Thermomitor

They say nessesity is the mother of invention. While I belive that is very true it would seem that the need to prove yourself is the father of nessesity.

One day we had commented to dad that it had froze last tuesday. He expounded adamantly that it dose NOT! freeze in August!! My story of white crunchy grass and scraping ice off the windshield did not convince him.

So off to Ebay I go...

I bought myself a DS18b20 digital temperature sensor. He was ok with the documented accuracy spec of +/- 0.5* C.

I then connected that to an Arduino with a cute TFT display (for asthetics, Mrs delusional Mechanic says that asthetics count.)

Also connected to that is a Data logger witch will log time and tempurature every hour to the SD card.

With proto type working on the bench it was time to add the prettiness, if thats a word.
I needed a case so off to openSCAD to design a box.

While the printer was busy printing I made a new wire harness that was little bit more simplified. Note that I have the data logger directly mounted on the Mega but I did have to cut off the pins 11, 12, 13, A4 and A5 as they are not compatable between the uno and Mega. *Still has imprint of hands in forehead from counless hours of faceplanting and dry throat from yelling WHY dosn't it work!!!!*
Then I put the put all the tiny bits into the box.

Final product.

With the unit all up and running on a chilly december morning it is reporting -24*C !!! My phone and the internet say the local temp is -14*C ?!?! Is the thing defective? Did I just biuld a POS?
My wife, still a bit skeptical,( OK she exclaimed IT LIES!!!!) puts on her boots, grabs a flashlight and goes out to the far shed where the alcohol thermomitor resides,scrapes the frost off of it to find out that it too claims -24*C. Hmmm. I wanted to say... And then I thought better of it.

Now when Dear ol' Dad says it did not freeze last night I can take the SD card out and E-mail it to him.
*As an added feature it creates a folder with the month name and I also changed the file extention to .CSV so all he has to do is double click it and it will open in Numbers all set up in nice neat collums with time and temp.

(Fun fact of the day--- The stupid thing stopped logging at the end of august. I couldn't figger out why. 4 days later I was about to email my highschool buddy (proffesional computer programmer) when the thought occured that the SD card has to be formatted FAT32 and as such can only have an 8 character filename. DOH!)

So my loving wife says " Black! why black?! Get some plastic in a better colour and fix it!"

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