Housing

The housing for the BEVO Beacon was cut from 1/4-inch plywood using a precision laser cutter. The original version of the device consisted of 7 pieces shown in the figure below. Inside the device, there are two main compartments separated by a middle partition: a sensor compartment and a Raspberry Pi (RPi) compartment. Four sensors (CO2, CO, NO2, and PM) are contained in the sensor compartment while the two others (TVOC and light) are mounted to the top of the sensor compartment. The RPi, printed circuit board, fan, OLED screen, and real-time clock are all contained in the RPi compartment.

Individual Panels

Each of the Panels is described in more detail below:

• Panel (a): one of the small end-panels with multiple hexagon cuts to allow air flow
• Panel (b): the other small end-panel with pre-drilled holes to mount the carbon dioxide sensor and a small rectangular cutout to expose the sensor to nearby air
• Panel (c): one of the long side-panels. The cooling fan mounts directly to this panel and pulls air through the more central IEL logo. The rectangular cut in Panel (c) allows researchers to feed power and HDMI cables into the device and connect to the RPi.
• Panel (d) the bottom which contains four pre-drilled holes to mount the RPi and two rectangular cutouts which fit the partition panel.
• Panel (e): the other long side-panel that contains cutouts for the sensor heads on the carbon monoxide and nitrogen dioxide sensors allowing them to sit flush with the outside of the device.
• Panel (f): the top which contains two filed rectangular areas which allow the light and total volatile organic compound sensors to sit flush with the housing. A rectangular hole is cut directly beneath the filed area for the light sensor so the header pins are accessible from inside the device. Another small rectangular hole is cut to the right of the area for the total volatile organic compound sensor so that the connection wires can feed into the device. One other rectangular hole is cut below the filed areas which fits the partition panel, keeping it in place. The OLED screen is also mounted to the bottom of this panel with the readout visible through one of the larger hexagonal cutouts -- location of the OLED screen varies from device to device.
• Panel (g): the middle partition which contains a smaller cutout at the top for wires to feed from the sensor compartment to the RPi compartment. The larger rectangular area makes the USB ports on the RPi 3B+ accessible by the sensor compartment so that we can connect the carbon monoxide and nitrogen dioxide sensors.