UK 4AA eLED FYI...

This module will also fit and function in the 2AA version of the light. (UK 2AA)

I have no idea why UK does not advertise this.
I am currently running mine with the alkaline cells that came with the light; but when those eventually die,
I plan to insert lithium batteries for the light weight and cold temperature performance.

Comments?

Comparable brightness?

I'm gonna guess - yes. I've only had the two lights since last night, and I have NO objective light measuring equipment.
(Kinda difficult to make a usefull eyeball comparison if I hafta swap the module between two bodies. /ubbthreads/images/graemlins/wink.gif

Hopefully someone with equipment will pick up on this.

I have the module in a UK 2L; which makes for a small light package; it's one of the flashlights Ikeep in my car.

I can't imagine why UK doesn't advertize, or sell the module in the 2AA version; I've had a UK 4AA model for many years, but it is a bit bulky; the 2AA with the eLED module would certainly appeal to a lot of people.

Is there any difference in brightness between the 4aa and 2aa versions (assuming they're using the same eLed module)?

A quick and dirty comparison with my 4AA eLED module:
Using a G.E. Lux meter, the output dropped from 240 units on 4 AA alkaline cells to 175 units running on just 2 AA alkalines.

The UKE placed next to an am radio (in between stations), sounded from the speaker just like what a Bell Jet Ranger 209 helicopter makes in the process of taking off. It's converter whistles up and down like crazy /ubbthreads/images/graemlins/wink.gif /ubbthreads/images/graemlins/icon15.gif /ubbthreads/images/graemlins/grin.gif

stainless or TRC: do you have a digicam with manual shutter option? Fix the shutter opening to a certain value and take a beamshot on a whitewall.
swap the eled module to the other body and take another shot with the same shutter value.

then we can objectively compare the brightness of 2aa and 4aa /ubbthreads/images/graemlins/grin.gif

[ QUOTE ]
vcal said:
he UKE placed next to an am radio (in between stations), sounded from the speaker just like what a Bell Jet Ranger 209 helicopter makes in the process of taking off.

[/ QUOTE ]

vcal,
I've been in quite a few Jet Rangers (& Long Rangers) and they were all some variant of a 206 model. What's a 209?

Make that a 206 then...-it's been something like 20 years since I've flown in one. /ubbthreads/images/graemlins/icon15.gif

What would be interesting is for someone to hook up the UK eled module (4AA version) to a power supply and starting at 6v crank it down to see where it drops off, IE how low of a voltage input is needed to operate the light. It could be that when it reaches around 3v the light is getting close to shutting down. If the module wont run well at about 2.2v then using it on a 2AA body probably won't give you reasonable runtime.

[ QUOTE ]
Ny0ng1 said:
stainless or TRC: do you have a digicam with manual shutter option? Fix the shutter opening to a certain value and take a beamshot on a whitewall.
swap the eled module to the other body and take another shot with the same shutter value.

then we can objectively compare the brightness of 2aa and 4aa /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

Sorry - if my camera has a manual mode, I don't know how to access it. /ubbthreads/images/graemlins/blush.gif


vcal:
Can you repeat the test using two LITHIUM batteries.
I suspect the modual will run brighter, and much LONGER due to the flatter discharge curve of the lithium batteries.

Where is "Runtime Roy" when we need him? /ubbthreads/images/graemlins/grin.gif
(Maybe I should pm him.)

Also try NiMHs.

>stainless/scudinc
Two more FYIs:
Two L91 AA Lithiums applied in series produced almost the same output as 4 AA alkalines. (240 units-like last test).

Applying two 1.2V NiMH (2.47V measured) in same series resulted in a dramatic loss of output...-down from the 2-AA alkaline output of 175 units down to just 40 units.

So is there a buck, boost or buck/boost circuit in the module?
If it does boost some then maybe someone can change a part or two and make it work right with normal alkaline/nimh in a 2AA host.

[ QUOTE ]
vcal said:
>stainless/scudinc

....Two L91 AA Lithiums applied in series produced almost the same output as 4 AA alkalines. (240 units-like last test)....



[/ QUOTE ]

Yahoo!! Maybe I won't wait until the alkalines die before putting in the Lithiums. /ubbthreads/images/graemlins/grin.gif

vcal: THANKS for doing that test. /ubbthreads/images/graemlins/thumbsup.gif

Another thing you could try is 2 3v AA lithiums. That would probably give you more runtime before voltage dropout.

Anyone with a eLED wants to try out 3x123s or 6xAAs? /ubbthreads/images/graemlins/grin.gif

[ QUOTE ]
Lynx_Arc said:
So is there a buck, boost or buck/boost circuit in the module?

[/ QUOTE ]

My guess: it's a buck that goes to constant 'ON' (effectively 'direct drive') when the input voltage is close to or lower than the LED forward voltage.

Best,
Jamaica

Yea after I said that I realized it was probably a buck circuit doing that. It would be nice to put a boost circuit version for a 2 cell UK2AA light though. I had an incan 2AA and gave it to my sister to use, it is a nice light.