LEP white light source -edit- LEP handheld flashlight build and test photos

[djQUAN]

I wanted a LEP flashlight but it's too pricey and not available in my usual purchasing sites so I couldn't get one.

I was suggested to check out an Ali store for an engraver head diode upgrade and stumbled upon this gem.

65.0US $ 50% OFF|Laser Tree White Laser Modlue, Laser Phosphpr Module, Reflective Mode, 400ml,500lm, Laser Flashlight, Laser Headlight Wood Tools - Woodworking Machinery Parts - AliExpress

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It looks like an LEP light source so I purchased one along with my diode and it arrived.

Spec sheet from the ad


It is not small so making a handheld might be a bit bulky but I might find a way.


Aperture side, power off


Aperture side, low current


With about 1A current to the diode, (can do 2.5A max)


Using a random lens from DTR's projector optics package


I have a few ideas to make this work in a handheld so I'll update this thread as it progresses. RHD's sample driver might finally be used here.

 

[djQUAN]

V1 build - proof of concept

I used my laser engraver to transfer the cad drawing to aluminum plate for the lens and LEP holders to be able to test its performace.


Here is the etched aluminum plate which was sprayed in black paint.


LEP light source and a lens from DTR's projector lens assembly.


I added a heatsink at the back of the LEP source as it gets pretty hot in use, about 11W power input.


Test glowing


Springs are added on the ends of the standoffs so that I can fine tune focus


The semi-portable assembly so I can take it to test at longer distances. I used rhd's clean edge driver which pushes about 2.7A into the LEP module with 2x 18650 in series.


Testing at a longer distance in the garage


Obligatory beam photo


The limitations of a small diameter lens with a bit long FL (for this purpose) is showing. It is rated at 420lm output but a lot of it is wasted as the light is outside the lens diameter. Only about 40% of the emitted light is focused into a tight beam. A bigger lens is needed.

 

[djQUAN]

V2 - Bigger lens = better output

I have an old OEM projector headlight with the reflector bowl corroded but the lens is still good. I tested the lens by temporarily gluing it to the LEP module for testing.


It does look promising and nearly all the light output from the LEP module is within the lens diameter. The spot size is also decent.


Now to make it a little more permanent. The aluminum plate will hold the LEP module and the round one is from a lens holder assembly from a 100W LED flood lamp. The lens used is crap but the car headlight lens fits perfectly so I get to reuse the holder assy.


After a bit of manual machining, they line up perfectly.


The LEP module installed, the mechanical assembly uses brass standoffs to space them at the correct distance.


Ready for testing. Driver is wrapped in heatshrink tube for insulation, during testing, heat is not an issue for the driver as it is over 90% efficient at most operating ranges.


Lit up. Notice there is much less back spill compared to V1. The only back spill is from due to the lens not having anti reflective coating.


Distance spot test.


to be continued...

 

[djQUAN]

V2 pt2

The joys of having a laser cutter/engraver. I made cardboard spacers to fine tune the lens focus distance from the LEP module.


A fan was added with a smaller heatsink to improve the operating duty cycle.


The red and black 2mm jacks are for the thermistor sensor output built into the LEP module. A multimeter in ohms mode can be plugged here to estimate diode temperature during prolonged runtime.


Beamshot with the new lens


A distance test: Control image


With the LEP on.The tiny spot at the end is a water tank about 600m away from my house. I had tried a structure 1km away but it is too well lit to be able to take decent pics but It does reach. The flashlight should be able to throw further in darker areas.


Nearly completed. Just needs a better way of holding the batteries. I decided on 2S2P with BMS for longer runtimes. Handle was carved from two 12mm sheets of some material used for tabletops, a synthetic resin substitute for granite/marble. It was easy to cut and shape but smells like fiberglass resin.


Just below the lens, above the trigger button are two 5mm LEDs which are used as dim lighting (separately switched) when walking at night as the main beam will be too blindingly bright up close not to mention the small spot is pretty useless.


Back side with the fan visible. The fan is a 5V unit overdriven at 8.4V but works just fine and pushes a lot more air for a 25mm unit.


Just for completeness, the other side.


It just needs a better enclosed battery holder (acrylic box comes into mind) and this should be complete.

 

[steve001]

Check "Surplus Shed" for large diameter lenses.

 

[djQUAN]

Check "Surplus Shed" for large diameter lenses.

The OEM projector lens works quite well actually so I guess I'll be keeping that. I was looking at these before as a source of lenses but thought I'd try the ones I had on hand before spending which turned out great.

I had finished the battery box using acrylic.


An XT30 was used to make the holder detachable.


4X 18650 in 2S2P with BMS to prevent over discharging in extended use.