~This page dedicated to Unforgiven ~
The original River Rock LED lantern was a great Target buy a while back. $20 maybe? These high-quality, durable 4xAA little lanterns are quite handy for camping and general lighting except for the terrible UI that they ship with. The lantern only offered HIGH, blink and off- no dimming! And to turn it off, you must cycle through blink every damn time. Ug. The solution was a driver replacement, and nFlex was the best fit - it is lucky I have a stash of George drivers here! Now the lanterns have eight levels, and will turn off by themselves if accidentally left on. While I was messing in there anyway, I decided to make some other modifications to improve the output. I modified two units. One I left with the factory 360 ° output and upgraded to SSC P4 (U-bin) emitter firing down, in the factory configuration. The other lantern (thanks Tom!) I made into a 180° output "forward" light and upgraded to a Cree XR-E (Q5 bin). On this one, I put reflective tape on the rear wall of the globe and fired the emitter directly out the front of the globe. On both, I frosted the globes and put a cone reflector on the bottom. I removed the silly internal secondary dome and cone reflector that come with the lights - they just get in the way and reduce output. There are videos of the UI in action at the bottom of the page.
First, the result. Unit on the left has the forward-facing
Cree. Because of the more efficient emitters and extra heat-sinking, I'm running
these at a 500 mA max scale. They're on high here.
Here the Cree unit is on the right. You can see that
it puts quite a bit more light forward... but none to the back. both beams are
just about perfectly uniform. GREAT for reading.
Here is what the inside of the lantern looks like
from the factory. The down-firing emitter is behind a plastic dome, and a small
cone reflector hangs down on two plastic pillars. Most folks realize that the
ringy output of the factory lamp is pretty annoying.
The following are pictures of the process for making the down-firing unit and the front-firing unit. They're all pretty mixed up at this point, so hang on. We'll start with taking the factory unit apart.
Once the cap is twisted off the nuts can be unscrewed
and the goodies just pull out. Only thing I reused is the heat sink.
Next the dome and cone reflector units soft of "unscrews"
out.
And the shiny holder for the above unit literally
falls out.
This gray plastic button collar is held into the
rubber button under the top cover by friction. I removed it and nipped the edge
off to make it fit flat onto the nFlex. I epoxied it into place once I made
sure it would fit under the lid. The edge of the board is rounded to help it
fit (snugly!) into the top of the lantern.
With the gray collar affixed to the circuit, the
collar can then be stuck back to the button to hold the circuit in place. Shown
in this shot is the plastic removed from the shelf that holds the circuit. This
allows the cap and inductor to hang down into space. This was the part that
I though was going to kill the whole project! But it fit! You'll also see here
that I drilled holes into the heat sink since the sink had to be rotated 90°
to allow clearance for the circuit components.
Here is the Cree forward-facing LE. This hangs upside-down
into the globe. I added a finned sink to the back. I can run this at 500 mA
and still touch it.
Sink is in place, and the LED is wired to the nFlex.
If you are paying attention at this point, you may notice that I had to file
some material off the sink to fit the circuit. I then installed the wide part
of the sink on the side where I did NOT remove plastic from the shelf. Didn't
realize this until I had it almost all together.
The forward-facing Cree LE going into the sanded
and reflectorized globe.
The original circuit sat on these power posts and
got power directly. I have to use wire, so I first made some soldered loops
to go around the posts - and then tightened it down with the nuts. Be sure to
insulate that heat sink before this step!
I literally sanded the globes on the inside. Easy,
and works perfectly.
I started with a clear globe and a reflector in
the back. Didn't like it! This also again shows the modified upper shelf where
the new nFlex will go. And it shows the SSC down-firing LE. Additional sink
is added directly behind the emitter.
Reflective tape on a sanded globe.
The nFlex wired to the down-firing SSC LE. Good
view of the enlarged holes in the sink needed to fit over the plastic bolt holes.
Better shot of the extra sink on the back of the
down-firing LE.
Before frosting the bowl I took a shot of the nFlex
in place. The blue foam is to insulate and keep the board pushed up against
the switch membrane. You can see why I had to carve out the pocket in the upper
shelf now. All those "electronic things" that George insists on installing
on his circuits needed some room.
And finally - the video of the new lantern functionality.