beautiful light on the mountains

this morning. Time to start bringing the fuji on my bike? All the major peaks visible from Grenoble are dusted with snow.

Megalamp, the return

The project: Megalamp Mark III scuderia Sti. After my experience with the mark II: specifically lots of light, but the occasional piece falling off, I decided to make a new light. The idea was to make a water resistant, durable Lithium driven light that would use the excellent TaskLed Hipflex driver. Oh yeah, and while I was at it, I wanted something a lot brighter -- why not, right? So: machined Al housing, 14.8 V lithium pack, triple Cree MC-E, Reflector optics. I had been thinking about this for a while, but my bike commute on an unlit bike lane brought it back to the forefront.


housing: A very generous machinist made the housing out of Aluminum based on my specifications. I mocked up a model in Sketchup, but he went a step further and took my measurements and put it into SolidWorks and cranked the thing out.


Next, someone suggested anodizing, which I did:




optics: The choices for small optics for the MC-E that work well are a bit limited, but the Ledil Booms seemed like a reasonable choice. I haven't used reflector based optics because I didn't want to deal with a protective covering, but my lab contact generously made me a polycarbonate lens, so why not?!


output: Here are the Cree numbers for the MC-E for K bin: 370-430 lumens at 350 mA. Looking at their graph, it looks like you can get up to ~173% of the 350 mA light at 700 mA. IF you could run three MC-Es at 700 mA (like running 12 individual LEDs at this current), you would be making ~1920-2230 lumens! I plan on running at 350 mA to preserve battery and not damage things, so I can expect a paltry 1110-1290 lumens. This is ignoring optics, efficiency of the driver etc, so take it with a big grain of salt. Even with the salt, though, it's very bright, and when you consider the price of the parts (excluding the fancy case), it works out to be quite cehap compared to the 900 lumen $700 lights on the market.

Here are theoretical values, assuming 370-430 lumens for the K bin:

mA watts lumens
1000 9.3 833-976
1400 13.4 1110-1290
2000 20.4 1499-1742
2400 24.5 1721-2000
2800 29.4 1920-2231

not sure about the watt values, since I didn't take much time in my reading of Vfs off of the Cree datasheet. In normal operation I will be dimmed quite a bit, I think. I'll try 1400 mA to start with.


Temperature: At 50 degrees C, you lose ~ 6-7 % intensity, 75 degrees, 12-13%, 100 degrees, 18 %, so here's hoping all that Al dissipates the heat. Thankfully there is a temperature sensor built into the Hipflex. The other concern is decreased lifetime of the LEDs.

weight: 215 grams for the light + wire
247 grams for the battery + wire + case = lighter than the seca 900 by a lot.

Guiers

After spending the morning at the farmers market, stocking up on Olives, dried figs, Comte, Tomme, quince, apples, oranges , bread and other staples,

we went for a hike to the source of the Guiers in the Chartreuse. The damn "baby" backpack is really starting to do bad things to my shoulder and hips; although we are far from the official weight limit, I think that we might have hi the practical weight limit carrying Zoe (28 lbs). In any case, it was kind of a grind but led us to a very cool cave:

biking with Zoe

Today Zoe and I went to the famous super high end sports store called InterSport to look for bike seats. I had seen a lot of the Hamax style seats around and wanted to have a closer look. They have a convenient quick release mounted on the seat tube and after a little poking and prodding, we bought one with a five point race car style harness (I'm grooming her for a future in the World Rally Championship). I took a quick test ride

around the block with her and discovered that my long neglected mountain bike now had its front brake permanently engaged, which added to the effort required in getting us up even small hills.

After tuning up the bike, Zoe and I went for a much longer ride: up past the climbing site, then down to the bike path. We biked along the path, and I took secret delight in passing guys on racing bikes. Soon enough, however, I came across a long section of the path where large chunks were missing, which meant dropping 4-5 inches onto gravel and then back up the other side. It looked like they were removing roots or something, but it was pretty annoying. After about eight miles, I stopped, asked Zoe how she was, to which she responded "BREAD! CHEESE!", so I turned around. It was kind of a cold ride back.

21.5 miles -- pas mal!

What's this?

Is this a raw potato with the tooth marks of a two year old on it?  Why yes!  Yes it is!  Zoe managed to find the potato, bring it to us while saying "Tato?".  We didn't notice that she had tried to take a bite out of it until later.

Bouldering Peuil with vero, lolo and thomas

thinking of our friends in Toronto and hoping things are getting better

anodizing

I anodized the Al housing for the new light this week.  For some reason I found it difficult to find any concrete numbers on the various parameters involved, so here is what I learned:

try to use constant current instead of constant voltage (i.e. do not connect to a car battery).  When I monitored the current starting at the generally recommended 12V, it was in the 6 amp range for my part and rapidly trailed off.  Since the process that is occurring is the creation of an Al2O3 layer which is etched by the sulfuric acid (which creates pores into which dye can diffuse), the balance between acid strength and current is critical.  My part had ~ 160 dm^2 and I was shooting for 2 amps in ~10% Sulfuric acid.  Therefore, a massive peak current of 6A which trails to nothing probably does not deposi a very even layer of anodization.  The other thing I discovered is that it is best to use a new Al electrode every time, and make sure it is connected very well to your part.  I had two test runs where the current dropped to 0, and I assumed it was because the oxide layer was so thick that there was no more conductance.  I now think that it was simply the reused Al wire getting oxidized to the point where it could not contact the part any longer.  I cleaned the wire in NaOH every time, but that is probably not enough.

Notable things seen on the AM commute: an Electricte de France Unimog, probably off to do some repairs in the mountains, a recumbent bike with a fluorescent windsock, a traffic light on a freeway offramp about to cause a major pileup.

our little pointillist!

bouldering at Peuil

with Vero and Thomas.

Limestone bouldering!




deluxe baby accommodations:


and bouldering potential for the height challenged:





It's a beautiful time of year to be up there. The whole forest is covered in a thick carpet of brown alder (?) leaves, and you can see the giant cliffs that flank the Vercors in the background.

Meuliere

We made a second attempt to hike up the 'facile' loop trail that takes you past the ancient millwheel quarries above le Mont Saint Martin (last time darkness and baby crankiness overtook us). It's amazing to see the remains of ancient facilities where they hand shaped millwheels and then moved the 1 ton wheels down the mountain... in the 14th century!

There are amazing looking cliffs to the NE, none of which appear to be equipped


beautiful light as we got back to the car



and a sleepy Zoe

ice cream in winter

Grenoble has two (maybe more?) amazing ice cream makers: the place near the Jardin de Ville and Gonzalez. I have previously posted about some of the weird flavors that Gonzalez makes such as tomato, mustard and basil. Anyway, the boulangerie across the street just happens to sell tubs of Gonzalez ice cream. So far, I've tried the caramel with beurre salé and fleur de orangier (orange blossum). Both have been excellent and I am saving up my euro centimes for a ice cream cake!

clemenciere + proveysieux

mom gone :( !

lunch in town

followed by visiting the Grenoble museum, which is excellent. I should really try to take ZZN there more often. And by more often, I mean 'ever'. Somehow I only seem to visit museums these days when the parents visit!

tour de sens, Chambery

My mom and I went to the Tour de Sens (on the way to les Sept Laux), where we had a fantastic meal:

Some kind of carrot foamy thing on a layer of caviar. Like a fruit on the bottom yogurt, but with caviar, and no yogurt.... I couldnt really understand what was being said.

Trompette de mort mushroom (love that name) mousse with butternut squash soup

puff pastry with chorizo and shrimp

some kind of delicious fish (mullet?), cooked perfectly

MEAT and the best french fries ever. I have no idea how they cooked them, but they were perfect. I suspect duck fat was used. The pasta were perfectly cooked too, of course.


Tiramisu on a pear crumble


yogurt lemon emulsion with candied citrus at the bottom.


We could barely move after the lunch

but pressed on to visit Chambery. I had never been to the old town, and it is wonderful!



Then back home via the Chartreuse (D1006) and St. Laurent du Pont. All of this was on Franck's recommendation. Thanks, Franck!