2015-07-06

Temperature & Humidity monitoring - update

Back working on the temp sensor that I started in http://lpaseen.blogspot.ca/2014/11/temperature-humidity-monitoring.html

Two prototypes have now been running over 5months on same battery so my fear that I have to replace batteries every 2 weeks is gone.
With that in mind I moved on and made a PCB to place all parts there. First try came out ok.


I then put it in a small box with 2xAA battery. The booster is a separate board and that is something I don't like. Will probably make another board+box and use 3xAAA in it so I don't need a booster.
It's a lot left to desire for any kind of final version. The booster is annoying and I wonder if it's better to run off 3 batteries instead. The advantage of the booster is that it suppose to work as long as the two batteries together gives more than 0.9v. On the other hand, it takes power and space. I don't have a good enough multimeter to properly measure how much it takes so I can't test it that way. What I do know is that the sensor with 3xAAA NiMH and 3.1V left is still running after 5 months. The one with 2xAA NiMH and booster been on for almost 6 months and with 2.45V left I expect it to run a bit longer.

Besides battery my other issue is wireless range, was hoping for a bit more than the size of the house but that seems to be tricky. If I put the receiver in the basement and transmitter in attic it doesn't work so I moved the receiver to the middle of the house and then I can get my (way to high) attic temp.

I'm considering making another version without a arduino board, just the atmel chip (which one, atmel328p, attiny85 or something else?), SMD, ISP connector and voltage booster onboard (with the option to not populate it if going with 3XAAA). If so I can of course no longer get a way with toner method to make my own PCB and need to order it from somewhere, http://dirtypcbs.com/ that has a $14 protopack for 10 5cmx5cm boards looks interesting.

Next we have the presentation side, right now it's just storing all values in a .csv file. To get something going I'm trying to upload about one week of  data to plot.ly so now I have temp&humidity at https://plot.ly/~lpaseen/306 and battery level at https://plot.ly/~lpaseen/309

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