test data of LED module from headlamp

Coherence

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I have just taken apart the LED module for the Matrix headlamp by Princeton Tec.

Picture and reviews

number of led's: 3 white

I have an adjustable power supply and measured some numbers...

note that brightness is just my subjective opinion with 0.0 being darkness and 1.0 being a Photon Microlight II with new batteries.

Volts Current (mA) Brightness
------ ------------ -----------
0.0 0 0.0

(current remains 0 until)

0.8 100 0.6
1.2 90 0.8
1.5 70 0.8
1.7 60 0.8
3.0 35 0.8

(you can reduce the voltage all the way down to 0.2 and still keep the module lit (!) )

0.2 70 0.1

It appears to try and maintain a constant power of 0.1 watt based on this data.

The light is whiter and a bit more spread out than the Photon.

Anyway it is a nice module for projects. Runs fine off of a lithium 123a, or D, C, AA, etc. cell (yes, I did test them). Even a single NiCad or NiMH at 1.2V should work fine.

Some quickie calcs for battery life based on measured current drain...

AAA alkaline = 16 hours
AA alkaline = 41 hours
C alkaline = 120 hours
D alkaline = 257 hours (!)

123A lithium = 40 hours

Now I just have to think up a good project to use it in...
 

Lux Luthor

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Thanks for the data. Can you tell what kind of circuitry appears to be in that thing? I've never been impressed with its light output, but I'm wondering if it would be possible to blast it with 6 volts, say by screwing it on to a Tec-40. Also, can you tell if the LEDs can be removed? I wonder if they're using inferior ones.
 

Coherence

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I am reluctant to fully disassemble the module as I may not get it back together intact, so circuit details are hidden from me.

I did try boosting the voltage above 3.0, and it does start to overdrive the LED's.

Since I intend to use the module I didn't push it to 'failure'.

I believe you can unsolder the LED's if you desired.
 

Coherence

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Okay I took it further apart and the circuit is made of:

2 capacitors, a coil, and an 8-pin IC

(all components are surface mount)

plus the three LED's

the chip is marked

1678
EUA

Sounds like the same kind of DC-DC converter discussed in another
thread. People seem to be having trouble getting parts locally, maybe you could order just the LED module from Princeton Tec, take it apart and have a ready made constant power supply.

The circuit board is about as big around as a quarter and about 1/8" thick. Not including the LED's. Weighs next to nothing as a bonus.
 

Lux Luthor

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Thanks for the info. With the IC in there, it's hard to guess how much you could really push it. A stable power supply doesn't really indicate what will happen with batteries. Only thing you can really do is hook it up to different battery configurations, test for heat, and hope the IC doesn't burn out. Since the thing is expensive, I'd be reluctant to do that, though. In any case, it gives me something to think about.
 
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