4 ms·

What sensor are you using? Just curious.

tpmx 5y ago
For DIY, there was a pretty good discussion on suitable sensors in the AirGradient post from three months ago that Jeff linked to: https://news.ycombinator.com/item?id=27125060 https://news.ycombinator.com/item?id=27125060 tl;dr: seems like you want an NDIR sensor (https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor). Some options, with digikey @1 prices: Senseair S8 (Sweden): $48 Sensirion SCD30 (Switzerland): $63 Amphenol Telaire T6713 (US): $96 If I were to buy an expensive black box iot solution, I'd at least verify that it had an NDIR sensor.
- s0rce 5y ago
  I'm using an SCD41 with an OLED+microcontroller (using Sensirion's example code hacked a bit) and it seems to work well, cheaper than the NDIR using some photoacoustic magic.
  - tpmx 5y ago
    $37 @1, but not in stock at digikey, and an 11 week lead time. It's pretty tiny... I wonder if/when it will be possible to put a high quality co2 sensor in an IP68 iPhone...
    - s0rce 5y ago
      I had purchased the dev kit sek-scd41 but its out of stock as well. The SCD41 also does RH and T so you don't need a separate sensor for that.
macNchz 5y ago
I'm using an Awair Element, I didn't do a ton of research on alternatives, but the app is pretty good and it "just works".
- newfonewhodis 5y ago
  I've been thinking of getting it what are your thoughts on longevity of it? Will it last at least a few years? I also see in some Amazon reviews that measurements get "stuck" to some extreme. Have you noticed that too?
  - richardfontana 5y ago
    I've had an Awair Element for about 16 months. The only time I've experienced what you may mean by "stuck" measurements was about a month ago, when PM2.5 was puzzlingly and worryingly at a consistently higher than usual level for a couple of days. Trial and error eventually suggested that there was a piece of dust stuck in the sensor or something like that. Upon blowing on the sensor, the measurement returned to normal.
  - macNchz 5y ago
    After a year I don’t see any issues with it, the sensors don’t seem to have drifted or changed in their responsiveness at all. It has crashed once or twice and stopped responding but was fine after a power cycle. With any IoT device I’m wary about longevity re app support, I can’t say how long Awair will support this device or whether they’ll provide access to it after they stop, but I’m less concerned for a device like this vs, say, a major appliance.
- tclancy 5y ago
  Like you, and for the same reasons, I recently bought an Awair. At the risk of a derail, one thing I have been thinking about ever since: when I played D&D as a kid, they said the difference between Intelligence and Wisdom was, "Intelligence is knowing that it's raining, Wisdom is knowing to go inside." How much of these things are adding to our intelligence without adding to our wisdom? I am now constantly aware of particulates and everything else it cares to send me alerts about (which I will soon shut off) but how much better off am I once I established my air quality is basically Very Good. The problem with all this "intelligence" is the Internet is very good at showing you search results for what you want to see, so Googling "Should I be worried about fine particulates" is a search destined to turn your anxiety into a full-blown panic attack. No idea what the answer is, and I am impressed with the level of effort that went into the Awair app, but it would be nice to have more reasonable context in all IoT devices. Yeah, I know.
karmelapple 5y ago
To add to the list of sensors: I was most curious in CO2 levels, so I got an Aranet4: https://www.amazon.com/dp/B07YY7BH2W/ref=cm_sw_r_cp_api_glt_fabc_68MQ94BWJ2CT0JFTMCGV https://www.amazon.com/dp/B07YY7BH2W/ref=cm_sw_r_cp_api_glt_... It’s got an eink screen, and I haven’t had to recharge it since I got it 8 months ago. I really like it.
- Robotbeat 5y ago
  Are there any affordable CO2 sensors that don’t use outside air for calibration of ppm? I want to know how outside air CO2 levels change as well. Would be interesting to see day to day changes and how big they are in absolute terms. (Also to show people about how CO2 levels are changing globally… without just pointing to a website of someone else’s measurements.)

tpmx 5y ago

For DIY, there was a pretty good discussion on suitable sensors in the AirGradient post from three months ago that Jeff linked to: https://news.ycombinator.com/item?id=27125060 https://news.ycombinator.com/item?id=27125060 tl;dr: seems like you want an NDIR sensor (https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor). Some options, with digikey @1 prices: Senseair S8 (Sweden): $48 Sensirion SCD30 (Switzerland): $63 Amphenol Telaire T6713 (US): $96 If I were to buy an expensive black box iot solution, I'd at least verify that it had an NDIR sensor.

s0rce 5y ago
I'm using an SCD41 with an OLED+microcontroller (using Sensirion's example code hacked a bit) and it seems to work well, cheaper than the NDIR using some photoacoustic magic.
- tpmx 5y ago
  $37 @1, but not in stock at digikey, and an 11 week lead time. It's pretty tiny... I wonder if/when it will be possible to put a high quality co2 sensor in an IP68 iPhone...
  - s0rce 5y ago
    I had purchased the dev kit sek-scd41 but its out of stock as well. The SCD41 also does RH and T so you don't need a separate sensor for that.

macNchz 5y ago

I'm using an Awair Element, I didn't do a ton of research on alternatives, but the app is pretty good and it "just works".

newfonewhodis 5y ago
I've been thinking of getting it what are your thoughts on longevity of it? Will it last at least a few years? I also see in some Amazon reviews that measurements get "stuck" to some extreme. Have you noticed that too?
- richardfontana 5y ago
  I've had an Awair Element for about 16 months. The only time I've experienced what you may mean by "stuck" measurements was about a month ago, when PM2.5 was puzzlingly and worryingly at a consistently higher than usual level for a couple of days. Trial and error eventually suggested that there was a piece of dust stuck in the sensor or something like that. Upon blowing on the sensor, the measurement returned to normal.
- macNchz 5y ago
  After a year I don’t see any issues with it, the sensors don’t seem to have drifted or changed in their responsiveness at all. It has crashed once or twice and stopped responding but was fine after a power cycle. With any IoT device I’m wary about longevity re app support, I can’t say how long Awair will support this device or whether they’ll provide access to it after they stop, but I’m less concerned for a device like this vs, say, a major appliance.
tclancy 5y ago
Like you, and for the same reasons, I recently bought an Awair. At the risk of a derail, one thing I have been thinking about ever since: when I played D&D as a kid, they said the difference between Intelligence and Wisdom was, "Intelligence is knowing that it's raining, Wisdom is knowing to go inside." How much of these things are adding to our intelligence without adding to our wisdom? I am now constantly aware of particulates and everything else it cares to send me alerts about (which I will soon shut off) but how much better off am I once I established my air quality is basically Very Good. The problem with all this "intelligence" is the Internet is very good at showing you search results for what you want to see, so Googling "Should I be worried about fine particulates" is a search destined to turn your anxiety into a full-blown panic attack. No idea what the answer is, and I am impressed with the level of effort that went into the Awair app, but it would be nice to have more reasonable context in all IoT devices. Yeah, I know.

karmelapple 5y ago

To add to the list of sensors: I was most curious in CO2 levels, so I got an Aranet4: https://www.amazon.com/dp/B07YY7BH2W/ref=cm_sw_r_cp_api_glt_fabc_68MQ94BWJ2CT0JFTMCGV https://www.amazon.com/dp/B07YY7BH2W/ref=cm_sw_r_cp_api_glt_... It’s got an eink screen, and I haven’t had to recharge it since I got it 8 months ago. I really like it.

Robotbeat 5y ago
Are there any affordable CO2 sensors that don’t use outside air for calibration of ppm? I want to know how outside air CO2 levels change as well. Would be interesting to see day to day changes and how big they are in absolute terms. (Also to show people about how CO2 levels are changing globally… without just pointing to a website of someone else’s measurements.)