The godess of cats accepts your devotion

But there is no need to be so loud and vulgar in your devotion. Please, grovel silently.

Lightbox Construction

Yet another update (01/16/2009): It worked! My sister reports feeling much better.

Update: For more facts & numbers, see my follow-up post here!

My sister suffers from seasonal affective disorder, also known as winter depression. A commonly prescribed therapy is light therapy - about thirty minutes of bright light in the morning. Bright in this context means more than 10 000 Lumens. You can of course buy commercial light-boxes, but I wanted to construct one by myself...

Behold, the DIY receipe for your very own Lightbox!


You will need:

• A load of  light-bulbs - I used ten 23 Watt flourescent bulbs which were advertised as the equivalent of 130 Watt incandescent bulbs. Anyway, we are interested at the amount of light they put out: 1560 lumens each. The light colour does not seem to be very important, according to the literature dealing with S.A.D. - just avoid daylight bulbs that emit UV.
  
  
• A box - I used a cheap Ikea Mackis plywood box. It's height fits the bulbs I choose perfectly, and you can get up to twelve of them into it. Above to the right you can see where I tried to figure out the placement of the bulbs.
   
• Bulb holders and cable and a plug - the cheapest ones, the holders won't get very hot.
   
• Some way to drill the holes for the bulb holders into the plywood. I used a drill that is meant for use with floortiles. Not perfect, but it worked.

After you have figured out the placement for the bulbs, drill the holes into the bottom of your box. It is not necessary for them to be very neat, since they won't be visible afterwards.

Then find a way of making the interior of the box reflective - if you are cheap and lazy like I am, a bit of aluminium foil will do. If you are awesome, you could drill holes in mirrors or something.

Next on: fitting of the bulb holders and cabling. Use some non-shrinking adhesive to secure the holders - I used "Konstruktionskleber", you could use silicone as well, I guess, or some epoxy. Then you want to connect all of those bulbs in parallel.

Here cabling is finished, and the first test has commenced. After thirty minutes the air inside the box was warmish, but in no danger of overheating and melting the bulb-holders or setting fire to the wood.

When the box is operational, and you have checked your cabling for short-circuits waiting to happen (exposed leads and so on) , it is time for cosmetics, i.e. hiding all the cables from the casual eye (and from not so casual toddler-hands).

Simply glue the top of the Ikea box on the back - if you have measured and planned carefully, all those cables should have place beneath it. If you haven't, it is time to curse and get out something you can use as spacer. I was lucky, though: everything fit.

And here it is, in all it's glory:

Yes, it is bright. Flee, oh demons of depression! Flee the holy light!

Christmas Haul: Coffee Grinder

My sisters, who may just be the most wonderful sisters in the world, not only read my blog, but noticed that in this post, I bemoaned the lack of a proper coffee grinder in my household.

Behold: His Grindingness!

Ohh, the smooth uniformity of the grind, the steady, unyielding churning of the crushing mill, the elegant simplicity of the mechanical timer, which eschews all unnecessary electronics...

Excuse me, I think I am going to have another coffee.

A harmonious Christmas

They are only playing.
Really.

On the road

Today I am on the road, nearly a thousand kilometers back to my parent's in Kaltenleutgeben, near Vienna. Here is a photo of my car-battery for your amusement. It is sitting on my floor, slowly charging on my pitiful 750 mA charger, because it went flat out of scorn for my neglect: In winter it pays to actually use your car from time to time, even if you'd rather take your bike to work.

Preparing the Plants

... for two and a half weeks absence. In the summer I tried to go with bottles of water connected by strips of cloth. That strategy backfired, capillary action failed me and my little palm-tree nearly died.

It is still not entirely recovered - as evidenced by the sad brown leave on the right. The farn and my Ficus benjamina (cunningly hidden behind the Elephant's foot, which is doing very well, thank you) are also ailing yet. So this time I am going with the humid-bathroom method, the well watered plants above a few centimeters of water in the bath-tub.
Should be alright, especially since there is no light, and the temperature will be around twelve degrees .

Back from the pit

A sudden urgency overcame my resolution to post (semi-) daily last week: The dreaded annual report. But now it is done, behold:

 

No, this isn't some innovative new form of writing your report, this is a worlde of the fifteen-page monstrosity I produced. Which I had to cut down to six pages afterwards, because (as I learned) this is the upper limit for annual reports at the EPFL. Figures. I'll put up the whole thing to read here as soon as I have finished finnicking that last graph.

Rings & Riches

For yea, his hand doth overflow with the riches of the earth...

I got more Macor-rings from the workshop today. They made me promise that I would take better care of them this time, because they are expensive and hard to machine - so I lied and said yes.

I guess I am just evil that way.

Gobi desert

Nothing to say, have a photo instead.

Taken with my old Minolta Z1 from the transsiberian railway, back in 2005. ISO 50, f/3.5, 1/125s, 38 mm equiv.

iBrick Mk. II real world performance

About two weeks ago I built the iBrick Mk. II, an external battery for my iPhone. I calculated it's capacity to about 5000 mAh @ 5 V, assuming eight 3000mAh NiMh rechargeables. This would mean an extension of the iPhone's battery life of around a factor of four.

Unfortunately I did not have eight 3000mAh batteries - those buggers are expensive! So I had to made do with six 2500mAh and two 1200mAh accus,  sub-optimal since you shouldn't mix capacities. To make up for it, I gave the iBrick the iBrushed-Metal upgrade, which you can see on the right.

On Saturday morning I charged both the iBrick and the iPhone completely, and used the former exclusively to charge the latter until both ran out of power on Thursday morning. Normally my iPhone lasts me about a day and a half, so the iBrick lasted for around three and a half days, or a bit more than two complete recharges. That looks promising,  and yesterday I bought two more 2500mAh NiMhs, so I can see how much the low-capacity ones dragged the rest down. Stay tuned for more exciting updates about the iBrick!

In the ball-park

On the ninth of October I bemoaned the fact that I'd have to redo nearly all measurements of 2008, due to a nasty reasonance that changed the voltage I was measuring by a factor of 2 to 10, depending on the setup. I said it would take about two to three weeks.

Ha!

It is only now that I have really figured out what was going on, and finally have redone the most important measurements. and this time I am sure, because lo and behold:

The red curve is mine, the rest of the graph is from Lisovskiy and Yegorenkov: "RF breakdown of low-pressure gas and a novel method for determination of electron-drift velocities in gases", Journal of Physics D: Applied Physics, Vol 31 (1998), p 3349-3357. Not exactly the same curve to be sure, but that is to be expected, especially since he used stainless steel electrodes, and I use aluminium ones.  

Totally different ion-induced secondary electron emission coefficients, dude.

Small bruise

In the spirit of total disclosure, and also to show all the girls out there how incredibly tough I am (you have my email, ladies ;), I have to amend yesterday's post. It seems that I have, in fact, sustained a small bruise on the knuckles of my right hand, which I did not notice until this morning. This illustrates that when you punch somebody, you really should take care to hit only with the first two knuckles of your hand (index and middle finger), which are much tougher.

There, now you have learnt something today. Punch away with confidence.