Building a Can Light

[Pinkank]

Hi,

I am brand new to this light building stuff. I have been browsing these forums for the last couple of weeks, reading up on many of the projects that have been listed here. I've also bought and read Steve Lindblom's Divelight Companion (which I actually did not find as helpful as I had hoped as it doesnt cover much on LEDs).

I would like to build a light with the following general specs:

LED
Lots of throw, very little flood (Im not usually in the best of visibility)
1000ish lumens (or more, i like lots of light )
2-3 hours run time
Reed switch (only on and off)
Head to be machine out of solid aluminum (I have access to a good shop)
Can to be delrin or whatever is recommended

However I dont have any experience at this and I wanted some advice. I was thinking of using an aspheric lens. I dont know if I should use a single, or multiple LEDs, and should I go with SST-90 or P7 or what? I dont know much about batteries, I was thinking mutiple 18650s in a custom cell (how many?), and do I go protected, and how choose/set up a PCB. And then how do I build a good driver?

Haha, Im sure I sound like a super noob, but any help would be greatly appreciated.

Thanks a lot.

 

[jspeybro]

The 44mm asperic lenses of dealextreme fit a Mag nicely and have been used with good results. you could use the mag dimensions as a reference.

P7 is nice to experiment with as it is cheap and a lot of cheap drivers exist.
SST-90 will need better heat management. SST-50 could be a step in between and can for example be driven by using 2 P7 drivers in parallel.
Edit: when using an aspheric, I don't think using multiple LEDs is a good idea, although I haven't tried it. multiple die emitters seem to work reasonably well although there may be some 'donut' effect depending on the alignment of the optic.

you can calculate the burntime by calculating the power that the led and driver consume and compare this with the available power of the batterypack.
in short,
battery voltage [V] times battery pack capacity [Ah] divided by (led voltage [V] times led current [A] divided by 0.80)

the 0.80 is to take into account the (in)efficiency of the driver. 80% is probably a bit on the conservative side.

be sure to use the right units (don't mix mA and A unless using the proper correction factors...)

 

[Packhorse]

An aspheric will give you them beam you are looking for. A SST-50 will give you a tighter beam than the SST-90 and still give you 1000 lumen.
Multiple XR-E's will give the tightest beam but will be harder to make.
Battery pack voltage should be matched to the driver.
I like to use 7.4v Li Ion packs since this works well with all the drivers I use and I have multiple packs I can swap between.
The amount of cells in a pack will dictate cannister size and run time.

 

[Pinkank]

Okay, Im starting to get an idea about what I want to do. The only thing I still cant find much info about are drivers.

Where do I get them? Do they come prefabricated or do people make them themselves? Does running them in parallel just have them put out twice the current?

Thanks for the help guys.

 

[jspeybro]

the driver depends on the LED you want to use.

for cree or SSC LEDs, you can easily use drivers from dealextreme.com and kaidomain.com. cheap and free shipping, but chinese and usually tend to be less reliable, although I didn't have problems with them so far.

for luminus leds (sst-50/90) you can have a look at taskled.com and http://www.pcmus.com/Dive-Photos/LED-Genie.htm
Also the user Der Wichtel on this forum sells drivers for these LEDs.
DIWdiver may have some linear regulators http://www.candlepowerforums.com/vb/showthread.php?t=264687

These higher ampere drivers tend to be more expensive.
Torchboy also created a nice overview of drivers: http://www.videofoundry.co.nz/ianman/laboratory/research/driverlist.php

good luck.
Johan