Sunday, May 31, 2009

The Eagle has landed

Once I got started in Eagle I got a little loony. Hours go by in a flash as I work at a sub millimeter level routing connections and sorting out placement issues. It's kind of like a very seductive puzzle. I've now laid out three different circuit boards in Eagle, and it feels like I'm getting the hang of it. Two (motherboards) are based on the Arduino Mega reference design, and the other is a shield (daughterboard) that could be used with most Arduinos. The first board is what the heliostat needs, but the other variants use cheaper components that may be of interest to others (and thus are potential spinoff products). After several frustrating hours I think I've been able to source nearly all the necessary components. Mouser Electronics will sell SMD resistors for 5 cents each compared to 50 cents from Digikey! Seeedstudio's Propaganda PCB service will make the prototype circuit boards for only $5 each. I've followed several tutorials from SparkFun and I feel ready to stencil the solder paste and cook up a few boards on a hot plate. Quite the blend of low and high tech. If no major issues pop up, then the Gerber files will go to manufacturing later this week.

I went to Houston for Srila Narayana Maharaja's Bhakti Yoga Festival, although I was a couple days late because I listened to the advice of everyone around me and avoided the potential DUI checkpoints that were setup for the Memorial day weekend (since I don't have a valid drivers license at the moment). This was of course just another one of Maya's tricks (Maya - that which is not) trying to impede my spiritual progress. I was feeling kind of weak and nauseaus before I left, but immediately felt better once I got on the road. Nothing in this world compares to the mercy of the vaisnavas and the delicious prasadam at the festival.
I tried talking to various people at the festival about the heliostat project, but it seemed nobody had an understanding of the implications, or any interest in helping. At the very end of the festival, I sat down at a table by myself, and another devotee sat down and after a while we began talking. He was interested in my story, and offered to give me his old laptop (which should be fine for coding). This was yet another excellent example of the following principal: although we must make an effort (endeavor) to achieve something, success is not due to our own efforts, but rather the mercy of the Lord (and his personal representative - Srila Gurudeva).

While I was gone the 30x40 fresnel lens I ordered arrived. A quick test outside showed about a 8" long focus point (this is a linear lens designed to focus light into a line instead of a point). This quickly smoked some grass and made some mysterious stuff bubble out of a rusty scrap of metal I found in the yard. I have my doubts about whether or not this is more efficient than a parabolic reflector, but it is certainly practical for concentrating light on something like the heat tube of an ammonia refrigerator.
I'm still trying to decide what is best as a first target for testing the heliostat on. The refrigerator is "cool", but some sort of water heater would allow easier calculation of BTU/hr, thus yeilding effective wattage level.

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