Newsletter 4

Design of a weatherproof enclosure for long-term data collection with environmental gas sensors

This week we continued working on our environmental gas sensor project. Our goals were to add solar power to the device and move the electronics into a weatherproof enclosure as we prepare for long-term data collection.  

Items used

FreeCAD designs

The first step was designing mounting plates for the electronics that will go into the enclosure. We used FreeCAD to make these designs which are on our Github site here. We designed two plates connected by standoffs. The TOP plate has a cutout for mounting the PyGamer and room for inserting/removing the SD card and accessing the on/off switch; the BOTTOM plate has mount holes for the battery, solar charger, GPS and BME688 environmental sensor.

The material used was 1/8" (3mm) thick black acrylic. The acrylic was cut on a laser cutter and the two plates are connected with 2" standoffs.  Standoffs, screws and zip ties were used to mount the battery and electronics to the top and bottom plates as shown below.

Image showing how the components are placed and connected
Final assembled version

The final assembled version is then inserted into the SE120 enclosure and secured with screws into threaded inserts which we added to the enclosure. Two small holes were drilled in the bottom of the enclosure for gas exchange and for the cable connecting to the solar panel.  The enclosure was then mounted onto a piece of extruded aluminum (1010 80/20). A threaded rod was attached for inserting the unit into the ground.  The solar panel was attached to the top of the 80/20 with a bracket. See pictures below for the final assembled unit.

Total unit cost so far:

The total cost of the unit is around $250 as detailed in the table below. We can easily add more sensors in the future.

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Next steps: We will collect data from this unit for 5-6 days and report on that in the next newsletter.

Bookmarks

Seahorse SE120 Waterproof Protective Case (7.5 x 5.0 x 3.2”)
Check out the deal on Seahorse SE120 Waterproof Protective Case (7.5 x 5.0 x 3.2”) at Seahorse Cases
FreeCAD: Your own 3D parametric modeler
FreeCAD, the open source 3D parametric modeler
6 Watt 6 Volt Solar Panel
The 6 Watt solar panel from Voltaic Systems is lightweight, waterproof, and protected by rugged UV-resistant urethane coating. Peak Output: 6.5V 930mA
Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger
This charger is the only one you need to keep all your Lithium Polymer (LiPoly) or Lithium Ion (LiIon) rechargeable batteries topped up. No matter the power source at your disposal! ...
Solar Panel Bracket - Medium
Mount your Voltaic solar panel using our large solar panel bracket. Compatible with Voltaic’s 2W, 3.5W 6W, and 9W solar panel.