\@writefile{lof}{\contentsline{figure}{\numberline{1}{\ignorespaces Cut out with pliers and reuse parts.\relax}}{6}}
\@writefile{lof}{\contentsline{figure}{\numberline{1}{\ignorespaces Cut out with pliers and reuse parts.\relax}}{6}}
\@writefile{toc}{\contentsline{subsubsection}{\numberline{2.3.1}Ripped off by temperature sensors}{6}}
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@ -190,6 +190,57 @@ I decided to route out some of the pcb, so I can possibly reuse the temperature
\includegraphics{../pics/modular_reusable.jpg}
\includegraphics{../pics/modular_reusable.jpg}
\captionof{figure}{Cut out with pliers and reuse parts.}
\captionof{figure}{Cut out with pliers and reuse parts.}
\subsubsection{Ripped off by temperature sensors}
The community around Arduino advertises the LM35, advertises the MAX6675. The latter is \$10 in one off quantity (\$5 from ebay), the former isn't cheap either, at \$2.00 about. Though the LM35 has a much more limited range. The LM35 is great as it's extremely simple to use (power and read voltage which converts directly to temperature).
I'll have to find an alternative for the MAX6675. At \$10 it's just stupid. A micro can do temperature as well. Maybe \$5 would be acceptable, but \$10 is not. How big are your pockets?
\captionof{figure}{technoblogy has an article on using a micro with an external thermocouple}
Cheapest thermocouple on Digikey, is a digilent (they just import) thermocouple at \$10. Next is a DFRobot (chinese adafruit) at \$30 with a module included. Thermocouples are not cheap! Onto ebay.\footnote{Thermocouples: I forgot how they work today. I've read of them before but haven't used them much (have seen them in toasters. Now that I know they are worth \$5-10 I'm going to start retrieving them from broken toasters). When two dissimilar metals are put together, and then the metals are heated, you can get a voltage across them. This voltage can be read with an ADC. This phenomenon has a name, but the name is not important. Names just add another thing you need to remember. Bad idea. (OK, I remembered it, now I can fool myself into feeling intelligent - seebeck effect. Now let me go count my hertz, and volts, and teslas...) Wikipedia calls it the thermoelectric effect.}
After some research I decided to go with the Digilent probe. The cheapest used probe on ebay is \$10. I don't want the new ones from US, which is only \$5 cheaper.
\section{Bom Notes}
I should try to get rid of some expensive items where possible.
\vspace{0.2in}
tantalum is \$1. Try a ceramic.
MAX6675 is \$10.
Slide pot is just for fun. That can be removed.
\vspace{0.2in}
On the subject of boms, I have made two. The LT portion is complex, and requires its own bom. The rest of the items are on a different bom. I keep some things in stock so a few items have been omitted.
\subsubsection{SOD323 (diode) is equal to 0805}
Looks like the SOD323, diode / SC-73 package is near the 0805 package in size. SOD323 is slightly smaller, but not by much. They are probably interchangeable in practice.
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5 years ago
