Hey everybody. Hope everyone is doing well. I just have a couple of questions about an upcoming project.
First, let me give a short background on my knowledge of electronics and software. I got my degree in computer science, so I’m much more comfortable as a programmer than I am an EE. Until about a month ago, I really didn’t know much at all about electronics. But I’ve bought a couple of books, ordered some parts, and gone through the tutorials here at SparkFun. As a result, I am a little more comfortable with BASIC electronics concepts.
To further my knowledge, I am considering (with a coworker) working on a project to log weather conditions. I know SparkFun sells a USB weather board, but I feel like I’d learn more if I bought the individual sensors, learned how to work them one at a time, and then tie them all together in a project. The project I’d like to do will consist of ambient temperature, water temperature, humidity, and barometric pressure. I figure for ambient temperature, I can just use the basic temperature sensor sold on SparkFun inside the project box. I know some heat will be given off by the electronics, but I hope that it will be negligible. My #1 question is for suggestions on how to mount the humidity/temperature sensor sold on SparkFun (or somewhere else, if you know of a better sensor). I assume that the humidity sensor would need to be in open-air conditions, and not tucked away in a project box. If this is the case, can anyone provide any suggestions on the best/proper way to mount such a system so that the project enclosure can still be weather-proof/resistant?
If you need any more information, please let me know!
I have a $150 La Crosse weather station that has a PC interface. That PC collects weather data and uploads every 15 minutes it to a web site database where thousands of other weather fans do likewise. That website displays weather history data as tables or graphs.
I wrote my own software to grab all the data and format it to send to the web site. Runs on an always-on PC in the garage. Other people use canned software to do this - but that software is a CPU hog.
I also log all weather data to a microsoft MDB database on the garage PC. And I have a web server to display the current and last few day’s weather data (highs/lows, etc)
The data includes wind, rain, temperatures, pressure, etc.
The weather station could just as well talk to a microprocessor - given you know the data formats. for the La Crosse, a group did reverse engineer the formats and I use a version of their C code libraries to do so.
My ultimate goal is to build this system from the bare sensors, up. I’d like to first learn to take sensor readings one at a time, starting with the temperature sensor wired into a breadboard and then move up from there, to a perf board and, ultimately a PCB (when I have learned to communicate with all of the sensors). This project is to be used by my brother as a means to make predictions on the best time to conduct specialized hunting trips. After data is collected, it will be uploaded to his home computer where custom software will store it and perform statistical analysis on the data and compare it with the weather forecast to try and predict the most optimal day to conduct a hunt. I’m doing it (primarily for me) as a means of learning low-level programming of a microcontroller and interfacing with sensors.
There are two main issues regarding mounting temperature and other sensors outdoors. The first is regarding whether the sensor and associated electronics are operate in such a environment.
Many electronic components are only tested / certified to operate in a limited range (ICs may be designed or certified to operate in a “Commercial” range which is often 0-70 degrees Celsius, Automotive, Industrial, Extended and/or Military are typically available to operate over a wider range of operation, at additional cost). Many electronic components operate within a limited range of humidity, or are not waterproof.
So the sensors and local support circuitry much be protected from the elements. This can be done with selecting appropriate sensors that can operate when exposed to the weather conditions you plan to operate within (i.e. Thailand and the Yukon have very different climates).
Next is to select cabling, plastic or metal housing (case/ box) that is waterproof, including correctly sized grommets for holes needed for cabling / power.
Second is getting an accurate measurement, not influenced by factors such as solar radiation or wind chill. The classic way meteorologists do this is to mount their instruments in a [Stevenson screen.
on the weather underground website/forum (see above) you can see folks who have made their own Stevenson temperature enclosures - using a stack of plastic plates. The La Crosse and other products come with a small cheap-o one.
this yahoo group has lots of chat about such things