The McR-8 (8 mm) was designed for small LED dies and with the intent of concentrating the light in a reflected beam with a relatively tight flood angle. The reflector has a 3/8" OD and is also 3/8" deep. Below it is shown with both a Nichia Rigel SMD LED as well as a Nichia 3 mm (310) LED .
A custom AAA light was designed to host the McR-8, a Wayne Yamaguchi "Tuna" dual level constant current driver and a Rigel LED. The SMD LED was mounted directly into the brass head with its cathode pad soldered to the bulkhead. A milled relief isolates the anode pad from the head and allows access to solder a lead wire to it. The anode "cavity" was potted after a lead wire was attached.
This light has four milled slots in the tail which host tritium vials visible from the outside as well as through the counter bored tail. A mineral glass window seats against an O-ring which is compressed until the window also contacts the reflector. The window is held in place and compressing the O-ring by a brass bezel which was pressed into the head. The low current is around 20 mA and the high current to the LED is somewhere between 150 and 200 mA. Flux was measured at .8 and 8 lumens. The output is very comparable to a new Arc AAA which also measured 8 lumens on my equipment. The beam patterns are different though:
The light is shown in the left frame on low and in the right frame on high with the Arc AAA on the left in each frame. The two lights:
A completed circle of titanium chain was added to the tail to provide a short finger tether or means of hanging or attaching to the light.
The McR-8 has a .100" opening at the base and this was bored out to 3mm to accept a 3 mm Nichia snugly. The "310" has a wide viewing angle which means that a good portion of its light output will be redirected by the reflector. A Pelican L1 served as a host and the stock 5 mm Nichia was removed and replaced by the 3 mm.
The stock Pelican L1 has a beam comparable to the Arc AAA as they use the same 5 mm LED. A beam comparison:
Both the Nichia 3 mm and 5 mm LED's use the same die. The McR-8 optic package coupled with the 3 mm is not as efficient as the single integrated optic of the 5 mm standing alone but a more concentrated and intense spot as well as flood beam is possible should this be more desirable at the expense of efficiency.
Lumiled's PWT LED:
Of the three LED's paired with the McR-8 reflector, the Nichia 3mm seems to have the best efficacy but the best beam of light in terms of distribution and tint consistancy is had by the PWT. As with the Rigel, the PWT was solder mounted to the brass connecting the cathode of the LED to the mass of the brass for thermal relief. a steped down counter bore left a crescent shaped shelf that the LED was soldered to and then a through hole was milled for the anode lead to exit withoug contact to the brass.
With a drive current of 200 mA, the PWT measured 8 lumens on my equipment which was on par with the Rigel which is driven somewhere between 150 and 200 mA. The Nichia 3 mm puts out 8 lumens behind the McR-8 with 100 mA of input current.
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