"BIG UFO" UV LED Keychain Lights, retail $4 (http://ledlight.freeshell.org)
Manufactured by (unknown) (see below for distributor info)
Last updated 11-21-07
The "Big UFO" style number 2 is a fat, keychain sized violet LED flashlight. The decidedly *cool* looking unit is equipped with a standard high-powered violet (near-UV) LED emitting at just under
400nm, and is powered by a pair of CR2016 lithium coin cells.
The sample being tested on this page is the silver/chrome model on the right in the above photograph.
The Big UFO is ready to use right out of the package. Press the grey button down to light it up, quit pressing to turn it off.
The light comes with a unique spring-loaded clip and a 360° swivel hook. This is affixed to a smaller ring on the back of the light, making it possible to change
batteries without having to remove it from your keychain.
To change the batteries, follow these steps.
1: Unscrew & remove the three screws holding the case together.
2: Flip the light upside down, so the button is facing the table.
3: Remove the bottom half of the case, try to not drop the chrome "U" shaped thingie.
4: Lift the entire black assembly (including LED) straight off its posts.
5: Carefully remove the batteries, being certain the metal switch dome doesn't fall off.
6: Replace batteries, flat side (+) facing you. The negative (-) side should face the dome switch.
7: Replace entire black assembly back onto its posts, replace the lower half of the flashlight & chrome "U", and screw in the screws.
Take care not to overtighten the screws, as it is possible to strip the screw holes. The screws are very slightly countersunk; so stop screwing as soon as they're just below being flush with the flashlight body.
They should turn easily until you reach the end; even with a narrow handled eyeglasses screwdriver. Once they stop turning easily, that should be it. Don't force them or you're almost
sure to break off or strip out the screw posts.
The "Big UFO" style 2 (narrow angle) is made of grey plastic and thick chrome plated wire, and like its fraternal twin brother, is not durable enough to withstand being run over or stomped on.
However, given a modicum of care, it should happily provide you with years of service. It too survived being dropped onto no pile/no backing carpet and on bare flooring.
It is not waterproof, so you should try not to toss it into a river, flush it down a wall urinator, or let it go through the dishwasher. Like most small personal electronics articles though, it will survive a quick
rain shower without any problems.
The LED in this unit appears to use a Cree MegaBright UV chip, and appears to be emitting its peak between 396 and 398nm, which is well within the "useful" range of these new LEDs.
I define the "useful" range as being anything shorter than 400nm. The beam is typical for this type of LED, and appears to be in the 15-20° range. This is fine for money checking
and looking for other fluorescence, and may have a slightly longer overall range than its wide-angle brother.
Beam photo. Photometric tests/measurements are not
possible due to short wavelength.
The money shot.
Spectrographic analysis of the LED in this flashlight.
That hump near 770nm in the very deep red region of the spectrum is the
second order reflection from the spectrometer grating, and may be disregarded.
Light is being tested alongside a wide-angle "Big UFO" that arrived with it.
They arrived here on approximately 04-05-02.
While changing the batteries to perform spectroscopy, I was unable to reassemble the unit in working order.
Not as durable as some others
Tools required for battery change
PRODUCT TYPE: UV/near-UV 'money detector'
LAMP TYPE: LED
No. OF LAMPS: 1
BEAM TYPE: Medium angle with several faint rings
SWITCH TYPE: Dome type momentary pushbutton
BATTERY: 2 ea. CR2016 lithium
CURRENT CONSUMPTION: Not known
WATER RESISTANT: Light weather resistance only
ACCESSORIES: Split ring, batteries
WARRANTY: Not stated
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