4 ms·

More concerning - can anyone explain why there is such a variation in the results from the DC powered unit vs. the TENG-powered one? The graph at the bottom of

by dfex 1y ago

More concerning - can anyone explain why there is such a variation in the results from the DC powered unit vs. the TENG-powered one? The graph at the bottom of the report shows a difference of 30-50ppm between both units when they are sitting side by side on the bench.

zipping1549 1y ago
I skimmed the original article and it only mentions the graph and says that it's "comparable to DC powered unit". I'm guessing < 100ppm difference is somewhat acceptable?
- dfex 1y ago
  You might be right - it's just odd that it's always showing "more" rather than similar amounts. Also, according to Claude[1] a 50ppm difference is equivalent to around 25 years current atmospheric carbon increase. * Pre-industrial (1700s): ~280 ppm * 1958 (when systematic measurements began): ~315 ppm * 2000: ~370 ppm * 2015: ~400 ppm (milestone crossed) * Current: ~420-425 ppm [1] "What is the normal range for background CO2 concentrations in the air?"
  - strogonoff 1y ago
    It’s crazy to think that many people alive today experienced a 30% increase in ambient atmospheric carbon dioxide concentration within their lifetimes.
  - devmor 1y ago
    You’re missing some deeply important context there, which is that those measurements are for outdoor atmospheric CO2 only. Average indoor air quality ranges from 400-1000 ppm CO2, with adverse mental effects starting to appear close to 2000 ppm. In that context, you can see why a 50 ppm difference is marginal. This is why asking an LLM is not generally a great idea for understanding something - you need to follow it up with more research.
    - jobs_throwaway 1y ago
      > adverse mental effects starting to appear close to 2000 ppm. cognition is harmed starting at 1000ppm (https://pmc.ncbi.nlm.nih.gov/articles/PMC3548274/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3548274/)
      - devmor 1y ago
        I'm having a hard time parsing the data in this paper - is it showing that task focus increases at 1000ppm compared to 600ppm CO2 exposure?
  - freeone3000 1y ago
    Not odd at all that it’s always showing more — sensor error is often biased. This is within the listed range though.
  - officeplant 1y ago
    I have to know, what's the the rise of people like you chiming in with AI sourced tidbits? It's like the people with no knowledge on a subject that use google as a quick catch up tool so they can participate in a conversation, but somehow even worse. Are they the same people, but now lazier or just true believers in the non-sense engines?
callmemclovin 1y ago
That's in the normal range of accuracy of modern CO2 sensors, for example SCD40 from Sensirion is described with an accuracy of ±50.0 ppm ±5.0 %m.v.
- jtrueb 1y ago
  That’s if the voltage supply was stable and within electrical specs for a sufficient period of time. We can see this is a snippet 2 hours into the discontinous collection. 3.6V is the maximum value that the nrf52832 SoC can handle. I would suspect the VDD is variable.
- ahaucnx 1y ago
  Actually the real accuracy is much better, especially with optical NDIR sensors. We do a lot of testing against reference grade sensors and typically see very good performance and reproducibility [1]. [1] https://www.airgradient.com/blog/performance-of-low-cost-co2-sensors-outdoors/ https://www.airgradient.com/blog/performance-of-low-cost-co2...

by dfex 1y ago

zipping1549 1y ago

I skimmed the original article and it only mentions the graph and says that it's "comparable to DC powered unit". I'm guessing < 100ppm difference is somewhat acceptable?

dfex 1y ago
You might be right - it's just odd that it's always showing "more" rather than similar amounts. Also, according to Claude[1] a 50ppm difference is equivalent to around 25 years current atmospheric carbon increase. * Pre-industrial (1700s): ~280 ppm * 1958 (when systematic measurements began): ~315 ppm * 2000: ~370 ppm * 2015: ~400 ppm (milestone crossed) * Current: ~420-425 ppm [1] "What is the normal range for background CO2 concentrations in the air?"
- strogonoff 1y ago
  It’s crazy to think that many people alive today experienced a 30% increase in ambient atmospheric carbon dioxide concentration within their lifetimes.
- devmor 1y ago
  You’re missing some deeply important context there, which is that those measurements are for outdoor atmospheric CO2 only. Average indoor air quality ranges from 400-1000 ppm CO2, with adverse mental effects starting to appear close to 2000 ppm. In that context, you can see why a 50 ppm difference is marginal. This is why asking an LLM is not generally a great idea for understanding something - you need to follow it up with more research.
  - jobs_throwaway 1y ago
    > adverse mental effects starting to appear close to 2000 ppm. cognition is harmed starting at 1000ppm (https://pmc.ncbi.nlm.nih.gov/articles/PMC3548274/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3548274/)
    - devmor 1y ago
      I'm having a hard time parsing the data in this paper - is it showing that task focus increases at 1000ppm compared to 600ppm CO2 exposure?
- freeone3000 1y ago
  Not odd at all that it’s always showing more — sensor error is often biased. This is within the listed range though.
- officeplant 1y ago
  I have to know, what's the the rise of people like you chiming in with AI sourced tidbits? It's like the people with no knowledge on a subject that use google as a quick catch up tool so they can participate in a conversation, but somehow even worse. Are they the same people, but now lazier or just true believers in the non-sense engines?

callmemclovin 1y ago

That's in the normal range of accuracy of modern CO2 sensors, for example SCD40 from Sensirion is described with an accuracy of ±50.0 ppm ±5.0 %m.v.

jtrueb 1y ago
That’s if the voltage supply was stable and within electrical specs for a sufficient period of time. We can see this is a snippet 2 hours into the discontinous collection. 3.6V is the maximum value that the nrf52832 SoC can handle. I would suspect the VDD is variable.
ahaucnx 1y ago
Actually the real accuracy is much better, especially with optical NDIR sensors. We do a lot of testing against reference grade sensors and typically see very good performance and reproducibility [1]. [1] https://www.airgradient.com/blog/performance-of-low-cost-co2-sensors-outdoors/ https://www.airgradient.com/blog/performance-of-low-cost-co2...