LED flashlights (LED beam angle)

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ash_dac

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Joined 2005
#1
Hi,

I received a 'free' blue LED touch with batteries (2X1.5V) from my parts supplier with the last order. The torch has a LED socket so allows interchanging of LED's.

Can I replace this LED with an ultrabright white ?

What is the beam angle I need for a torch ? (it's currently blue

Plastic LED's - has anyone tried heating the LED plastic to manipulate the beam angle ?
 
#2
I think you can replace the led. You need to make sure the current doesn't exceed the leds requirements or it may get toast. This needs a resistor in series. Try different values (or a variable one). Start with higher values. There is a chance the torch already has a resistor. But most leds I see on e-Bay have voltages between 3V and 3.8V, which 2 AA batteries won't be good for. Some I see have around 2V though.

http://cgi.ebay.ca/ws/eBayISAPI.dll...ssPageName=MERC_VI_RSCC_Pr4_PcY_BIN_Stores_IT

I guess you can flatten, or even cut the round tip (lens) if you want a wider beam. That must be treated as an optical surface though, otherwise you may get distorted shapes or diffuse light easily. I think a lower angle value (<60degrees) is better for a torch, otherwise the light intensity will be too weak.
 
#4
a white LED is basically a blue LED with the die inside a flourescent material to "fill" the missing colors to get white light but electrically speaking, it's a blue LED.

I assume that the flashlight has a small boost powersupply to run the LED with only 2 AA cells. but since it's already using a blue LED, using a white LED wouldn't be a problem.
 
#6
It depends. If you would use a current source a parallel resistor would do, but 2AA batteries come closer to a constant voltage source.

Not all white leds use phosphor to glow white. Some use separate RGB junctions, the so called 4chip ones. They are even brighter.
 
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