Show HN: I made a CO2 sensing Christmas ball

github.com

12 pointsJJensen13 comments

Good one! One thing that never sat right with me about CO2 sensors is that apparently they drift considerably, and automatically calibrate themselves relying on being exposed to 400 ppm on a regular basis, otherwise they might have lower readings than the real amount. Did you find it's easy to achieve that in a house, or do you need to be very deliberate about ventilation or periodically bringing the sensor outside?

Thanks for your question, geeB! I have not tested the accuracy of the readings from the sensor, but after searching the web I found that the easiest solution would be to bring it outside once in a while. The other solutions would require a sensor that is calibrated or a room with a known value of CO2.

Maybe it is better to create a christmas star for the window (If we have to keep the christmas vibe)? Then it would be able to recalibrate because it is frequently being exposed to 400 ppm? I will do some tests in my working environment to see how big of a problem the recalibration is.

You could also consider to decouple the sensor from the Christmas ornament an broadcast the values over BLE or WiFi. That way you could place the sensor in the window without rethinking the rest. I think the greatest disadvantage would be that you have to relocate the sensor with the ornament.

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