The cheap sensors are 2x closer at detecting change as they are at absolute temperature.
If your school has an Electronic Engineer department or a Physics department then check with them, they might know or cook up something you can use.
A pyrometer is based on rock that electrically polarizes when exposed to heat with the amount of polarization dependent on the temperature, sensitive enough to detect body heat. The expensive part is the electronics to read that as absolute temperature yet a PIR detector that uses the same principle gets around that expense by comparing output from 2 different pyrometers to look for difference. Suppose you had one looking in the hive and one outside, then if you have outside temperature known closely (1 expensive sensor) you can work with the comparative readings of many cheaper sensors inside versus the well known outside -- which would need calibration. You won't be able to use the PIR movement sensors as the two eyes on those are too close, but the principle may be something the physicists and EE's might get their own project out of.
kasslloyd:
afremont, thanks for taking the time to look over my proposal. I'm expecting to know if I get my full grant or just partial funding (which probably can't support 3D temp profiling, where full would) by the end of the month. I'm going to need assistance in designing circuits, or boards. I have some help already but any and all people who want to help with the project is welcome. I want to keep this thread going with updates as we go and all relevant circuits, boards, files and code to help anyone else who wants to do what I'm doing.
I agree that bees definitely need studying, they're EXTREMELY important for the health of our plants, ecology and us! Plus even if this isn't ground-breaking research, its good for undergraduates to learn the process of experiment design, data collection, and analysis.
With the sensor it should have a variance of 0.5C, correct? Would calibration of each sensor help? Is each off a specific amount that could be corrected if you knew the offset? Or is it random/variable?
Ultimately the range I'm looking for is 33-36C or 34-35C. It's a fairly narrow range, but it's not fractional of a degree but whole degrees. Obviously I need high precision sensors, but I can't afford EXPENSIVE sensors. The $1/sensor range is about my limit.
I would plan on calibrating each device before installation so that you know what the real temp is. Accuracy and precision are two different things, you probably already know. The sensor might be off by a fixed amount from .5 to 3C depending upon the specific sensor resulting in fairly poor absolute accuracy, but precision and relative accuracy might be very high in that a .1 degree change really is a .1 degree change to a high degree. I think you'll care a lot more about the fractional degrees than you might think. Once you graph some logs of temps measured to a tenth of a degree you will see interesting cycles in the data that you would otherwise have missed.
The linear sensors like LM34 and LM35 are 10mV/degree so if you have mV resolution with the ADC you can get 1/10 degree readings. As long as the measured temp is less than about 110F, the LM34 can be read using the INTERNAL ADC reference getting you .1F resolution. That's what I do for my indoor sensor. You can always create and expanded scale for a narrow area by amplifying and shifting the signal from the sensor. The Dallas 1-wire sensors give up to four bits after the decimal place for a resolution of .0625 degrees C.
First step, crazy me spent like a day and night figureing out Fritzing, and attempted(?) to create a shield for a Uno that will serve as the weather station.
It's obviously conceptual, not built, don't have the parts, just melding a bunch of circuits together to get one board.
Has a separate board that will hold the SD card and a OLED display for quick view of the weather/time.
Has header to link a GPS module to use to get accurate time.
Has RTC chip
incorporates all the sensors discussed so far:
RJ-11 jacks for the wind speed/direction and rainfall sensors
Barometric pressure I2C breakout board
Light sensor
Three DS18B20 (one on board and two headers for off-board water proof sensors, one to be a wet bulb sensor, and one for soil temp)
The humidity sensor SHT75 was suggested would probably interfere with the other I2C sensors, so a I2C multiplex chip was added to separate it out on a separate bus (PCA9540BD)
More eyes I can get on this large circuit the better.. the breadboard layout is how I built it, so it's somewhat make sense there, I can't figure out how to get the schematic view to do the autotrace, probably need to rearrange the stuff far better then I have. The PCB view though works, and I tweaked the silkscreen layers, added some logos.
Started learning Diptrace now, so I've uploaded the board as a Diptrace version. Noted that I had some wrong packages for chips in the Fritzing format, so now everything is even better, lol.
Hello i saw your topic. I am interested in something simpler. I want the board from GSM beehive scale with functions hive weight, humidity, ambient temperature. Please help me! Thank a lot!
I want to keep this thread going with updates as we go and all relevant circuits, boards, files and code to help anyone else who wants to do what I'm doing.