I’m a Mechanical Engineering student at Virginia Tech. I’d like some help getting started with a project. I have never built a flashlight before and I haven’t had much luck finding resources that answer my questions.
I’m building a headlamp that has two independently controlled xhp70 emitters, one flood and one spot. It will be powered by two or four 18650 cells. I’d like to have infinitely variable control of each led, similar to the Nitecore HC90.
- Are there drivers available that can fulfill these requirements?
- Has something similar been documented?
- Are there any good build threads or articles I should be aware of? I’ve tried looking on a variety of forums.
I’m not concerned with output over 1500 lumens. More is neat obviously but I chose the xhp70 assuming it could offer longer runtimes on the lower levels.
Saw your thread yesterday; I ducked it a bit hoping to see if some sort of expert would chime in and see his/her suggestions. No luck it seems, yet.
0K. Please bear in mind what you are proposing may be somehow still unheard of, maybe and mostly because of the infinitely variable control “eccentricity”.
If you are willing to use dedicated flood & throw emitters, in my limited experience this is what I can suggest:
For flood, I'd fit a plano-convex lens just above the emitter. This guarantees a very pleasing, uniform cone of light.
For throw, maybe some sort of narrow angle TIR (Total Internal Reflection) lens; this should also provide a uniform beam of light.
With regards to drivers, all I can say is that you may need to come up with some sort of custom driver design. If you are willing to use batteries in series, there is at least a handful of good DC-DC constant current buck drivers… with fixed modes. However, attaching a logarithmic taper potentiometer in series with the current sensing resistor(s) may result in a relatively simple and effective solution to the problem. I am no electrical engineer, though, maybe you can come up with a better solution.
Enough for now, let's see if someone chimes in with food for thought.
Hi, and welcome to the BLF!
I am curious, I don’t have an answer, but a question. Are you building a bicycle headlight or a headlamp for a person’s forehead?
i’m certainly not an expert but am currently building a twin led lamp and have thought over very similar idea’s
for control you’ll probably be better off with 2 drivers, one per led each with a separate switch. one of the custom drivers with ramping should be what you are after.
battery wise id go with a 2s2p setup that should give you enough head on the voltage ( assuming 6v led) run time could be limited though.
2 amps gives 1500 lumens i think, so you’ll need 12VA per led for an hour totals 24VA for one hours run time.
good panasonics are now up to 3400mAh at 3.7 V so a 2s2p set up would give 7.4V @ 6.800Ah or 50.32VAH
50.32/24=2.097 hours run time - this is with 100% efficiency, so after taking into account loses id guess at somewhere between 1.5-2 hours with both leds on 100%
with regards to optics, im not sure youll get much of a spot with such a large emitter in a small housing, an XML is difficult enough to get a real tight beam, although may there are some magic TIR’s out now? or possibly a fresnel
Thank you all for the responses! I’ve done some research over the week and I have some answers and new questions.
Burkuti, I’m planning on using two emitters. The xhp70 (or xhp50) for flood, and likely an xp-l or xhp35 for throw. I may have to drop the infinitely variable idea, but I’ll keep looking.
Paul321, this is going to be mounted on a Petzl Vertex helmet for use while caving.
Bertie_Bassett, those are impressive numbers! I’m liking where this is headed. I will likely make a 2s0p battery box and carry spare batteries to keep some weight off my head. I’m hoping to use the xhp70 only as a flood, with another emitter for a spot. I’ll look for those drivers.
I am leaning towards the taskled dualflex, largely because of its wonderful UI, but it only puts out 3.5A. Does anyone know if it can drive both leds at 3.5A, or just one at a time? Does anyone know of any drivers that push 5 or more amps with similar UI’s?
