Tag: Wemos D1 mini

After months of exposure to Shivajinagar’s traffic and running on a 12V fan 24×7 (or whenever the mood was not bad), here’s the dust settlement on the original version’s innards.

So it proves that this design is bad at the fundamental level. This amount of dust, and expected condensation will definitely cause some shorting someday. The newest design Breathe2 V1.2 bypasses this condition by shielding the external environment from the components. Only the underside of the PCB (where there are no components except a LED) is exposed.

The new Breathe2 V1.2 version is ready. Soon we will have 6 of these at various places in Pune.

They are enclosed in such a PVC container:

V1.1 was designed to fit into a cap of a PVC pipe and all this held upside down so that the cap is on top. The gaps in the PCB would allow the air sensor to get fresh air and so on. The PCB would have a dual task as a PCB and of keeping the components mounted on it from being exposed to external weather conditions.

However, the biggest mistake (Subir’s) was the selection of the power supplies MP1584 (see the 5V written by hand on the left disc) which ran hot within a few minutes leading to resetting of the boards.

10 PCBs were made, some were populated, but due to the fundamental problem of power supply, all this had to be scrapped.

Inspired by Breathe device network of IndiaSpend.com

Aim:

Make a low cost but decent performance air quality monitoring device that can upload real-time data to the web for city-scale geographic analysis of air pollution.

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Breathe2 Features:

• Bosch’s BME280 sensor : pressure, temperature and Relative Humidity
• Sensiron’s SPS30 sensor: PM1, PM2.5, PM4, PM10
• Wemos D1 mini Lite : ESP8266 based microcontroller with WiFi.
• SIM800L : GSM/GPRS module for cell tower connectivity (alternative to WiFi)
• Simple low cost physical structure of PVC pipes.
• Opensource (link soon).

 

Where is it installed:

For testing and calibration purposes Prototype1 has been installed about 10m away from the government’s SAFAR device situated at Indian Meteorological Department (IMD) Office (Shimla Office as known in Pune) at Shivajinagar, Pune.

Live data:

• Pressure, humidity and temperature : https://thingspeak.com/channels/795358
• PM mass concentrations : https://thingspeak.com/channels/795359
• PM number concentrations : https://thingspeak.com/channels/795363

 

Physical structure overview

Challenges / next steps:

• Verify if Particulate Matter (PM) data is similar to SAFAR data from Govt. of India.
• See if device can withstand harsh external conditions such as thunderstorms, heat waves and dew condensation conditions.
• See if device has repeatability over various environmental conditions.
• Develop robust web-services for collection, analysis and public display of data.
• Dream: Add a noise sensor to device.

 

Team:

1. Abhijeet Savant
2. Subir Bhaduri
3. Mayuresh Kulkarni