Dan's Data letters #102
(page 2)Publication date: 3 May 2004.
Last modified 03-Dec-2011.
Have you seen Rayovac's I-C3 batteries yet?
I'm wondering if they are any better than the other rechargeable batteries out there. They claim to last up to four times longer in some devices, and to charge up to 1000 times. They also supply a charger that's supposed to charge in 15 minutes. Apparently they are NiMH, but with something in the cell itself to help deal with the heat and pressure of charging. I'm not sure if it's a sensor or what. This is supposed to help then charge faster and last longer.
Rayovac used to have a reputation for having the worst alkaline batteries out of the major brands. Not sure if that's the case this time around.
Also, what should I use for batteries in something that might sit around for a year and not get used, like an emergency flashlight in a car?
I've mentioned the I-C3 cells in passing in the past, but I sill haven't seen any personally.
The claims they make for the cells are what any rechargeable can do, except for the 15 minute charging; the "four times longer" claim is relative to alkaline cells in (very) high current devices.
Note that for low current devices, alkalines will last much better than rechargeables. NiCd and NiMH cells both "self-discharge" quite quickly, so if you leave them sitting around for a year there won't be much charge left. Year-old alkalines will still have almost as much energy left as they had when new. They're a much better choice for your emergency flashlight than NiMH or NiCd.
I think what the I-C3 cells have inside them to make the turbo charging possible is just a thermal switch - when the cells get really hot under the ultra-fast charge, the switch clicks off and breaks the circuit, allowing them to cool down (the charger's got a fan in it).
Apparently this does work quite well, though I wouldn't be surprised if it didn't actually quite finish the charge in 15 minutes - many hyper-fast chargers deliberately taper off to a much more reasonable charge rate towards the end of the charge, which is where damage can really be done to the cells. You don't know that, though, because they turn their "charging" light off as soon as they drop out of hyper-fast mode.
This is a perfectly valid strategy; a 90% charged battery's good enough for most purposes. Your "2000mAh" cell may only have as much juice in it as a fully charged 1800mAh cell unless you leave it in the charger for rather longer than the advertised time, though.
Getting back to emergency lights - for them, use lithium cells if you can. Their shelf life is unrivalled among battery chemistries with the juice to drive a flashlight.
The only consumer-battery-shaped lithiums you can get are AA cells. They're commonly available; Duracell and Energizer branded ones are in lots of stores. The catch is that their nominal voltage is 1.7V per cell, instead of the usual 1.5. In a Mini Maglite, that means you get a really bright light, because you're running the lamp at almost 1.3 times its rated power, but your bulb won't last nearly as long as your batteries.
(Regarding lithium AA shelf life - I've got a couple of Energizer lithiums that date back to at least 1993, when they were a pretty new product. The use-by date printed on them is 2003, but they've still got 3.2V between them, so there's no point replacing them with alkalines yet! They're in a laser pointer that's only had relatively occasional cat-toy use, but I wouldn't be surprised if they were still going strong another five years from now.)
There are also three volt CR123 "photo" lithium cells, as used by funky compact super-bright flashlights. These lights are great for emergencies too, but they're generally expensive enough in the first place that you're probably going to want to use them all the time, to justify the price.
There are also D-sized lithium batteries, but they're three volt as well, and so can't be used in normal flashlights expecting 1.5V cells unless you're dedicated enough to install half the recommended number of batteries, and use conductive spacers to fill the rest of the holes.
I have a Gigabyte 9600XT video card with a rather noisy fan. What strength resistor would I need to attach inline to lower the fan speed? I can't find any information on the wattage or amp-draw of the fan, which I realise is an impedance (Hah! I make joke!) to figuring this out, but if you could give me a general ohm range, I would be most appreciative.
It's impossible to say without knowing the fan voltage and power; there's too broad a possible range of resistor values. There's a better solution to this, but I'll ramble on about the worse one first.
If you want to drop the fan to, say, half power, then you want about 0.7 times the present input voltage, because current will fall with voltage, and voltage times current equals power, and the fan motor will work more or less like a resistive load for these purposes. Half power means one-on-the-square-root-of-two voltage, which gives one-on-root-two current; one-on-root-two squared is 0.5.
This means that if you use an in-line resistor for half power, it needs to bring the overall circuit resistance up to root-two times what it was before. Find the effective resistance of the fan motor, multiply it by root-two, subtract the effective resistance (which you've already got) from the result (which is the total you want) and you get the resistor value (which you need to add).
Let's look at two extreme cases for an unknown small computer fan. One extreme case is that the fan is relatively high power (let's say two watts, which is a lot for a regular slimline video card fan), and running from only five volts.
In this case, we've got a relatively high 400 milliamps flowing (watts equals amps times volts; two watts divided by five volts gives 0.4 amps), and the fan's acting as if it's got a resistance of 12.5 ohms (V=IR, five volts equals 0.4 amps times 12.5 ohms). You'd want a resistor with a value somewhere around 5.2 ohms; 5.1 ohms is a standard value, so that'd do.
Now let's consider another extreme case, where the fan turns out to be running from 12 volts, but only drawing half a watt. Figured out the same way, this gives only 42mA flowing, and a fan motor that acts as if its resistance is 288 ohms. Now you want a resistor around 119 ohms; 120 ohms is a standard value, which would suit you nicely.
As you can see, there's no one-size-fits-all solution. Just fiddling around with a bunch of one watt resistors from about five ohms up would give you an answer, or you could use a potentiometer; turn it until you get the speed you want, then measure its value and substitute in a fixed resistor to match - or just stick with the pot!
Or (here's the easier answer) you could use a diode or three. Plain old silicon diodes have the property that regardless of the current they're passing (in the forward direction), they drop about 0.7 volts across them (apply less than 0.7 volts across them and no current flows). In the reverse direction, "Zener" diodes also drop a set voltage depending on their type and temperature, but it's probably too high to be of interest to us here. A few cheap one watt diodes (plain or Zener, doesn't matter), set up so current flows through them in the forward direction to the fan motor, will let you reduce the supply voltage the fan sees in 0.7 volt steps, which should be fine enough for the speed control you want. Just add diodes until you get the speed you're looking for.
Since you seem to have a few felines around, I wonder if you have gotten your hands on a Litter-Robot?
No, and I don't think I'm likely to, since it'd no doubt cost a fortune to send one to me here in Australia (they don't sell outside the USA), and they're clearly not very interested in reviews. Otherwise more would exist than the two skimpy ones listed on their News page; I haven't been able to find any others on the Web.
So the Litter-Robot may well be a great automatic litter box (as opposed to some), but I doubt I'll be checking it out any time soon.
What do you think of the Fuel Atomizer 2000?
Quote: "A product that has been on the market since 1991, and since then people have responded to the Fuel Atomizer 2000 in all 50 states and Canada, plus South Africa, France, New Zealand, Taiwan, Italy, Singapore, Norway, Australia, Israel, Germany, and many more."
Note that he's claiming that Aussies buy this thing!
I find it plausible enough that Magic Gas Saver Gadget #12736 has sold OK in Australia. Australians aren't markedly less gullible than residents of various other countries.
Look at the Fuel Atomizer 2000 site and, what a surprise, you find no independent tests. Well, not counting the usual testimonials, and the known-to-practically-nobody "Carburetor Research Center", which based on one Google hit I think just makes other fraudulent fuel economy increasing gadgets.
But they do have a guy in a cowboy hat, which I suppose counts for something.
When devices like this claim huge mileage improvements just by eliminating unburned fuel, you can prove that they don't work mathematically.
If some 10mpg gas-guzzler manages 20mpg with the magic gadget, which does nothing but improve fuel combustion and thus allow less fuel to be squirted into the chamber for (at least) the same power, that means the car must previously have been spitting out at least a tenth of a gallon of unburned fuel for every mile it covered. Or burning it in the muffler and looking like the Batmobile. One or the other.
The density of gasoline is about 0.75 grams per cubic centimetre, 0.1 gallons is 379cc, so the above situation means about 284 grams of unburned fuel spat out of the tailpipe, per mile.
This is ridiculously high. Even the 1970 Clean Air Act required new vehicles in 1975 to emit not more than 0.41 grams of total hydrocarbons per mile. It wasn't until the 1980s that this actually happened, but you get the idea. Ain't nobody driving a road vehicle that exceeds that old limit by a factor of almost 700.
Here's a neat page on the subject of these sorts of gadgets.
We have some very unique and successful products that we are marketing online, including PC PowerScan. Can you please have some one contact me via email or phone in regards to how you may be able to help us promote our sites?
Please give our product a personal try - you can get a free download to check your PC for errors at www.PCPowerScan.com.
I wasn't very interested in this offer, but I tried PC PowerScan (no relation to the Powerscan "foistware") out anyway.
Well, that's a few minutes of my life I'll never get back.
The program may well work just fine, but all it'll do for free is find things wrong with a PC; if you want to fix anything, you have to pay a one-year "rentware" fee of $US67 (including a $US30 rebate if you agree to tell three other people about the product).
I kind of admire the shameless chutzpah of the business model used by Intrigue Learning (the makers of PC PowerScan), though. They'd be audacious to charge only $10 a year, but it takes real balls to charge as much for a one year rental as Symantec charge for the retail boxed version of Norton Systemworks.
I was also impressed by the brain-hurting reference to "harmful destruction" on the newbie-impressing PC PowerScan home page.
How many other kinds of destruction are there?
The above paraphrases my reply to Keith, who in turn replied to say that, "in business - profit is not a bad word". I contend that "rip-off" is, though. Unless it's two words. Discuss.
PC PowerScan's ungrammatical giant-Web-page promotion strategy does seem to be working for them, just as it's working for the spyware industry. I suppose I should take comfort in the fact that at least PC PowerScan seems to pretty much do what it says it does.
The major problem with PC PowerScan is that it doesn't seem to do much, if anything, that you can't do with free tools, or indeed with Norton Systemworks, which costs the same for a lifetime license, and has more features.
I'll be happy to take the above back if Intrigue Learning can point me to any real computer publication that's favourably reviewed their product, but I don't think any have.
Keith stopped replying to me at this point, possibly because I noticed this. Classy.
Of course, I'm sure that the people spamvertising PC PowerScan were just wildcat "affiliates", as is usual for outfits like this. That's a business technique that's been employed in the world of atoms, too.
I bet Intrigue Learning were so upset about that spamming that they carefully identified any customers who bought the product from spam and refunded their money, instead of just not paying the affiliates and thus increasing their profits, which is what all the other spam-by-proxy companies do.
So good for them, I say. Well done!
I've been noticing how broad the range of subjects of your replies (and letters) can often be. In keeping with this spirit, I'd like to ask your opinion on the following:
Is Eli's Cheesecake a valuable product?
Could you tell me whether this other delivered cheesecake would be better than a store-bought version of the same?
OK, I'm answering this one, but that doesn't mean I'm eager to receive millions of e-mails about otters, lingerie, upholstery and nose flutes. Let's keep it gadgetty, people.
Regarding the relative value of these products - they combine two things I don't quite understand.
The first thing: Premium perishable foodstuffs delivered by mail. I think this is largely an American phenomenon (Omaha Steaks, etc).
Seriously, folks; $US49 plus $US14 delivery for one cheesecake?!
I think people should be free to spend their money as they please, but when you can probably walk up the street to a cake shop and get three or four rather nice cakes with similar specifications for the same money (or, if you want to send someone a gift, call a cake shop near them and arrange it for a similarly reduced fee...), this sort of conspicuous consumption just starts looking dumb.
Six-star-hotel-room-service pricing is perfectly normal in the mail-order-perishables market, of course. I don't know what steak costs where you live, but where I am you're talking $AU30 ($US22) per kilo, or thereabouts, for something pretty nice. Prices have been pushed up a lot by the drought Australia's been suffering for some time now.
Unless there are some bargains lurking on the Omaha Steaks site that I haven't found, they will relieve you of at least $US60 per kilo for cow-flesh.
At that price, their steaks had better lower your cholesterol.
Maybe the second cheesecake you linked to is better value, pound for pound, than the Eli's version; I don't know. I think they're both a pretty goofy thing to buy.
This brings me to the second thing I don't understand, which is cheesecake. Sorry, but I've never figured out why people think it's such a good idea to take cheese and put it in cake. Even if you like cheesecake, though, I doubt paying five times as much will give you even twice as much cake-munching joy.