Aqualab

Celebrating the independent kiwi spirit of invention.

Fabrication: 17-mode Triple Cree XP-G R5 Caving Headlamp

By Ian Mander October & November 2010.

Various notes not used elsewhere.

Modes

**Triple XP-G Possible Modes**
Mode	Lumens	Current	Duration
Low	3 x 3.3 = 10 reading	30 mA	2.75 days
Medium	3 x 25.8 = 77.4 general caving	180 mA	11 hours
High option 1	3 x 48 = 144 demanding caving	330 mA	6 hours
High option 2	3 x 60 = 180 demanding caving	410 mA	4.8 hours
Turbo	3 x 350 = 1050 photography large chambers	3 A	35 minutes

FWIW that turbo mode would be about as much light as a 45 W halogen bulb produces (ie, almost a car headlight). Heat sinking required!

There's not much efficiency gain at low currents, so there's not actually much difference in current required to produce 75 lumens between one and four XP-Gs (for example), but the total output of over a thousand lumens from three XP-Gs at 1 amp each would be "satisfying" and different optics could be used on the separate LEDs. I suspect 4xAA Eneloops would be required to provide enough voltage for the drivers to stay in regulation at high currents using AMC7135 linear regulators. (Yes, since confirmed.)

To drive an XP-G (or an array of them) at 180 mA (total) I'll need a new driver. The AMC7135 used in my present headlamp works very nicely with 3xAA cells, but the output of each one is fixed at 330 mA. So I want a constant current driver which can be set to 180 mA output and will run on 3xAA or 4xAA, or even 3xAAA.

Completed headlamp

This headlamp became a bit of a legend, if I say so myself. See the PDF write-up posted here: https://www.hometutoring.co.nz/electronics/downloads/Cave Tech, AHE Science Fair Aug 2011.pdf

Celebrating the independent kiwi spirit of invention.

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Please don't buy stuff from a country in the middle of intimidating its neighbours.