers from using the tester too long.
The duracell bunny is destroyed by the slashdot holy handgranade, and withing 3 posts. Oh the sweet irony
for the last time people, I am "frodo from middle eaRTH", not "middle eaST".
"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!
... I guess those French servers just gave up when they saw all those requests coming. badda bing
Sorry about that.
I can probably guess why they don't exist any more, although this is just a guess. It cost too much time and money to put the mechanism that measures life-left into each individual battery, for free.
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...
I just found the most amazing tool to do the same thing as this. I know it's a lot more complicated but I think us slashdotters can figure it out. "top" or for you windoze people, ctrl-shift-esc. Lots o' luck to ya.
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.
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
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
If you die, can I have your sister?
"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
Hope he didn't build a set to measure his throughput. It might overflow and explode.
This is OK, but the various Linux LCD projects make for cooler displays.
h p3
Check out:
http://lcdproc.omnipotent.net/screenshots.p
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.
GTRacer
- Nice Python ref, BTW
Defending IP by destroying access to it? That makes sense, RIAA/MPAA. Go to the corner until you can play nice!
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.
Man, I hate when I forget to unshort my pins and I get majorly fried. It totally sucks...
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 ;)
If the batteries died, you'd be getting a "connection refused" error.
tasks(723) drafts(105) languages(484) examples(29106)
...would be measuring the battery life of my laptop. (Stupid APM kernel oopses.) Just think: using a battery tester to... test... a battery!
Can somebody make an IC out of that... don't wanna carry the extra baggage!
My other dog is a Wienerschnitzel.
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!
I wonder if the CPU meter is showing max load now?
Then you can get a story posted to slashdot about your cool hack, too. I would love to see that CPU slot-car thingie. The tachometer is a good one, too. Can you make it make the sound of a Ferrari reving?
Next!
A feeling of having made the same mistake before: Deja Foobar
Some of them turn bright orange. Fun for all, unless you like math.
I just checked my cordless mouse, and no tester.
These are the original batteries that came with the Apple bluetooth mouse, and are only a few months old (the mouse hasn't been out that long); expiration date 2013. Are yours older? Or did apple buy special OEM batteries (the mouse has a low-batt sensor, so this wouldn't be necessary)?
HIV Crosses Species Barrier... into Muppets
Energizer has the bunny. Duracell has the "Trusted Everywhere" slogan.
Chip H.
Looks like they need to change the batteries on the webserver.
But... but... but... I like math AND destruction!
--- Ban humanity.
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.
"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"
The definition of ink from the Merriam-Webster Dictionary:
"1 : a colored usually liquid material for writing and printing
2 : the black protective secretion of a cephalopod"
Why is the first layer called "conductive ink"? Why not "coating" or "resin" or whatever it is? How does this stuff qualify as ink?
you see this error message: "You've reached your maximum number of comments you can post: 30 comments over 4 hours."
Awesome. Saw it for the first time today.
Now, if you could hook one of those Duracell indicators up to your date for the evening...
Already been done. =)Weaselmancer
rediculous.
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
I heard that they stopped making A and B batteries about the time vacuum tubes went out of vogue.
☠
Anyone know how quickly it responds to changes in CPU usage?
What is your penile percentile?
Yep, 48V below ground is enough to give even the most thick-skinned tongue a jolt.
☠
This isn't CPU load silly Duracell! Its just a fancy ammeter!
Lousy facepalm.
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.
if he was measuring the current with one of those VU meter displays. That would kick ass.
The backlight for the VU meter could be triggered by the serial port being active... you'd probably need to use a molex connector and pull from the system power for that though.
The only reason I could see going with the Duracell thing is if the colors matched your case or something, which I don't see here.
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
1. Neatly cut out the indicator piece. Don't leave out whole battery cover.
2. Use more than one. CPU load, CPU temp, network load, network latency, on worse networks - packet loss, maybe stuff like disk capacity or anything you really desire, that is suitable for analogue display.
3. More data channels. Either paralell or USB, or serial with UART on the other end.
4. 2 diodes and 2 switches to adjust voltage? Excuse me? Have you heard about a trimmer?
5. Load it into a neat case, maybe a front panel of the computer.
Yeah, it could look very neat. Better than a LED bargraph or a big badass analog meter. But it doesn't - it's ugly. Sorry.
45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B2
I don't think the crowd will be happy until they've slashdotted several small furry animals, a toaster, a pringles tin, and probably an alien civilisation or two.
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Comment removed based on user account deletion
Way better -- get a Griffin PowerMate (about $50). It has a glowy blue led that is software controllable (256 brightness values). Run a script that constantly sets its brightness to the current CPU load level.
Plus, the PowerMate acts like a knobby thing. I call it a mousewheel for my Wacom tablet.
Couldn't resist taking a photo of this battery I once found.j pg
Of course the battery check does not work!
www.geocities.com/carlesvilageo/durasell1.
www.geocities.com/carlesvilageo/durasell2.jpg
Reminds me of those cheesy toothbrushes that had a colored set of bristles in the center that faded over time, and when it got to a certain point of fade, it was time to replace your toothbrush.
I've never used one, but I imagine that when it actually hit the alleged "replace now" mark, the toothbrush was probably still just fine. I don't even know if they still make them.
-- Give him Head? Be a Beacon? :P)
(If you can't figure out how to E-Mail me, Don't.
The parent post has really got me pissed off, it is so completely irresponsible that it's beyond words. Think of the impressionable youngsters who might be reading this site and decide to imitate his behavior. Hello??
I've been saving a bunch of old batteries for toxic waste disposal (you're not supposed to toss em in the trash) so I suspect I have a number that still have the little strip on them. Time to reuse them prior to recycling...
They probably still make them since they're fool-proof, but the question is do they have them in the right range? (Most CPUs run a bit hot for live fish.) Try your local fish-hobby place.
One line blog. I hear that they're called Twitters now.
Bonnnjjjjooourrrrrrrr, ya cheese-eating surrender monkeys! Meet Slashdot!
Facts do not cease to exist because they are ignored. - Aldous Huxley
Course, it could be different for geeks...toys like that are there to be used every 5 minutes!
Facts do not cease to exist because they are ignored. - Aldous Huxley
you and your pedantic fucking submission cunts
Welp.. happy birthday to me. happy -1 offtopic to me... but I have karma to spare.
2004-02-11 17:58:04 Duracell Battery Tester CPU Monitor (articles,hardware) (rejected)
Even better, here in germany we have fall-back power for ISDN lines. If you do give it 230Vs from mains, it gets them via the telephone live!! :)
Figured that out the hard way during installation of such an ISDN line at home...
I imagine that when it actually hit the alleged "replace now" mark, the toothbrush was probably still just fine.
You imagine correctly. It's a totally useless "feature" which makes the brush-heads more expensive, and it's trying to fool you into believing that you need to buy a new brush-head just because "the blue is gone".
AFAIK they still make them.
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.
Don't be so sure of that. I asked several of my friends, and not one of them knew that it wastes the battery to test it. I've never thought about it, and no one ever told me before now.
several small furry animals
Like this??
"mirror with the pictures...
here [ttldkns.ath.cx]"
Wow1 I can see were the probes go.
This is probably the sort of thing that should go on halfbaked, but why do we only see AA/AAA batteries with a circular cross section? I know it's the standard, but plenty of battery compartments have no guides or anything that protrudes into the area that would be used by a square cross section, at least for half of the battery. Let's say that a AA's cross section is -- warning, ASCII art -- (). We could have extended life AAs that are like (], or super extended life AAs that are like []. Sure, you couldn't put them in everything, but you should be able to squeeze some extra mAh from the extra volume in those devices that they would fit in.
...before someone implements a Linux-platform for Duracell-batteries.
-- ess
After working with a friend of mine who works in my home town's environmental agency, I won't bother with "sending batteries for recycling". He told me that they pack them together and then dump them in the same landfill...
What the f*** does that mean? :)
You've got mail. Pattern baldness. - Crow
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.
Has anyone here every seen an external, ANALOGUE CPU load/memory usage/network util gauge?
I imagine it would be a very simialr design to this but replacing the battery skin ( FUR IS MURDER PEOPLE! ) with a needle gauge.
That would look too cool!
-- If you think my attitude stinks, you should smell my fingers.
round housings are probably stronger, so maybe it is done to prevent exploding batteries. Or it might just be so much easier to produce?
Friend of mine once pee'd over electric barbwire. He didn't had to use viagra for that one day!
It sure can entertain a bored 4 yr old for quite sometime, however. It made for a small cool toy to pass time while waiting for in line for Buzz LightYear Space Ranger Spin in Orlando FL.
I'm also surprised there's no disclaimer mentioning that "Duracell" is a registered trademark of (etc). Are you trying to get sued?
my karma will be here long after I'm gone
This is possibly one of the cooler hacks (read: completely useless, but very cool) I've seen in a while.
But personally, I'd rather have the Linux be-blinkenlights hack that someone put together in the 1990's. It consisted of a C program that monitored CPU usage and sent info to the serial port, and a circuit you could build and wire to your serial port to generate a 10-bar LED bar graph that represented the load on your system.
Anyone know if this still exists anywhere?
Stinks, doesn't it? Why can't we be more like the Continent, where you can be fined or sent to prison for putting recyclable goods in the wrong bin? I'm just glad I try to avoid disposable batteries as far as possible.
Environmental concerns aside, let's follow the money and see how cheap batteries really are.
- From the mains, one kilowatt-hour costs about 6.5p.
- My petrol powered portable generator costs about 90p. per kWh when you factor in the oil which has to be mixed in with the fuel. {I probably could reclaim the petrol tax from HM Customs and Excise, since it is a non-road-going application; but apart from the words "blood" and "stone" springing to mind, I don't really want to draw their attention to me.}
- A pair of alkaline AA cells might be rated at 4Ah, making 2 * 1.5 * 4 = 12Wh. If they cost 99p {which would be a very good deal for 4Ah batteries BTW} then the cost for a full kWh would be 99 / 0.012 = 8520p = GBP85.20.
I know cheap transformer PSUs are lossy, mostly due to having to magnetise and demagnetise a hefty lump of cheap steel fifty times a second; but there's no way they could ever work out more expensive than batteries. And many modern mobile phone rechargers &c. are actually switch mode units.Je fume. Tu fumes. Nous fûmes!
Because there aren't enough ways to figure that out already.
Next we'll hear about someone making an oven that you can ping to see what temperature it is. If the latency is high, it's warm; if the latency is low, it's cold. Hooray!
Besides, who would want to use a battery tester to measure system load when it doesn't even have a themes engine or an IRC client built in?
Looking at the schematic, all you'd need to do is find one of the LM3914 *modules* (or get the chip and 10-segment bar graph LED units), and place it on the transistor output of the optocoupler. Calibrate, and you're golden.
.47uF, to allow easier readings of peaks.
Note: The 3915 and 3916 are the Log and VU displays, respectively.
I'd also add some sort of sample-and-hold capacitor, maybe a
The REAL guru on these matters can be found at http://www.tinaja.com
Reminds me of the days when I would religiously save all the spent Polaroid instant film containers. They had a flat 4" x 6" (size of Polaroid pictures) 6v battery. They've got to have enough voltage to take ten flash photos, but not all photos use flash, so they're often underused. Take them apart and you can use them for just about any DC voltage need. With ten of them you can have a very strong 6v battery for RC cars and planes, or put them in a series for higher voltages.
-=- Many seek good nights and lose good days.
Same reason almost all of your food comes in round cans instead of square ones, including soda cans and beer cans.
Explain 9V batteries then. :)
9Vs, at least when I got some radio shack ones cracked open, are actually 6 small button cells stacked together in a rectangle box with some wax to hold it together. So there, circular batteries in a rectangular box. Again.
Granted.....those button cells were actually oval, not like your CMOS batteries, but hey, you get the point.