My experience with LED lights has been limited to the Photon and other microlights, which i have found to be only marginally useful. They're ok for finding the keyhole in the front door when the light's out, but for seeing something across the room or for reading something, they're not too useful. That's why I've taken to carrying a UK 2AA on my keychain.
I bought the EternaLight on a lark because it looks like a cool toy, but it's turned out to be a very useful light as well.
As I mentioned earlier, it's the size of a pager, with four bright white LEDs in a row on the front and three surface-mounted buttons on top, labeled On/Off, Mode, and Rate. The regular models take three AAs. The basic (cheapest) one is a square box. The "Ergo" model (which I have) is more rounded and easier to hold, and has a lanyard hole. The marine model is the same as the Ergo, except yellow instead of black, and it uses lighter lithium batteries, so it floats. I assume they're talking about the lithium disk batteries, not 123As.
The best prices I found were at <a href="http://www.tannersstorefront.com/eternalight.htm">Tanners</a>, $37.20 for the basic version, $48 for the ergo, and $62.40 for the marine.
The light consists of two halves held together by four screws, with a rubber gasket in between that supposedly ensures watertightness to 25 meters. When you open the unit, you can see that the screws hold the two halves together with some pressure. The top has a layer of foam inside with a mildly sticky substance on it, which presses down on the batteries to hold them in place. This is good, because the battery contacts are what seem to be relatively flimsy springs. They would not hold the batteries in place by themselves, but the foam and the adhesive seem very secure. You just have to be a little careful while opening it up to change the batteries. There's also a tiny circuit board inside with a processor chip to control the unit's functions.
Turning on the EternaLight lights all four LEDs at full intensity, after a little sequence in which each one blinks in turn.
Like most LEDs, these are probably better at being seen than at casting light for you to see. The company's advertising says that the light is visible at up to three miles, and I believe it (on a clear night, anyway). If you stare directly into the LEDs at full intensity, it's painful, but not nearly as much so as my 120 lumen SureFire 6P. With the room lights on, it doesn't seem very bright, but in darkness, the unit casts a very useful light with a moderately focused bright spot and a diffuse light around it that gives you a good sense of your surroundings. I've been wearing it on a cord around my neck and I've found that turning it on and letting it dangle (pointing downwards) provides sufficient ambient light to walk around the house in total darkness while my hands are full with something.
When you turn the unit on, it's in Timer mode (one of seven). At 2 1/2 minute intervals, one of the four LEDs shuts off until, after ten minutes, the unit is shut completely off.
Clicking the Mode button cycles you through the seven modes. The second is On/Dim, which starts out at full intensity and will remain on indefinitely. As you repeatedly click the Rate button, all four LEDs dim in small increments. The light still remains useful in several of the dimmer settings, and battery life is extended enormously. They advertise up to 700 hours on one set of batteries at the lower settings, although I haven't tested this.
The Flasher mode blinks all four LEDs at full intensity about once every second. Holding down the Rate key slows down the flash rate until it reaches its minimum, then cycles back to the fastest. This is great for signaling from afar and triggering epileptic seizures in strangers on the street.
The Strobe mode blinks each LED in succession at a much faster rate, which you can adjust with the Rate button to "freeze" the motion of an electric fan or produce a stop motion effect. Practical uses? I can't think of any. Maybe if I was into disco...
Dazzle mode blinks one LED at a time left to right, then right to left, then the two outer ones, then the two inner ones, then all four, in rapid succession. The Rate button does nothing in this mode. It's a cool effect that would be very noticeable from a long distance away.
SOS mode repeatedly blinks all four lights at full intensity in the standard SOS morse code signal. Here again, the Rate button has no effect.
Pulse mode blinks all four LEDs in the same way, but only when you push the Rate button, so that you could send your own Morse code messages, if you were so inclined.
Ok, so it's a new toy, and I find myself turning the lights off frequently in order to play with it. It would be great for kids to use to play Star Trek games, as it looks very much like a hand phaser. But, as I said earlier, it's also a very good general use light to have with you. For reading a map or changing a tire in the dark, for example, I'd rather have an EternaLight than a SureFire assault light. It's flat enough to carry in a side or back pocket unobtrusively, as barrel-shaped lights often are not.
Ok, so this is probably a lot more than you wanted to know about this, but I'm procrastinating when I should be working, and I really have no one else to tell this stuff to who doesn't think I'm nuts for spending lots of money on flashlights.
[This message has been edited by craigz (edited 07-21-2000).]
