My Surefire L4 OSRAM Ostar Mod aka "Flaming Fields"
The OSRAM Ostar 6 die emitter in its higher luminous flux bins is the emitter with the highest light output available today. So sure enough building a flashlight around this beast is more than tempting. Since i won't be lugging around a large torch on a regular basis, i rather wanted something small enough to be sort of an EDC. Lots of useable smooth light is what i had in mind and this is just what a multi-die emitter really "shines" (pun intended
) at.
Full credit for the the idea behind this mod has to go to ARCMania who has pioneered building an Ostar into the KL4. While his great work involved custom parts like a pill to house electronics and hold the LED, i am making use of the existing parts of the Surefire L4 host. The KL4 is pretty much the perfect host for this project since it will tightly fit LED and converter with no room wasted.
The Build
Lets have a look at the list of parts that went into this mod:
1) Opening the KL4 head
The first step is far from being the easiest since the treads on the head are locked with a black sealant. Some people seem to have been lucky and not needing much force to open the head. This one needed both heating and a combination of a vice and a wrench to come apart. Using strong and thick rubber sheets wrapped around the head preserves it from getting scratched in the process.
Once this is done we are removing converter and the Lux V LED, it will probably end up in my small LED museum.
2) Milling the head for the Ostar
Looking at the parts at this stage you can see that the Ostar will fit the grooves on the backside of the KL4 reflector. For a perfect fit we need to take off some material though. I am using an ordinary drill in a rig and some small milling tools. To avoid any damage and too much debris inside the reflector i have masked things off with some tape. I also need two slots since the wires to the LED are running at the top of the MCPCB. Fast forward about an hour the head looks as in the picture below.
I also enlarged the reflector opening by a few tenths so the Ostar will go in all the way.
3) Other mechanical work
The "LED support" with its two screws will be used in the mod, but it does need two new holes for the wires.
The Ostar MCPCB needs to be sanded down to be slightly smaller in diameter than the inner diameter of the head.
Some more sanding is necessary on the converter boards to mate with the LED support and the battery contact part.
4) Assembly
Blue Shark and Remora are stacked as tightly as possible. I am using isolating polyimide (aka Kapton by DuPont) tape wherever unwanted electrical contact could be possible. A cut piece of copper attached to the top of the DC-DC converter chip will make thermal contact to the aluminium LED support.
A cut piece of polyimide shields the top of the Ostar against the milled reflector backside, on the bottom thermal grease is used to help removing the heat from the LED.
5) Todo
The whole assembly is still a little too high and the head will not screw together all the way. I will probably remove some more material on the inside and add some thicker O-Ring to seal the head. This does not affect the function of the light at all.
Electrical characteristics
The converter is in stock configuration, that means 100% output is 1000 mA to the LED. With the Remora the Shark is turned into a three level clickie at 10% - 50% - 100% output. 100% means about 20 W power at the LED, which is more than the setup can handle thermally. I plan to reduce max. output to about 750 mA.
With freshly charged Li-Ion cells (AW black 750 mA) i am measuring the following input currents to the converter:
Cells....Level.......Iin
2..........10%.......300 mA
2..........50%.......850 mA
2.........100%......3300 mA
Using the L4 body with 2 RCR123, the 100% level is drawing far more current than a standard Li-Ion can handle. The protection kicks in rather quickly as soon as the voltage sags too much and current going up. LiMn (AW IMR 16340) can sustain the high current though.
Runtime with two black label AW on 10% is 1 hour 40 minutes.
Light output
Similar as the stock L4, the modded light has a very floody beam with a very useful hotspot. Artifacts from the 6-die layout of the LED are noticeable on a white wall but not when using the light.
I don't have a way to measure lumens but from comparing with different other lights i can tell that not only it is wicked bright but also putting out much more lumens than anything else i have
At 10% the output is around 100 lumens, it is slightly brighter than the stock Lux V L4.
Check out the outdoor "beam shots" below, you can see that the floody beam is lighting up the whole area, i changed the exposure to make them look more as it appeared in reality.
On 100% it easily lights up objects that are further away than 100 m, but with the wall of light in front of you it is actually hard to tell.
L4 Ostar at 10%
L4 Ostar at 50%
L4 Ostar at 100%
Summing it up
I am amazed with the wall of light of the L4 Ostar mod, a nice floody beam. The lowest level is more than enough light most of the time, but when you need it you can crank it up and turn night into day. What makes all that special is the pocket friendly size of the L4 when it trumps many larger lights in light output.
If any of you can tell me what generation the KL4 head i have is, i would appreciate it. There is at least one other type of KL4 head/reflector that i have seen here on CPF.
If there is interest i might make a limited few mods for fellow CPF'ers, especially seeing as ARCMania has stated that he would not make any more of them.
Hope you enjoyed it!
The OSRAM Ostar 6 die emitter in its higher luminous flux bins is the emitter with the highest light output available today. So sure enough building a flashlight around this beast is more than tempting. Since i won't be lugging around a large torch on a regular basis, i rather wanted something small enough to be sort of an EDC. Lots of useable smooth light is what i had in mind and this is just what a multi-die emitter really "shines" (pun intended
) at. Full credit for the the idea behind this mod has to go to ARCMania who has pioneered building an Ostar into the KL4. While his great work involved custom parts like a pill to house electronics and hold the LED, i am making use of the existing parts of the Surefire L4 host. The KL4 is pretty much the perfect host for this project since it will tightly fit LED and converter with no room wasted.
The Build
Lets have a look at the list of parts that went into this mod:
- Surefire L4 (Lux V)
- OSRAM Ostar (Bin QY4C)
- Blue Shark converter with Remora controller (Sandwich Shoppe)
- Small piece of copper as heatsink for converter
- Wires, Polyimide tape, thermal interface materials
- DIY milling setup
1) Opening the KL4 head
The first step is far from being the easiest since the treads on the head are locked with a black sealant. Some people seem to have been lucky and not needing much force to open the head. This one needed both heating and a combination of a vice and a wrench to come apart. Using strong and thick rubber sheets wrapped around the head preserves it from getting scratched in the process.
Once this is done we are removing converter and the Lux V LED, it will probably end up in my small LED museum.
2) Milling the head for the Ostar
Looking at the parts at this stage you can see that the Ostar will fit the grooves on the backside of the KL4 reflector. For a perfect fit we need to take off some material though. I am using an ordinary drill in a rig and some small milling tools. To avoid any damage and too much debris inside the reflector i have masked things off with some tape. I also need two slots since the wires to the LED are running at the top of the MCPCB. Fast forward about an hour the head looks as in the picture below.
I also enlarged the reflector opening by a few tenths so the Ostar will go in all the way.
3) Other mechanical work
The "LED support" with its two screws will be used in the mod, but it does need two new holes for the wires.
The Ostar MCPCB needs to be sanded down to be slightly smaller in diameter than the inner diameter of the head.
Some more sanding is necessary on the converter boards to mate with the LED support and the battery contact part.
4) Assembly
Blue Shark and Remora are stacked as tightly as possible. I am using isolating polyimide (aka Kapton by DuPont) tape wherever unwanted electrical contact could be possible. A cut piece of copper attached to the top of the DC-DC converter chip will make thermal contact to the aluminium LED support.
A cut piece of polyimide shields the top of the Ostar against the milled reflector backside, on the bottom thermal grease is used to help removing the heat from the LED.
5) Todo
The whole assembly is still a little too high and the head will not screw together all the way. I will probably remove some more material on the inside and add some thicker O-Ring to seal the head. This does not affect the function of the light at all.
Electrical characteristics
The converter is in stock configuration, that means 100% output is 1000 mA to the LED. With the Remora the Shark is turned into a three level clickie at 10% - 50% - 100% output. 100% means about 20 W power at the LED, which is more than the setup can handle thermally. I plan to reduce max. output to about 750 mA.
With freshly charged Li-Ion cells (AW black 750 mA) i am measuring the following input currents to the converter:
Cells....Level.......Iin
2..........10%.......300 mA
2..........50%.......850 mA
2.........100%......3300 mA
Using the L4 body with 2 RCR123, the 100% level is drawing far more current than a standard Li-Ion can handle. The protection kicks in rather quickly as soon as the voltage sags too much and current going up. LiMn (AW IMR 16340) can sustain the high current though.
Runtime with two black label AW on 10% is 1 hour 40 minutes.
Light output
Similar as the stock L4, the modded light has a very floody beam with a very useful hotspot. Artifacts from the 6-die layout of the LED are noticeable on a white wall but not when using the light.
I don't have a way to measure lumens but from comparing with different other lights i can tell that not only it is wicked bright but also putting out much more lumens than anything else i have
At 10% the output is around 100 lumens, it is slightly brighter than the stock Lux V L4.
Check out the outdoor "beam shots" below, you can see that the floody beam is lighting up the whole area, i changed the exposure to make them look more as it appeared in reality.
On 100% it easily lights up objects that are further away than 100 m, but with the wall of light in front of you it is actually hard to tell.
L4 Ostar at 10%
L4 Ostar at 50%
L4 Ostar at 100%
Summing it up
I am amazed with the wall of light of the L4 Ostar mod, a nice floody beam. The lowest level is more than enough light most of the time, but when you need it you can crank it up and turn night into day. What makes all that special is the pocket friendly size of the L4 when it trumps many larger lights in light output.
If any of you can tell me what generation the KL4 head i have is, i would appreciate it. There is at least one other type of KL4 head/reflector that i have seen here on CPF.
If there is interest i might make a limited few mods for fellow CPF'ers, especially seeing as ARCMania has stated that he would not make any more of them.
Hope you enjoyed it!
