Low voltage white LED

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**DONOTDELETE**

Guest
I recently bought a 1-led white bicyclelight made by Smart Smart bikelights. The thing is that this light only uses 2 alkaline batteries. I did some testing on the led with different voltages and at ~2.70V it was drawing ~30mA and at ~2.30V it was 7-8mA. At 30mA it was about as bright as a Mag Solitaire. Does anyone know where to get a LED like this?
I already emailed the manufacturer of the ligt but didn't get any reply.
 

Steelwolf

Flashlight Enthusiast
Joined
Feb 6, 2001
Messages
1,208
Location
Perth, Western Australia
Hi Bjoern, Welcome to the forums. I'm sorry no one has addressed your question sooner. This is kind of odd as there are quite a few knowledgeable people here.

Personally, I have tried looking through the website that you linked to, but there aren't alot of descriptions for the light that you mention. In fact, I'm not even sure that I've found it. Could you supply a model number, or the precise link to the product?

You mentioned that you tested the LED. You mean to say you tested directly across the terminals of the LED, or did you test across the battery output terminals? Are you able to supply photos of the lamp and the LED?

Barring any further information, there is not much I can tell you. All I know is that a proper white LED requires about 3.6V before it will light up, though the current it draws can be less than the stated 30mA. To overcome this limitation, companies have come up with various DC-DC convertion circuits, some more efficient than others. Some companies who have done this are: Arc Flashlight, CMG Equipment, Brinkmann LED light and the Princeton Tec Matrix. (There are quite a few others, but I think that is enough for now.
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Another way to drive the LED is to use the 555 timer IC and a bunch of capacitors which charge and discharge, but this produces a flashing light rather than a continuous beam.

Hope some better answer is forthcoming.
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I certainly would like to find out more about low voltage white LEDs.
 

The_LED_Museum

*Retired*
Joined
Aug 12, 2000
Messages
19,414
Location
Federal Way WA. USA
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Steelwolf:
Hi Bjoern, Welcome to the forums. I'm sorry no one has addressed your question sooner. This is kind of odd as there are quite a few knowledgeable people here.<HR></BLOCKQUOTE>

Apparently I missed this topic completely... I must have gone out and gotten hammered that night or something.
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Anyway, I don't know of *any* white LED that can operate correctly much below 3.4 to 3.6 volts. They'll occasionally glow dimly at 3.0 volts, but so dim as to be pretty much unusable for anything but a toilet finder or a nightlight.

This light you're talking about must have some kind of additional circuitry somewhere inside it besides the LED. It could be just an epoxy blob tucked away somewhere, or there could be a discrete board with several small components on it.
 
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