Anyone seen a schematic for those little clip on flashlight that simply clips on a 9V battery? I can certainly build the board, etc but wondered what other's have done. I want to add and little on/off switch, etc.
Why? There are a zillion different torches out there that cost next to nothing and are more rugged, and run on cheaper and higher energy density AA or AA cells. A 9V battery has poor energy density, so is a very poor choice as a battery for a flashlight. You'd at least need a DC-DC converter to get the most efficiency.
Dave :)
There's a certain irony here. Those "flashlights", at least the ones I've seen, are basically LEDs attached to a connector for a
9v battery. The intent being that you can dig up a 9v battery and have a flashlight, but no sense wasting space until you actually power it up, which is the case with AA cells, that would require something to hold them. WHen I've seen them in the flyers, I imagine them as a supplemental thing, something to have around for emergencies rather than using as a flashlight on a regular basis. 9v batteries are easier to get (and cheaper) than button cells that are often used in cheap and low cost LED flashlights.The irony is that the connector on those 9v batteries works as a pretty good switch. They are (usually) solid when connected up, yet not difficult to detach when you want to turn off the light.
I've not actually tried one, but they appear to be pretty good for what they are supposed to be. But once you start fiddling, then their appeal goes out the window.
If one actually needs a switch, one might as well buy a white LED, a resistor and a switch, and wire them (with a connector or just solder it all together) to 9v batteries. You get the use of the 9v battery, the actual end results wanted, and likely it is cheaper than the "flashlight" that may not be anything more than a dropping resistor and the connector.
Or one can get fancy, get a battery holder (some even have connectors that are a match to those on 9v batteries, and use AA cells to get the same effect.
Oddly, I plan to buy an LED flashlight this week, having seen them at the drugstore for $2.49 and they have 5 LEDs. I won't lose much if they aren't any good, yet if they are, I have some uses for non-portable light, and I'll just scrap the body of the flashlight and use the LEDs.
Michael
Sure, but AAA or AA's are even easier and cheaper again. You can get torches on eBay for next to nothing, and they take a single AAA or AA battery. Also, they usually work with a "flat" battery too, the one I have works down to 0.7V cutout.
In my experience a AA or AAA battery is MUCH easier to get than a 9V battery in an emergency, espcially if you are out in the field somewhere. For instance, if I've gone bush then in my pack I might have a GPS, camera, UHF radio, or PDA, all of which use AA or AAA batteries. At home I have a draw full of AA's and AAA's but never seem to have a
9V battery around when the smoke alarm starts beeping.Yes, they work well for that. But the problem with 9V batteries is that they can short out easily, you can't just throw them in your pack or glovebox and necessarily expect them to be ready to use in 12months time.
Or just buy a real AA or AAA torch for a few bucks and be done with it. The single cell ones are tiny, my wife has a single cell AA 12 LED aluminium light in her tiny purse.
If you want a really tiny top quality AAA light, look at this one: http://216.71.117.133/arc-aaa.shtml
Dave :)
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