With this light I wanted a big powerful thrower. Available hosts didn’t provide exactly what I wanted so I started playing around with some design ideas. 7 C8 reflectors fit nicely in a 5” circle, so I looked through online metal shops to find suitable material and with the help of machine shop access I put the light together.

 

It has 7 dedomed XPL V6 1A emitters powered by 2×26650 cells in series. The emitters are in 4p-3p configuration. The electrical setup is the same as my 7xXPL convoy L2 mod. It pulls right around 15A on fresh Liitokala 26650s. It does around 8800 lumens at 15sec and 739Kcd at 30sec (measured at 10m). The beam is practically the same as a C8 with dedomed XPL.

Here are the parts layed out. The emitters sit on a 1/4” thick 5” diameter Al plate. The reflectors are housed by a 5” OD Al tube with 1/8” wall thickness. I made a flange which bolts to the bottom of the plate and has a threaded connection for the battery tube.

Here is the flange being made on a lathe. I made the internal threads on the flange and tailcap with a tap (1 1/4”-12) and cut the external threads on battery tube using the thread-cutting function on the lathe.

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Here I’m test fitting the reflectors in housing. The reflectors had to be shaped a bit in order to fit in the available space. I did this by hand with a file so the angles aren’t perfect. The top of the housing has six threaded holes which allows the lens to be tightened down on the reflectors.

Copper disks in the flange and tailcap make contact with the battery tube. In the tailcap the copper disk is electrically isolated from the Al tailcap itself so I can lock out the light by unscrewing the cap by a turn. These connections are sealed with orings on the battery tube.

The copper disk in the head rests against a small hollow spacer (I used a 26650-18650 converter). The 17mm driver ground ring is soldered to the copper disk. The driver itself is an old mtn FET driver I had. It’s hard to see in the picture, but I piggybacked a small 5V regulator to power the MCU in order to get low stand-by current. Capacitors in the “C1” and “Zener cap” spots on the driver board serve as input and output capacitors, respectively, for the regulator, as recommended in the datasheet. I have ToyKeeper’s e-switch ramping FW flashed on the attiny13.

I attached the housing to the head plate using JB weld.

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The e-switch is a small unit I bought from radioshack. It is covered with silicone (RTV gasket maker). It doesn’t look pretty, but it works to protect and waterproof the switch. There are 6 28mmx28mmx20mm heatsinks attached to the back of the emitter plate. I haven’t done any extended on-time heat testing, but I think the heat-handling should be relatively good. The heat spreads from the plate to the housing well, and the thermal path from emitters to heatsink is almost ideal in this configuration.

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Here it is compared to a convoy L2 and C8. It is fairly compact height-wise, but of course the head is very large. As it is now it weighs 980g with 2 LK 26650s.

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Here is the view from the front. The lens is UCLp from flashlightlens.com. A problem I didn’t anticipate was caused by the flexing of this plastic lens. When the bezel is tightened the lens bows up slightly in the middle and doesn’t press down equally on all reflectors. I put some spacers on the center reflector to mitigate the problem, but it is not ideal. I need a stiffer lens. I plan to seal up the front parts by making gaskets out of suitable rubber sheet material.

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This light really deserves some long-range beamshots, but I don’t know when I’ll get those. Thanks for looking!

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