6 ms·
If you want to DIY it, Aranet4 uses a Senseair Sunrise which can be had for 1/4 of the price on Digikey [0]. Senseair has Arduino samples on GitHub [1]. I pers
by fotta 4y ago
If you want to DIY it, Aranet4 uses a Senseair Sunrise which can be had for 1/4 of the price on Digikey [0]. Senseair has Arduino samples on GitHub [1].
I personally have an SCD30 monitor which claims the same accuracy and like it. The important thing is to calibrate them in outside air to 400ppm.
[0] https://www.digikey.com/en/products/detail/senseair/006-0-0007/13981683 https://www.digikey.com/en/products/detail/senseair/006-0-00...
[1] https://github.com/Senseair-AB/Sunrise-Examples---Arduino https://github.com/Senseair-AB/Sunrise-Examples---Arduino
- sleepytimetea 4y agoThank you...$250 sounds excessive. I can hook up an OLED screen and ESP32 to the senseair and get the same ? I could even send levels to my home IOT InfluxDB for historical charting.
- fotta 4y agoYep. I do the exact same thing with my SCD30 and an ESP32 with HomeSpan to bridge it to HomeKit.
- dathinab 4y agoyou can do so, and properly calibrate it, and cross check it with some "known good" sensor you lend yourself from a friend and make sure you get the heat sensitivity of sensor and stuff like that right etc. most people can't, or more precise they probably can put something together but can't make sure it works correctly under any situation (in operation range) what you pay for is that someone makes sure it works properly else you can get sensors with similar or same hardware on amazon too, it's just that their correct reliability is not guaranteed at all and just checking if the values outside seem right is by far not enough to verify that (because it e.g. might behave right on low but not high CO2 levels or not on high/low humidity, etc.)
- Youden 4y agoYou generally don't have to go to all that effort unless you want extreme accuracy. For "Good enough", you buy the sensor, follow the application notes and instructions from the manufacturer, calibrate it in fresh outdoor air and you're good to go.
- dathinab 4y agothe problem is it's often not good enough I have seen tests with sensing devices which seemingly where good outside but then e.g. scaled wrongly being way of at higher CO2 levels (either way higher or way lower).
- Youden 4y agoI haven't seen that and I've deployed nearly 100 sensors. Perhaps you've left the auto calibration on? That's usually a recipe for disaster (and one that can be avoided by reading the datasheet).
- wkat4242 4y agoThese sensors all auto calibrate, you just have to expose them to outside air once a week. This includes all the sensors integrated in these off the shelf products like the author is using, which could explain the extremely high readings.
- vinaypai 4y agoThe device sounds like it was designed to separate the gullible from their money, so the price point was well optimized for that.
- icedchai 4y agoI'm going to check this out! I have a spare Arduino and sounds like a good application.
- chris_va 4y ago> 400ppm The outside ppm changes quite a bit in cities. CO2 dome effects can push it 2x higher.
- someonewhocar3s 4y ago[dead]
- kolinko 4y agoCan you provide a citation? I live in a city center Warsaw, and co2 outside is similar to anywhere else - around 420-450 max at all times. Perhaps it's due to a good city design with multiple open spaces though.
- 323 4y agoCO2 concentration seems to depend on actual location: https://www.researchgate.net/figure/The-maps-of-global-historical-atmospheric-CO2-concentrations-ppm-averaged-during_fig2_359162493 https://www.researchgate.net/figure/The-maps-of-global-histo...
- kolinko 4y agoThis paper show differences of ~10% across the globe. Doesn't say anything about co2 concentrations being 2x higher in the cities.
- chris_va 4y ago(Actual readings from Seattle, as an example) https://www.pmel.noaa.gov/co2/story/Space+Needle https://www.pmel.noaa.gov/co2/story/Space+Needle Older study https://www.sciencedirect.com/science/article/abs/pii/S135223100000412X https://www.sciencedirect.com/science/article/abs/pii/S13522... ... tldr a higher planetary boundary layer over cities can form under various weather conditions. That reduces mixing, and cities are large sources of CO2.
- 4y ago
- ultrarunner 4y agoThanks for this! I very much do want to DIY it, but lacking the time and my 9-year-old looking for a circuit python project, this might just fit the bill.
- ahaucnx 4y agoWe maintain a popular open hardware air quality monitor that also uses a Senseair CO2 Sensor [1]. This gives you a lot of flexibility on how to use the data. The pre-soldered version is easy to build and also includes a PM sensor. [1] https://www.airgradient.com/open-airgradient/kits/ https://www.airgradient.com/open-airgradient/kits/
- FloatArtifact 4y agoLooks like you don't sell the pro boards by themselves without the inclosure.
- ahaucnx 4y agoNo, but the Gerber files are available on our instructions page. So far people that were interested in the combination of enclosure and pcb or the whole kit.
- FloatArtifact 4y agoPricing out the parts buying third party and there's very little savings in doing so due to the cost of enclosure and the pbc especially the additional 24 to $30 shipping.
- CommanderData 4y agoI'm wanting a Co2 monitor that works without cloud and looked at some of the sensors available. Does the sensor in your project need to be taken outside to calibrate? I stopped when I realised many sensors (like scd30/40) need this making it very impractical.. Has to be done once while powered on the whole time in a 7 day period.
- ahaucnx 4y agoI think pretty much all indoor air quality monitors with NDIR sensors have by default an automatic baseline calibration. Our kicks in every 7 days. So you should somehow reach ambient CO2 levels once a week to have it properly calibrated.
- 4y ago
- mxmlnkn 4y agoAny thoughts on the Sensirion SCD41? It is almost half the price. https://sensirion.com/products/catalog/SCD41/ https://sensirion.com/products/catalog/SCD41/ https://www.digikey.com/en/products/detail/sensirion-ag/SCD41-D-R2/13684005 https://www.digikey.com/en/products/detail/sensirion-ag/SCD4...
- Youden 4y agoThe SCD41 is a very different sensor. The Senseair Sunrise requires through-hole assembly, uses a low-power version of NDIR and is relatively bulky. The SCD41 requires surface mount assembly, uses a higher-power proprietary technology based on MEMS and is very compact for a CO2 sensor. Personally I've been very happy with Sensirion's sensors and I've played with the SCD41 quite a bit. The trouble with it for hobbyists is the assembly. It has what seems to me to be pretty picky requirements for soldering. I've attempted to do it myself but I keep managing to pop off the metal covering. Haven't tried the Senseair Sunrise but such low power requirements are very very appealing because they mean the sensor can be battery-powered. The SCD41 isn't bad but powering it for a year means a lot more batteries. With a 1 min sampling period, the SCD41 uses 1.5mA while the Sunrise uses 21µA.
- joshvm 4y agoI've used these before from Amphenol/Telaire: https://www.amphenol-sensors.com/en/telaire/co2/525-co2-sensor-modules/3215-t6700 https://www.amphenol-sensors.com/en/telaire/co2/525-co2-sens... I think they're around 60 bucks (e.g. the T6793) so they aren't the cheapest around, but they're good quality. They have a normal header you can solder a few wires into. Probably the best approach for the Sensirion sensor is to oversize the pads a bit and use paste to re-flow underneath.
- Youden 4y agoI have quite a few of the older T6613/T6615 sensors that I got when Newark was selling them for like $10 a piece. The way I soldered the SCD41 is with a pre-made PCB footprint, some solder paste and a mini PCB heater. I think the problem was too high heat. I need to try it again with low-temperature solder paste. But for my application the Senseair Sunrise looks a lot better.
- belorn 4y agoHow accurate is it in term of linearity of calibration, and how much does it drift over time? As a diver I use oxygen sensors, and those should be calibrated once every third day, and linearity can go bad from everything between 6 months to a few years. If I went with a DIY solution i would definitively go with 3 sensors so one can at least use voting to determine which sensors to trust, and to measure relative drift.
- OisinMoran 4y agoOut of curiosity what voting mechanism would you use? Obviously consensus would be solid for something binary but for a ~continuous value like CO2 level I'm not sure what would make the most sense.
- belorn 4y agoOne method used in one of my diving equipment is to take one sensor and compare the value to the average to the other sensors, and if it's too far out, mark it as potentially broken. Cycle to next one and repeat. This can still situation where either a bad sensor is marked as good, or a good sensor marked as bad, so a human operator is still required to monitor the decisions made.
- iudqnolq 4y agoThw Aranet4 comes with instructions never to recalibrare unless you have a controlled environment as good as their factory setup, fyi.
- fotta 4y agoThe SCD30 I have quotes a drift of +-50 ppm over its lifetime. https://sensirion.com/media/documents/4EAF6AF8/61652C3C/Sensirion_CO2_Sensors_SCD30_Datasheet.pdf https://sensirion.com/media/documents/4EAF6AF8/61652C3C/Sens...