With the first version of our DIY board we developed a simple 3D printable enclosure with a wall mount that looks like this:
Problems with the old enclosure
In general it worked quite well but there were a few problems:
Inaccurate temperature reading
Due to the compact nature of the enclosure and the SHT30 temperature sensor being in very close proximity to the PM sensor and also the Wemos D1 that radiate heat during operation, the temperature readings were too high (1-2 degrees Celcius).
As a result some people used a correction formulae but this is not idea, e.g. if there is air flow, it might then underestimate the actual temperature.
So our aim with the new enclosure was to isolate the temperature sensor more.
Very tight fitting of the PCB inside the enclosure
Sometimes it was quite difficult to get the PCB into the enclosure because you had to exactly hit the PCB holders on the opposite side. Often this took quite long and was frustrating. Also, sometimes with the OLED display mounted, it was very tight to push the PCB into the enclosure.
So we wanted a much easier to assemble enclosure.
Fixation of the PMS sensor
Although we provide screw holes on the PCB to mount the PM sensor, most people used double sided tape. However tape does not last forever and from time to time the PM sensor becomes loose.
So in the redesigned enclosure we wanted to make sure that the PM sensor cannot move around.
We provided a separate wall mount that clipped into the vents of the sensor but made the sensor look much bigger so we wanted to integrate the wall mount with the new version.
Development of our new enclosure
When we developed the enclosure for our commercial sensor AirGradient One, we worked together with Rico Jay Beringuela. He is a very experienced engineer in 3D modelling especially on plastic injection mold design and simulations, product technical 2d drawings and rendering. We were extremely happy with his work and thus asked him if he would like to support our open hardware and are delighted that he immediately agreed to volunteer and develop a professional design for our new enclosure.
We did the following modifications:
- Snap design with a top and bottom cover
- Integrated wall mount holes
- Snap design so that you do not need screws
- Fixation of the PMS sensor
- Optionally a clip-on temperature probe enclosure that can house the SHT30 and isolate it from the internal heat of the main enclosure
The new design looks like this with the optional clip-on temperature probe for more accurate readings:
We are also having a version with the cutout for the optional OLED display.
I am sure you will like this new enclosure and once again a big thank you to Rico for supporting this project. In case you want to work with Rico, you can reach him under firstname.lastname@example.org or WhatsApp +639368830540.