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Comment by homebrewer | Hacker News Reader

JFYI: a (hopefully much) cheaper stripped down version of the device would be useful. Air quality is the worst in poorer regions of the world, and as someone who suffers from horrible air pollution, but who's also living a relatively cushy life (by our standards), I can assure you that $200+ for an air quality sensor puts it into the "unobtainable" bucket. Add shipping and it probably gets closer to $300, which is roughly equal to the median monthly salary over here.

Your NO₂ measurements make it a really interesting device compared to most alternatives that only measure particulate matter. All gas sensors that are theoretically possible for me to obtain cost hundreds of dollars by themselves.

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I'm a big fan of the AirGradient. They used to have really cheap DIY kits available: either $19 for the PCB + enclosure alone (with the assumption you already have the other parts or will buy them off aliexpress) or $96 for everything. Looks like the current kit is $138. If that's too much, you might be able to make it cheaper by downloading the KiCad and STL files off their website [1], getting PCBs printed elsewhere, 3D printing the case, and sourcing the rest of the parts from aliexpress. When you do it that way, you can also omit any sensors that are not of interest to save money, and perhaps add them in later.

[1] https://www.airgradient.com/documentation/overview/

Ya, my AirGradient ONE is $200 and has been one of the best investments in my home. Using it, I discovered how the drying polyester clothes wrecks the indoor air quality and how not to burn baking oils by controlling temps better.

Drying polyester clothes releases CO2 to unhealthy levels?

Probably referring to particulate matter. The AirGradient measures PM2.5. I happen to have an air purifier near my W/D and it catches a lot of lint in the prefilter.

I've been having problems with my devices, though. The reliability sucks, they lock up all the time.

Additionally, the OLED screen needs to shut down in the dark. I added a VEML lithgt sensor to my devices for that.

The light strip they added to the new devices is fun. You get a free nightlight too.

Interesting. I have been running three of their devices of different generations in my house for several years now with no hangs.

No idea why. I tried to change the power supply, and even slightly overvolt the power (to 6V from nominal 5V).

I haven't had any issues with lock-ups.

The LEDs and screens can be adjusted (or turned off) on a schedule with the latest firmware.

I have one that uses these sensors though I made a variation of this in a different layout and with a different power system (usb c and one that is powered off 12v). Wonder if JLPCB is affected by tariffs. I’d love to do a new board.

I'll preface this by saying that product design and manufacturing and public-proofing is long, hard work, and the retail price of this product is likely to be well justified for all kinds of reasons.

That said, looking at the main active components that are listed, we have -

ESP32S3 IC : $4 retail, SCD41 Sensor : $21 retail, SGP41 Sensor : $8 retail, LPS22 Sensor : $4 retail

Which is very hopeful, in the sense that some key functionality of this kind of device could potentially be open sourced and pared back to a minimal cost where hobbyists could build versions suitable for the economics of developing countries.

Tariffs are having a big impact on people outside the US using CrowdSupply.

CrowdSupply ships everything via Mouser US - so if you are outside of the US you need to export your products to Mouser. That hits you with tariffs and the tariffs are charged on what CrowdSupply are paying you for the products.

If the majority of your product is manufactured in China (e.g. PCBA) then it's very likely that the COO for your product will be China. So, you will get stung with whatever crazy tariffs are currently in place.

This has been very tricky to navigate for us. We almost launched the campaign right before the Tariffs got announced. Luckily, we had the opportunity to wait it out. While CrowdSupply is an awesome platform, and I would use it again, the requirement to export everything to the US is a problem in such situations.

Yep, it's bitten me - just about to ship my boxes off. I'll still probably break even fortunately (or at least not lose a massive amount of money).

Uff, that's hard! I'm sorry to hear that. What projects is yours?

ESP32 Rainbow - https://www.crowdsupply.com/atomic14/esp32-rainbow

I'm seeing if I can argue for a UK country of origin. But also, I want to get the boxes shipped and out to people - so think I'll just swallow it.

> ESP32S3 IC : $4 retail, SCD41 Sensor : $21 retail, SGP41 Sensor : $8 retail, LPS22 Sensor : $4 retail

I am not an expert but if I get these components, how easy would it be to build a hacked version out of these?

I’m not in the US and unaffected by the tarrifs.

Hardware companies design breakout boards for most semi popular sensors (including the SCD41 and the SGP41) so arguably if you can put things together on a breadboard and can setup I²C comms (for example with an Arduino library) then it is certainly accessible to a hobbyist.

Pretty simple. You can find lots of examples of getting each sensor working by googling "site:github.com ESP32 SCD41" etc.

There are libraries which make it extra-easy:

SCD41: SparkFun_SCD4x_Arduino_Library.h

SGP41: SensirionI2CSgp41.h

LPS22: Adafruit_LPS2X.h

Take a look through the past HN discussions of this and similar air quality monitors. Can also search HN for chip names themselves (like 'SCD41'). Many people note that the sensors drift over time, and buying "calibration bottles" of low-concentration CO2 is a slight hurdle for many - they're not that crazy expensive, but they're expensive enough to be a bit of a block for some.

Sounds great!

I’ll give it a try and see how far I go. Do you know any discord channels where such folks hang out?

P.S. Apt username BTW.

Super easy, use esphome. There's a few vendors out there that sell pre built devices, and they usually make their configs available if you want to DIY it. For example Apollo automation.

The basic connections are easy in theory, especially if you get a ready-to-use, breakout-board version (e.g. Adafruit modules) of each, for perhaps double or triple the price. Then it's just a matter of wiring each sensor to data lines of the controller chip, and giving everything the power it requires.

Programming libraries contain the basic functions necessary to access to sensors' readings with simple lines of code.

But the devil is in the details - to go from that to an actual practical, working model and physical build is quite a lot of work. Expect months, in hobbyist terms.

Thanks for the feedback that I can totally understand! We hoped to offer the product at a lower price, but as I mentioned in other replies, it's hard to be competitive when planning for small quantities. That said, I can totally see us offering a simplified and cheaper version in the future that is affordable to more people.

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