Maybe the circuit designer got his sensors all mixed up in a box and thought "the one that reacts when I blow on it must be the CO2 sensor" - too bad he wasn't entirely sober at that time... 😂
"Unless you live in a hermetically sealed building" our office moved to a whole floor in a WeWork a few years back, and it always felt "stuffy" in winter. Towards late morning I was always fatigued and sleepy. I put it down to the coffee. Someone else bought an proper air quality meter and we realised that in winter, the CO2 levels in the 200-person office would rise from 9am through to about 2pm, and the moment they hit 5000ppm they would drop abruptly and hover at a lower level. This pattern repeated every day. It seemed that to save money on heating WeWork had configured the HVAC system to let CO2 rise up to the legal maximum before they let in outside air. Unfortunately, you start feeling drowsy and foggy around 2000ppm. Without the CO2 monitor, we would have blamed the coffee - because it would be crazy to suggest that a company was suffocating the workers to save on the heating bill.
"because it would be crazy to suggest that a company was suffocating the workers to save on the heating bill." I think the existence of an office episode with this exact plot, albeit one of the more 'realistic' plots says otherwise
I wouldn't blame the office immediately. They could have simply set the limit too high (legal maximum = recommendation) to let fresh air in. You just need one or two people who don't really know about the effects of high CO2 levels and simply see the heating bill. Also, there are very effective ventilation systems which conserve up to 98% of the heat. So there's really no economic reason to not ventilate the air - not even with only 85-90% heat conservation which is standard. Ventilation is way more effective than windows so it might be a good idea to propose such ventilation. Especially from an economic standpoint more efficient workers are better for the company.
Nono it's COMPLETELY on par for companies to suffocate workers these days to save on heating. Especially where i live where costs went up 500% recently for large companies. Absolute insanity.
We have real CO2 sensors in our office building, with LED lights that go from green to yellow at 800 and to red at 1200 ppm. I designed and built them myself (around 150 sensors for the whole company) at the time we had all those mask and quarantine regulations. They contain the Sensirion SCD30 sensor module, which uses NDIR to detect CO2, which is accurate, but also quite expensive. They do help a lot with air quality monitoring, because as you mentioned, humans exhale CO2 at all times, and if too many humans are in one room with bad ventilation, the levels rise quickly. It will never reach dangerous levels in a normal building, but at 1500ppm and above CO2 causes headaches and reduces focus, which is usually a bad thing in work environments. High CO2 levels also mean a lot of exhaled air and therefore higher risk of aerosols (virus transmission), so respiratory infections have declined since we use the sensors and therefore ventilate the rooms when needed.
I bought one for my home last month. It is really good for disciplining me to regularly open the windows to vent in fresh air when it turns yellow. And it's been doing wonders to my general wellbeing so far.
We also have them at work, also introduced during COVID for the same reason. Some of them in the workshops are linked to extraction systems and will turn on the extractor if the value goes high.
In the UK, there was a move by a lot of amateur choirs to use such sensors as a way of getting back to rehearsing in person after the Covid lockdowns. Someone thought that choirs were a prime source of virus spread, and government took that view to heart, so choirs had to observe prohibition and then physical separation and masks far longer than most other groups. When the rules were relaxed, I bought a sensor from Amazon for around £40 - it looked somewhat like the one you took apart. It quickly became obvious that it was of no use as it sat there the whole evening of a rehearsal at around 420 ppm with very little variation. Now I see why. We didn't have a bar open, so we couldn't test it for alcohol. I'm glad to say that someone found out a much better technology and we used a sensor of that second type for a long time to check the air quality. I still use one in my bedroom - as someone said, it's good as a reminder of when to open a window.
A couple of years ago I parked in a parking garage that had CO2 sensors on the walls. I don't recall who made them but I looked them up and they cost a couple hundred dollars each. I'm pretty sure that they were wired to control the ventilation fans, probably an energy-saving measure compared to just running the fans all the time.
I have used NDIR-based CO2 sensors (MH-Z14, MH-Z19) in an office setting, and it was quite interesting to note the average levels. After seeing the PPM levels in a meeting room zip past 2,000 ppm with about a dozen people inside for an hour, it made sense to me that one would start feeling drowsy and lose focus during such meetings. It's not just that they're tedious wastes of precious life minutes. A number of studies have been performed on the impact of CO2 levels on cognitive functions, which show that a rise from ~400 ppm to 800 ppm drastically reduces one's ability to perform even basic office tasks. It's like being sleep-deprived, or tipsy. Beyond 800 ppm it just plummets and by the time you hit 2,000 ppm, individuals will begin to get headaches, start feeling nauseous, etc. At around 5,000 ppm you'll have people literally passing out, with a number likely having puked up their guts before then. In the open plan office of this place levels got to 800 - 1,000, which was a good hint to crack open a window, which helped a lot. In that sense, CO2 sensors are an invaluable tool to keep track of air circulation in a building, and the build-up of stale air. The same project (BMaC: Building Management and Control) also got used for other purposes, such as keeping track of the number of cups of coffee drawn from the machines via their serial port, which provided an interesting comparison point for CO2 levels and coffee consumption :)
I followed the same rabbit hole, working in an environment (one most would expect to be as conducive to best practice as possible) we're levels were regularly 1000-1400. When I mentioned to the HSO the same research you refer to, it was dismissed as a waste of time. The fact people regularly got headaches and underperformed in this environment, never seemed to crossed their mind. Ah well, that's life, just glad to see someone else has made the same connections as me about CO2 levels.
There's "zp16" written on the board, which is a VOC air quality sensor. The empty place for "infrared module" would be for the actual infrared CO2 sensor.
@@macieksoft electrochemical ones very often measure carbohydrates/VOC and by proxy measure "CO2 equivalent". They are much cheaper though than infrared sensors and often found in cheap "CO2" sensors. Infrared sensors is what you want for properly and accurately measuring CO2 levels, but they cost a lot more: cheapest NDIR sensor I could fing is MH-Z19 and it costs 15-20$, while electrochemical one can be bought for less than a dollar BTW a lot of those infrared sensors actually use the same data protocol used in flashing firmware/debugging microcontrollers (UART), so there's probably a revision that uses NDIR sensor Upd: there's also apparently a newer sensor SCD40 which uses I2C instead of UART
This is why I built my own CO2 meter. I knew exactly what was in it and learned something new while doing it. It also logs the data which you can view on your phone.
Got two running in my grow tents on ESP32's, measuring CO2, temp and humidity, calculating VPD and adding humidity as needed, then serving the data as a webpage. The modules seem to work very well, maybe not super-accurate, but reliable.
There are "CO2" sensors available that in the fine print says they are "CO2e" or "eCO2" sensors. Which means that they are VOC sensors, and the VOC level is cleverly and most often incorrectly used to guesstimate a probable CO2 level, assuming human presence. Could that be the case here?
Wow, this is really intriguing, thank you for sharing your knowledge on the matter, it's crazy to think that this could just be a bad product by mistake.....
TVOC sensors often do claim to be able to estimate CO2 - the part on this board looks like either the genuine or a clone of the Sensirion SGP30 or SGP40.
Yeah its a voc sensor. I'm currently playing with an adafruit one connected to a pi-pico-w. It makes guesses based on VOC's. It was 18quid. The Co2 breakout board sensors are 54 to 81 quid a pop. (I have not checked the sensor device only prices but they tend to follow the i2c breakout board with a few other surface mount thingmibobs fairly closely.)
We were having weird headaches and just foggy feelings since moving into our new house. Someone mentioned checking CO2 levels since the house is pretty sealed up. Got a sensor and it showed over 3000ppm, we also have all natural gas appliances. After getting it below 800ppm, we can tell a huge difference.
This recent explosion of information about how dangerous gas stoves are makes me think what it must have been like when they realized how dangerous leaded gasoline and paint was. A "oh crap now what do we do" moment lol
@@NotBROLL our gas boiler vents crap out of the side of my house, and i often wonder what is it venting other than steam and how much comes back in through my open window
@@skeetsmcgrew3282 leaded paint and gasoline were always known to be dangerous. The claim was that low concentrations were "safe". FWIW the inventor of leaded gasoline nearly killed himself whilst developing the product (and did kill a few reseachers). Pure teraethylene lead is incredbly poisonous to the point that a single sniff can hospitalise you
"monochromatic display with coloured panels printed over the circular segments" That's pretty much the description of how Space Invaders machines first went from B&W to colour. A few strips of coloured gel over the screen. Sometimes not much moves on from the 1970s.
If you ever build a control panel or instrument panel which requires (or would benefit from) backlit graphics, you may find yourself doing the same. ;) But to find it in a consumer product? Oh hell no. O_O
My nor-tec weather station has the background (above the backlight) printed with a landscape photo, text and different colors for inside/outside display sections. The actual display itself just consists of black and white LCD segments (in different shapes) on top. I find this a nice way of making a stylish looking display, but with extremely low power consumption (and probably price) compared to using a real OLED or TFT. Especially as the display is rather large. It's a good device, with temperature/humidity/air-pressure sensor built-in, with a radio clock receiver (DCF77) and a 433MHz receiver for up to three wireless external temperature/humidity sensor modules, adjustable backlight and a capacitive snooze button (for the alarm). And you can use it with two 1.5V AA batteries and/or with an external 5V power adaptor. The "CO2"detector display looks similar, maybe the color is printed on the backlight diffusor, then the LCD just needs to block out the light.?
The Chameleon in-home display for my smart meter does this to give coloured segments, also oled displays I have bought have an option for a yellow strip of pixels on an otherwise blue display to highlight an info bar. This display is also used in an old Alba personal DAB radio I have, the yellow area is used for icons for signal strength, mode, battery state etc. Many AV separates have a monochrome fluorescent display where some icons such as record have coloured panels to change them from white to red or yellow.
CO2 is used as a proxy for measuring air that is stagnant. Mostly in the context of trying to ascertain if a public building has adequate exchange of outside air to help reduce airborne virus spread.
and the sensor is a VOC sensor that uses VOC as a proxy for CO2 in human presence. Meaning: This device guess air staleness by guessing CO2 Content by guessing VOC content. Why not skip the extra steps and guess air staleness from VOC content?
Our HVAC system at work has a CO2 sensor in it. If it gets above the set level it opens a damper to pull in fresh air from outside. It's pretty neat to look at the graphs in the reports it can generate and see the level around 425 ppm first thing in the morning and as everyone arrives it starts climbing. Usually just after noon or 1PM the level gets high enough that the damper starts cracking open and the CO2 levels off. If we have an event that brings an extra 100-200 people into the building it will spike way up and the damper goes wide open trying to compensate.
Clive, you were wondering why someone would want to measure Co2 content. We use an array of sensors (including Co2) when welding in a tank or bund. Co2 is heavier than air so you end up with the bottom of the tank filled with Co2 and you suffocate. Always good to have something beeping away in the background. Though obviously not this piece of crap.
Monitoring for air quality in lecture rooms and in our beer fermenting/storage/bottling facilities. It's a useful reminder for airing early to avoid fatigue.
I've got something similar at my work in the soda closet, people tend to leave hoses unhooked and the room tended to make people sleepy before they put the alarm in
@@v.sandrone4268 great idea but I think there's a flaw. Should we call it a fatal flaw? So much for an apprenticeship. They get one chance to learn the lesson.
WOW! I am speechless, literally: I thought to take that EXACT type of sensor (and - indeed - it was on my AliExpress Wishlist since a long time now): I was waiting before getting one exactly to understand how much them should be considered reliable and... really I have no words, except a huge *THANK YOU* for letting me save my money and search for something better I knew CO2 sensors were quite expensive and it sounded strange to me finding those devices as cheap as ten-ish euros each 🤯 now I know exactly why Sharing this video everywhere 💪
Wow! I just received a nearly identical unit in the mail last week! Mine’s the fancier version of this one that “detects” formaldehyde, TVOC, PM2.5, PM10, CO and CO2. But mine actually has a GP2Y10 (dust sensor) module in it. I’m doing a soda steam test right now, but from my first test it just detects alcohol. It only has one gas sensor in it, so it’s clearly lying about something. I’ll update this comment with an edit in a few minutes Edit: just put it in a bag of pure CO2 and the CO2 reading is dropping… Edit2: Whoa! Whatever sensor they’re using actually does detect CO2 but registers it as TVOC. Somehow in the bag of CO2, it mins the CO2 reading but maxes the TVOC reading. There’s something fancier going on here. I think the gas sensor is actually sensitive to two types of gases, but the math isn’t working properly. I just breathed 2x beer breath into the CO2 bag, and the CO2 reading started climbing. Man, I wish the gas sensor had a number on it. I think I might have to dremel it open and see if I get any clues.
@@pyromen321 if yours has "PG-L58" on a sticker on backside - we're on the same boat. i was thinking it's a scam, as they're quite glitxhy and prone to runaway (especially when on charger), and battery does 8 hrs MAX. now i'm pretty sure.
I Just took mine apart and it has a reasonably OK particle sensor and separate humidity and temperature sensors... but everything else is "faked" by some calculation from one tin oxide sensor of the hot can variety Edit: quick resistance changes go to the tvoc and the base value over time transfers to co2... and hcho looks completely faked... I couldn't figure out from what... maybe a random value between 0 and 10 when tvoc isn't 0
I once spent almost 2000 dollars on a telaire co2 detector for the routine testing of air conditions in an agricultural facility, quite the unit it was so accurate I couldn’t even breathe while testing lol
We have quite a few Winix air cleaners and their sensors are rather sensitive to farts. Needless to say, these have been a source of endless amusement. No way someone is getting away with farting in the house without getting caught.
Hi clive, thank you for the video. I happen to work at a company that produces various gas sensors. It is quite common for manufacturers of cheap devices like this to use metal oxide sensors to determine a so called "CO2 equivalent" reading. The sensor actually measures the amount of volatile organic compounds (VOC) in the air and as long as the sole source of both VOC and CO2 is people, there is a quite good relationship between the two. Of course this doesn't work in environment with artificial VOCs. The reason for doing this is that metal oxide sensors are much cheaper than NDIR or PA Sensors normally used to detect CO2. Of course I agree, that the marketing for this device is not completely honest, it does not measure CO2, it measures VOC and calculates a CO2 equivalent reading, as a total VOC reading is not very easy to grasp for the end used. We actually discourage the usage of "CO2 equivalent" readings in favour of an "air quality index" which just tells the end user if it would be a good idea to open a window.
I am surprised you haven't campaigned to safety authorities to get these things banned Anything which can miss high levels of CO2/CO (false negatives) whilst also giving alarms (false positives) when they're not present will fool consumers into thinking they're working properly Yes, some of these are sold as monitoring CO as well as CO2
Years ago at a remote scottish BR driver depot, to save money the train crew supervisor was replaced with a breatherliser machine fitted. This was to save money. A driver booked on who had fish and chips with pickled onions for lunch and the machine mis-read vinegar for alcohol and wouldn't book the driver on. So the next day all late turn drivers had fish and chips and pickled onions for lunch. Within a fortnight, it had been ripped out and the TCS was re-instated. This was reported in Rail News in the 1980s.
Thanks for the video Clive! After testing mine with 99% Isopropanol (no effect), I decided to take a closer look at it. The internals look completely different. Different PCB, different Display. It seems to have a MH-Z19E CO2 Sensor, that is installed on a separate PCB. It's display has a flat ribbon cable and uses a STM32F103 processor. The Battery(1200mAh - floating in the case) and the DHT-11 sensor were included though. 😃 From the looks of it, it could be repurposed for other things too. It would just need different code for the MCU.
Co2 sensors are common because Asian countries (at least Japan)started recommending /mandating that all public venues have them at the start of the covid pandemic, in order to show sufficient ventilation in a crowded room. I believe the suggested max level was around 1000. They are still in place everywhere
Clive, I used to repair Co2 meters used in greenhouses, they were an old design, an heat source at one end of a tube and photo cells at the other end, it works with air sample pumped in the tube and measures how much Co2 that absorbed the infrared
I have been designing and installing such devices were it is very important that they do correct work. It is so irresponsible and potentially dangerous to put these on the market. Great work Clive!! Keep it up!
Especially given a similar design was sent out to schools in the UK for use in classrooms to help them balance disease prevention with heating requirements given how expensive energy is at the moment. That's designed to a spec though and only has 3 colours, lighting up one at a time from 400-800, 800-1500, and 1500-5000, to match previous models that had been produced from the Chinese factories that Rexel (who got the government contract for the CO2 monitors) had contracted out to.
CO2 is good to measure as a proxy for air/ventilation quality, especially in terms of trying to inhibit the spread of infectious diseases, alongside how high CO2 levels tend to make people feel pretty sleepy/crappy. Had long wondered if the super cheap CO2 sensors I'd seen on sale were just VOC sensors, as actual CO2 sensor modules themselves are usually at least 70% or more of the price of them, big part of why I ended up putting some together myself. At least this way I know with certainty I'm actually measuring CO2 itself.
These tin oxide sensors *can* be surprisingly clever. As you said, the gas in question is stealing oxygen from the tin oxide making it more conductive. The sensor can't identify specific gasses but depending on the power of the heater it can narrow them down. A "low temperature" sensor will only respond to very reactive gasses like formaldehyde and carbon monoxide. "Medium temperature" will also respond to alcohols and ethers and "high temperature" will respond to any gas or vapor that can be oxidized including things like butane and mineral spirits. With multiple sensors it is possible to program a "smart sensor" that can distinguish, for example, ethanol from propane. But no amount of clever programming is going to detect CO2 as it doesn't react with tin oxide.
I notice the care you take with the utterance of "nic...o...tine" to avoid upsetting the mechanical censors. You could always tell them you were referring to that notorious supervillain from early 80s public service comics, Nick O'Teen.
I often refer to my devices as a "Personal Electronic 'Nickelteen' Inhalation System". Though speaking that as an acronym may also trigger a censor-bot.
Clive, I bought one looking like this for about €40 during the lockdown and it works perfectly well. I have tested it in CO2 atmospheres in our university chemistry dept and it gives a fairly accurate CO2 reading. Put a cloth over your head and breath inside it with the sensor for a minute or two and you should see the CO2 level rising to 1000+ ppm. Take it into the toilets and you will see the HCHO (formaldehyde) and the TVOC (total organic volatiles) go high, due to the cleaning materials used. The CO2 will go up also as the sensor is not specific to CO2 only. I am guessing your one was either a cheap clone or else missing a sensor - faulty manufacture and/or QC. "One swallow does not a summer make!"
That's always the case, you can always pay double for random Chinesium gadgets on ebay if you like. Unless there's something you know is actually expensive in there (e.g. special gas sensors), I usually aim for the cheapest one I can find for stuff like this. Only exception being if the manufacturer is known and there are known fakes/clones out there that don't work as well, then buy from the source/authorized sellers.
There do exist eCO2 sensors, such as the CCS811, which use a TVOC sensor and some maths to estimate the CO2 in the room. Of course, if you just want an indoor air quality score, TVOC is a perfect metric anyway.
Not in my experience with the new Sensibo air quality monitor vs an actual CO2 sensor. We burn candles indoors and the eCO2 sensor is useless for that use case. I returned the Sensibo.
@@mrtechie6810 Well technically burning a candle does taint your air quality by the fact that you're burning something and releasing micro particulate matter into the air in your internally monitored space.
@@longnamedude3947 not enough to matter, apparently. The CO2 levels increased from 400 to over 1000ppm, but the TVOC and PM2.5 sensors in the Sensibo did not measure anything significant.
@@mrtechie6810 Well that's based on current health guidelines, and having seen the various changes globally by regulators on what the maximum level of various particulate matter should be in the air for safe and healthy living I wouldn't be surprised if a lower level for total volume of particulate matter per m² changes in the following 10-Years as new research into things unveils hidden dangers we may not have previously been aware of.
This is really interesting. My Uni put two of these units in one of our computer labs alongside a UV purifier, which I think was part of a test to see whether the HVAC was actually filtering the air. They were slightly different as they were in a white case, the beeping tone was faster and I believe they charged using Micro USB; other than that, exactly the same, including the layout of the display. It's interesting to think that they might never have been accurate at all. They did sound the alarm rather frequently throughout the day but the only potential sources of alcohol would've been hand gel or cleaning wipes but we never used either that excessively so maybe they were genuine or possibly detecting something else completely. The purifier they were using sensed PM2.5 and that never had to increase power to clean the air so they came to the conclusion that the air was being cleaned already and removed it and the sensors 6 months later
I got one that has a similar UI from amazon (the INKBIRD). It claims to be an NDIR measurement and it definitely seems to work. In my room after I sit for a while it can get up to 1500, but open the window and it goes back down to 600 ish. Set it on the top of a seltzer bottle and it maxes out.
I looked up a lot of information about these things before buying an Aranet 4 CO2 sensor which actually does contain a proper NDIR sensor. Basically all the cheap CO2 meters do the same as the one choice took assist because measuring CO2 actually requires more expensive components.
I went through three CO2 meters from Amazon that worked properly for about two weeks and then "soft failed" where they indicated a safe atmosphere even though it was toxic. I gave an objective but negative review after the third unit failed under warranty. The OEM reached out to me and is sending me a redesigned unit for testing. The bottom line is that there are similar looking units that actually have fairly respectable manufacturers taking responsibility for the product. I have a winery and need affordable sensor in some spaces that have an audible alarm and can be checked over the wifi network. The units that failed had all those functions, but did not last...
If I buy a CO2 meter I want it to measure CO2, not alcohol. CO2 meters are good to measure lack of ventilation. You are not going to detect this with an alcohol detector unless there is a drinking party going on. Good to see that someone exposes this problem.
I worked at Microsoft in a building they rented back in the 1990’s. They changed the cubicles to only 6’x6’. Everyone got headaches after 3pm. Back then it was expensive to test co2 but after months we got them to test it. The level was above 2000ppm. They upgraded the hvac system fresh air and our headaches went away.
Great tear down! My MIL had a CO alarm with a built in methane alarm. Every time she mopped the floors it went off. We figured out it was alcohol in the cleaner that set it off. Probably a similar sensor. It got on her nerves and she chucked it.
That latching power supply reminds me of what you had to do before microprocessors/controllers had low-power and sleep states. One such design I was involved with back in the late 70s involved used a Z80. In order to power it down when not doing anything the trigger inputs went to a CMOS XOR gate, the output of which switched on power to the Z80. The other input of the XOR was from a CMOS latch controlled by the Z80. Sequence was a change of input switched on the power to the Z80, Z80 held on the power, did its thing, set the latch to the same state as the input then killed its power.
I think a microprocessor "keeping its own power button pressed" is still the best solution for battery life, because you can get truly zero current when turned off. A sleeping low-power micro might drain the battery in e.g. 3-6 months of non-use, whereas a disconnected battery stays full for many years (especially non-rechargeable cells). It's silly that adding a transistor used to cost money, but these days they can be cheaper than the cost of the bean-counting and re-engineering required to make it work without one. Though that doesn't stop bean-counters from demanding the removal 😆
@@renxula FWIW I've got a bit of test kit I built back in 2013 using an ATtiny13A which goes into deep power down when not in use. Iq is less than 1uA and it still works fine on its original two AA cells. As they're now in the danger of leaking zone I might swap them for a 123A lithium cell.
If you are living in a house with 4 walls and a roof the co2 levels will rise quite fast with 4 people or more, no need to hermetically seal your house, our living room goes up to about 1200 after 2 hours with 4 people, this is not dangerous but it is above the recommended limit here (1000)
I come across C02 monitors at work as a Supermarket Refrigeration Engineer, either CBISS or CPC. They can be configured for HFC or C02 refrigerant. They are networked to RDM panels, so alarm along with the fridges, they're usually set for 3000, 5000 & 15000 ppm, with c02. They take a baseline reading, then compare that with readings from every channel throughout the store. They're not cheap £4000 to £5000 if I recall. We also tend to have a few issues with them, pumps, IR sensor bench or PCB failure
The sensors reaction can be explained by the cross sensitivity of these sensors. For my work I have a BW GasAlert personal gas monitor and it measures oxygen, CO, H2S and LEL. The CO (not CO2) sensor is extremely sensitive to alcohol. I discovered that when I had hand disinfectant on my hands and brushed the sensor with my hand. The thing went through the roof. The CO sensor is also cross sensitive to hydrogen, hold it close to the vent of a charging lead acid battery and it reacts as well.
I think a portable CO2 metre is very handy providing it is good quality. If you go into a room when there's a meeting, sometimes it's like being on a stranded submarine. Having a CO2 metre prevents any arguement about opening doors and windows, particularly in winter. Also it's very interesting if you sleep again in winter with all the windows and doors shut good to know that you're not getting high CO2 levels in your bedroom.
It's not a fake. The description of these units on Amazon (eg) states correctly that the detection method is "TVOC", Total Volatile Organic Compounds. In other words they're designed to detect levels of anthropogenic VOCs which are generally produced alongside CO2 in human activity such as respiration. So the level of VOCs in the air inside a building where human activity is taking place is an indirect indicator of CO2 levels. VOC detection is a lot cheaper than direct CO2 detection allowing these units to be produced for a fraction of the cost, but yes the downside is that they are easily fooled by introduction of VOCs without CO2, or vice versa.
I've got a CO2 meter here at my home as a detector for when to open the window (it also contains a hygrometer). On the back it says "NDIR", so I hope that it is not faking the values. I like these devices, since you mostly don't recognize your own smell. I guess that the sensors aren't calibrated very well, but they fulfill their purpose.
Quite interesting that you got the result you did. I have a very similar looking model at home that I paid decent money for from a reputable store. Mine has the exact same screen, however it has a white plastic box, not a black one. Looks like it might have more vents on the sides as well. If I blow on the back of mine, it jumps up to 2000+, but not an instant 5000 the way you see on yours. I did a little test of rubbing some isopropyl alcohol on my hands the same way you did and then providing the fumes to the sensor and it didn't move at all. It would appear that not all Chinese made CO2 meters are equal.
I was worried that mine was fake after seeing this videos, but luckily mine has a white background and was also bought from a reputable store, glad to know that I most likely wasn't scammed haha
I'm going to have to try the alcohol test at work. We have very similar looking things and they are always going off with 1500ppm readings. Even when it's sitting right next to an open window in the hallway. Now I wonder if it's the ritual hand sanitizing setting it off.
So a VOC sensor instead of a CO2 sensor inside? I guess VOC was cheaper... (Also, the demand for CO2 sensors is because CO2 is a reasonable indirect measurement of ventilation in a room which, y'know, kinda important during a pandemic with an airborne virus)
Actually not just pandemic useful, our ability to concentrate and think drops too as the CO2 concentration goes up. So pretty important in general even at home, but I'd expect employers to ideally want the employees they pay to function well. Same with schools that try to teach children, so many of them sitting in one room seems like a great way to quickly get the CO2 above the 1200-1500 ppm where things go downhill quickly if there's insufficient mechanical ventilation while the windows are closed. It'd take a lot more than the usual 1200 ppm threshold for "bad air" to make it actually acutely dangerous but a few real sensors with useful displays probably wouldn't hurt to remind people to do the right thing. Ideally you'd want the ventilation system of the building to measure the CO2 levels in the room though and adjust what it does as needed, that way you're wasting less energy on extra heating/cooling during low occupancy periods and can prevent the "I don't want to hear the noise/feel the moving air" humans from turning it off. I did get one actual CO2 sensor myself and it's a useful reminder at home, if I keep the doors between rooms open on most days it stays nicely below 800 ppm or just above with just me and my two cats. 3 or more people for 30 minutes or longer will quickly turn things red, it's a good reminder. But oddly enough there are days without visitors when it does trend towards over 1200, must be the wind direction and force affecting normal passive air exchange in this old house. Closing a door to keep cats away from electronics components and soldering irons also raises it quickly, indoor exercise even faster. I am looking forward to exposing the sensor to some other gases now though to see if it triggers on any other ones I can easily produce.
@@extrastuff9463 With my NDIR based CO2 detector when the oven and hob are on for a long time downstairs the CO2 upstairs seems to rise significantly could a cooker be doing it?
@@cnafyi Honestly no idea, since you mention CO2 and the oven I assume that one is gas powered and not electric? And while running either or both is that with the some kind of mechanical extraction to vented to the outside being on preferably near the hob? (traditionally above it here where I live). If that's done and doors to hallway and upstairs stay closed I'd expect the impact to be minimal but I never really measured it. Could try measuring it in the near future, but I have a gas hob and one slowly heating old traditional full size electric oven + combi microwave with a functional small convection oven that heats up quickly. So much less CO2 being released into the room along with a noisy but effective extraction fan above it. And maybe measure it again when it's warmer weather when I often leave all doors to upstairs open so the cats can roam freely, currently not done to reduce the heating bill. My kitchen, living room and bedroom are all downstairs. Upstairs is only for my storage and hobby room, treadmill and other exercise equipment lives there. Measured using that with closed door and window a few times, it gets the CO2 concentration above 2000 quickly given that it's a tiny room. Leaving the front door downstairs open and partially opening the upstairs window solves that problem though.
It could be a VOC (volatile organic carbon) detector. Those are often in packages with humidity and temperature sensors. You can probably also detect other vapours such as acetone, acetic acid (vinegar), perfume etc. It probably does not react to butane and similiar alkanes because they are much less reactive.
Volatile Organic Compound, not carbon. VOCs have carbon in them, but they're just chemicals with low boiling points, thus they easily transition to gases (which is the definition of volatile).
If you have an actual CO2 meter, it's a pretty good proxy for how well ventilated the area is. And it's also pretty well correlated with your risk of catching airborne illnesses from other people in the room.
I just looked at this board and the real sensor 2 days ago on Ali. I made a real CO2 and PPM2.5 displaying thing a few years ago and now wanted to make a few more. The "real" sensor this was made for was a MH-ZH19 NDIR Sensor - you can grab one for about 17EUR.
although some could be straightforward and easy to make, sensors science is a really interesting field, it covers lots of knowledge in chemistry, physics and maths obviously and the technical challenges of making them at a large scale! fascinating! Thanks Clive for the great effort of reverse engineering these things up!!
Change the 10K resistor in series with the sensor, to change the scale down of the reading ( so that it does not over range ), then use it for a party drunkeness meter?
Fun and infovideo as always Clive! I have two of these sensors, one CO2 and one fine particle, both in same housing you show, only with Micro-USB charging. Both work fine, and the CO2 sensor goes to 400 for a period of time sometimes, in fresh outside air just over 430 ppm and inside depending on people in the room and ventilation. Similar values as a professional one. The fine particle one is also quite good, detects when the fireplace is (not often) lit, and has an internal small fan for airflow. Will test the cross sensibility with Alcohol 😉🍺🍷🥃
One thing to note about CO2 sensors in general, they're quite slow to respond. The one I'm using in a project is from Sensirion (the SCD40) and it can only put out a reading every few seconds, and that reading won't be all the way to the actual current value, generally. So even if this was a legitimate product and not using a temp-humidity only it might not respond well to a quick blast with the Sodastream, since the CO2 would largely dissipate before it the sensor managed to update fully.
As far as I remember, CO2 sensor values need to be corrected according to the ambient temperature and humidity. So adding a sensor for them is reasonable. It would probably be better to use something more accurate than a DHT11, though. At least if they had used a real CO2 sensor...
My NDIR CO2 detector responds almost immediately to a strong source of CO2 such as my breath. A SodaStream blast has 20x the CO2 concentration of breath, so any true CO2 detector would quickly spike in response to that. But it can take ~30 seconds for the reading to stabilize, as the gas needs to diffuse across a membrane into the detection chamber.
It's a CO sensor. CO is a reducing agent and it gets catalyzed on a piece of platinum wire. It's the same sort of sensor as the alcohol ones but calibrated and produced differently. As for what they react to, most alcohols, I would say esters are a safe bet too, like ethyl acetate, acetone, hydrogen, and ammonia. Second to last blows up on contact, last one turns into the brown unwanted gas.
Interestingly the Scottish building regulators now seem to require CO2 meters to be installed in the main bedroom of new build properties where there is less than a certain level of airflow in the room, seen them in several different properties built in the last few years.
*Hermetically sealed building* An office block I worked was being refurbished. Idiot in charge put in air con with no fresh air supply, and then *sealed all the windows* . People were falling asleep, complaining of headaches etc. Temp in HR had a CO2 meter (they were an environmental health officer before) went round and found high CO2. So they sacked her, and had meeting were said idiot stated "well we aren't opening the windows!" When people complain about where they work I always trump them with "did they take away air from you" The year before They refurbished the heating on one floor, but didn't turn it on (ceiling ac units) , people were seating in sleeping bags at their desks with wooly hats and gloves!. Our floor was baking, I used to go down to them in just a shirt and complain about the heat to wind them up.
In the USA, for decades mechanical codes have required a fresh air intake in commercial buildings. Also required for residential houses starting sometime in the last 10 years or so, if the house is too "tight" as measured with a blower door test. (I think most builders just plan to make the house tight and install a ventilation controller to pull outside air in--if the house isn't tight enough it will fail the blower door test).
@@yesihavereadit Sort of--most jurisdictions require an inspection. If the building doesn't have the required ventilation it will fail the inspection, and whoever did the work will have to make the corrections and get it re-inspected. So it's well known that having an idiot in charge of the work is a great way to fail the inspection and have to do it over. Also, the inspector, at least around here, doesn't always arrive at the scheduled time, because some inspections take longer than the 1 hour allotted. So if you have to have a re-inspection that can be 2 or more additional hours wasted waiting around for the inspector. Bottom line: Failing an inspection is wasted time and money.
The co2 reading is directly related to virus levels in the room. If there is someone with covid or the flue in a room and that rooms co2 level goes to 1200 ppm then there is not enough fresh air intake and virus levels in the air are also beginning to rise.
I have used a co2 detector on vacations and at big parties. Almost every bus getting to excursions had co2 levels above 1200 ppm. So I put on an n95 mask. Thanksgiving at my house is 25 people. Co2 gets to 1800ppm if I don’t have the circulating fan on. I can actually control the enthusiasm of conversation by playing with the co2. Allow it to go above 1500ppm and the room gets quiet. Bring it down to 800 ppm and people start talking again. It’s kind of funny to play with.
Рік тому+1
The idea here is actually good given that the device measures CO2 properly. I actually sometimes had a little problem with CO2 in my old apartment. Living room was maybe 20 sqm. At 2,5m height it's 50 cubic meters. Let's say that we have 8 people there and the room is sealed (maybe it's a cold winter or very hot summer and you run a lot of AC in closed loop so you want to save on air exchange). In just an hour you will reach 1% of CO2 concentration which already feels stuffy and not fresh. If you'd continue, after 8 hour party in such sealed room it will be over 6%. Very high and dangerous (the actual limit for workplaces is 1% for 8 hours or 3% for 15 minutes). Now it seems unrealistic but it's enough that you don't have enough ventilation and you may have problems because of this. The problem is that although alcohol level in the air may reflect how stale the air is on the party, it's not giving us much. In my office we have booths used for short meetings. Those are roughly 3x3 meters, so around 40 cubic meters. You have a meeting with 6 people in it. After just half an hour it's over 0.6% which is already not comfortable and affects how people feel, in an hour it will exceed the allowed concentration. Despite having some sort of ventilation, those don't have enough airflow and are soundproof, so they are actually sealed from the open space too. It's a bad design and it can only be used for up to 15 minute meetings after which you need to leave the room open to vent it out. If you have a few meetings in there one after another, people don't even want to get there as they start feeling bad after a few minutes. If only they would have a working CO2 meter in there.
So glad I didn't buy that one. It's cheap. But the one I got had more review and a better rating. Also, a non alcoholic exhalation with raise the numbers. Cooking on my gas stove without the range hood venting also raises the numbers. One time making fig jam I had the large burners going full throttle and it set off the sensor on the other side of the house. It is good to have a co2 sensor. I now use the vents and open the windows more often. I have the Forensics Detectors FD-CO2000.
Interesting...I have one of those bought from Amazon Canada, and it does detect CO2. If I breath into it, the CO2 reading jumps dramatically (1,200 to 2,000), and then slowly returns to normal (high 300s, low 400s). When I tested, I had no alcohol or nor do I vap. I bought it since I wondered if I had a exhaust leak on my Subaru, and I put it onto a car window mount, and I was driving along in winter, and suddenly it read over 4000-5000, and I had noticed that I was getting sleepy. So I opened the window and the count dropped slowly back to normal. And I do have an exhaust leak.
I was considering this very same 'monitor' from amazon. There are a number of them but they all have the same 400 floor value and I could not understand why. Now I do. Thanks for the comprehensive teardown and the laugh at the alcohol sensor called CO2.
The same sensors are being used in various Tuya enabled devices sold as CO2 sensors. I got 2 different ones, they also go wild near isopropyl alcohol. We were making mussels with white whine, when the bottle was standing open next to the sensor, it started to trip the alarm “GAS detected, evacuate immediately”, while we were cooking electric :)
6:27. "There's something really annoying about this." I watched the next scene a dozen times, at least. I still don't understand most of what you said. But every time, I laugh my a** off at your delivery. Bravo!
I got an identical-looking model recently. Testing it, it definitely reacts to alcohol (I got extremely mad when it worked), but it reacts to the breath of extremely sober people too! So it does seem to detect (something that at least approximates to) CO2.
Just because it reacts to breath doesn't mean it reacts to CO2. Breath contains trace amounts of alcohols and formaldehyde that the device may be reacting to. Test it with an actual CO2 source.
This is likely used for indoor grow rooms where higher co2 levels benefit plants because that is their food. Temp and Humidity are other typical grow parameters that are monitored.
I've used uCs to run multi-digit 7-seg LCDs directly. The segs are brought out separately, and one common lead. You alternate all signals between 30 to 50Hz. ON segs are out of phase, and OFF segs are in-phase, relative to the common. If the uC stalls, you just polarized and wrecked the LCD. Of course, the designer of this unit would take care to use the uC's watchdog timer, to prevent this from happening, just as he was careful enough to buy the "correct" CO2 sensor ... yeah !
Just got given a load of these courtesy of some government department, nice long type C cable, USB charger looks nice. Reads twice as high as the old ones we had. Humidity reads around the same
I have a CO2 sensor that's _almost_ identical but with a whole bunch of very tiny differences: - "PPM" label is less bold and the "CO2" label is 3 characters of equal size and position - the digital display stays centered and does not employ a leading zero - the level dial has a gradient outline surrounding the 4 intensity marks - the battery indicator has no opening on the right and the fill meter inside is continuous - temp symbol is a thin line figure representing a thermometer, with scale lines across it (instead of an outline-plus-fluid depiction) - humidity and temp numbers are in a bolder and smoother sans-serif font - there are no "temp" or "hume?" labels, just symbols - the side perforations in the body are smaller, simpler, and more numerous - and most substantially, the port is micro USB Perhaps most importantly, however, I can easily max it out (at 6,000 PPM) by slowly exhaling into it, and it is completely indifferent to alcohol. It also roughly agrees with various other CO2 sensors I have. I guess mine is the real deal.
@@roybarton9617 PPM is a measure of concentration; like percentage but at a smaller scale. It is ubiquitously used for expressing CO2 concentrations. So if TCs air quality detector was decent and not fake like in this video, then yes CO2.
You unkowlinly just answered an issue I have with my new nightcore headlamp. It uses usb c but does not charge with smart pd units. They must have left out those resistors.
I almost bought this device a week ago. I bought a CO2 meter, ended up with the Airthings View Plus, to track CO2 levels while I sleep. My bedroom occasionally reached 1500ppm while I slept, and after a few data points, the nights where it reached that high correlated to days that I woke up feeling lethargic and having an “off day.” Tracked it down to A) poor air circulation in my house and B) insufficient air flow to my furnace. I rent and the previous tenants stuffed rags in the air supply vents since they allowed cold outside air straight into the basement. Sleeping with the bedroom door open and setting the thermostat to turn on the air handler 15 mins/hour, regardless of turning on the heat, seems to have mitigated this issue. Of note, I believe the Ecobee Premium uses this method of indirect CO2 sensing. I think the proper NDIR sensors are like $50 for the module itself, hence cutting corners for cheaper sensing devices.
A 400-ppm increase (so, from 400ish to 800) in CO2 concentrations can lead to a 50% decrease in complex strategic thinking, that's why they measure it.
A similar model was sent to schools last year, but they are NIDR sensors and only have 3 colours not 4 to match the previous monitors that were sent out in earlier batches. Assuming the firmware is similar, your speculation about calibration is close. The instruction booklet we received said that before first use you were supposed to take it outside, leave it for 5 mins (as NIDR sensors seem to take 5 mins to get an accurate reading), and then quickly press the power button 3 times to calibrate it. It probably read 400 when you were outdoors as that's the lowest number it can display.
I just bought a variation on this and it detects alcohol, it detects natural gas from our cooker and it also goes off after a particularly prolific fart. If I use the toaster it goes off and the levels go higher when we cook (either in the air-fryer or the gas cooker). Mine purports to detect TVOC, CO₂ and HCHO (formaldehyde).
Inspired by this teardown, I pulled apart an almost identical detector I had (labelled H8 Plus, not H8). Same thing- a no-id markings VOC detector unit. Cunning thing was that at several places on the circuit board, there were screen-printed labels 'CO2 SENSOR'. Suggests that manufacturers have felt the need to up their game with an increased level of deception.
The only use I can think of for a device like this is for greenhouses which pump CO2 into the growing area on a schedule to feed the plants. Usually this coincides with disabling the ventilation, and having a hard reading of the CO2 values as they fluctuate with the high plant load will give you an idea of the health of your crop. A relatively new hydroponic tomato farm near me does this.
Interestingly, I have a CO2 detector that looks identical, including the label, except the case is white, and I didn't buy it from ebay. It seems to actually detect CO2 spikes when I breathe on it at least (without having had any alcohol), so it looks like the one you have is a fake based on a model that (probably) actually works. I got it because I was concerned about CO2 levels from having a gas stove/oven and furnace, but turns out my house is old enough that it's quite leaky and not a problem.
Thank you Drunk Clive, that was interesting. I have quite a lot of different snsors, I might get one of these and see how they perform when I swap them over.
A distributor or manufacturer of one of those monitors contacted me to do a review on my channel. I said sure but when I mentioned in my company I have various gas monitors so it would be great to give it a full test. All of a sudden they had filled their quota for reviewers and didn't need me any longer. 🤣
I can personally say that, having a reputable detector, my indoor bedroom CO2 levels range from 800-1200, which I am none too happy about. Once when I had a guest over it spiked over 2000 and I found out it had a default alarm setting.
VOC sensors on a PCB can be bought for a fiver and linked to say an Ardunino. I am going to use one to boost my all house ventilation unit when it detects cooking etc. VOC is a better measure of such than CO2. It does provide an eCO2 reading too but I ignore that. Also has a humidity sensor to detect say showers. The sensitivity is amazing. Move your hand near it and the VOC reading goes up within a couple of seconds.
48-pin PIC (18F5xxx) chips seem to have power directly opposite on pins 6,7, 31,30 whilst the ATmega809 uses 14,15, 28,29, 42,43, which may help with ID.
Where I work, we purchased some devices that look identical to this one indicate where we might require better ventilation during post-lockdown restarting of meetings in our rooms. Ours very much appear to detect co2 rather than alcohol though, due to the fact that our site is a church and therefore consumption of alcohol is restricted to limited and specific occasions. 😉
Worked with Sensidyne Flammable gas detectors years ago, operated with a wheatstone bridge, catalytic bead resistance circuit housed in a sintered cap, gases methane, hydrogen, ethers and alcohols, all detected using this type of sensor.
The chip part number is likely etched off because, in this time of grey market ICs, reselling is common. Many contracts for OEMs will state that they cannot resell parts. Part manufacturers keep track of where batch numbers are sent, and thus know who the scalpers and second sellers are.
In an enclosed space, CO2 levels are an excellent proxy for viral transmission risk, so they have been used to regulate ventilation in enclosed spaces where people congregate. Our restaurant at work has windows hooked up to a CO2 monitor, so as soon a threshold is reached, all of the windows open, then close again when another threshold is reached, after the CO2 level drops. This automation allowed the 2m separation restrictions to be relaxed earlier than most people would have been comfortable with otherwise.
It's worth noting that there have been studies that show that poorly ventilated offices have high enough co2 levels to cause significant decreases in ability to concentrate
I don’t think it was one person/company involved. The sensor supplier was probably scamming the company making the full devices. like „oh you want a cheaper co2 sensor? sure we built one…“
I think you are right about it being a ghost detector, it seems to be quite sensitive to spirits.
Tish-Boom
We have a winner here folks.
@RichyJAdventures Well done you won the "Ponzi Scheme Twonk Award" - How do you feel about this great achievement in your life?
LOL
Indeed
Maybe the circuit designer got his sensors all mixed up in a box and thought "the one that reacts when I blow on it must be the CO2 sensor" - too bad he wasn't entirely sober at that time... 😂
Good one 😁👍
I was thinking the same thing. Try putting other types of sensors in there. (?)
that makes sense 😁😁
dude thats awesome
methinks these days anyone's more better off not bein' entirely sober
"Unless you live in a hermetically sealed building" our office moved to a whole floor in a WeWork a few years back, and it always felt "stuffy" in winter. Towards late morning I was always fatigued and sleepy. I put it down to the coffee.
Someone else bought an proper air quality meter and we realised that in winter, the CO2 levels in the 200-person office would rise from 9am through to about 2pm, and the moment they hit 5000ppm they would drop abruptly and hover at a lower level. This pattern repeated every day.
It seemed that to save money on heating WeWork had configured the HVAC system to let CO2 rise up to the legal maximum before they let in outside air. Unfortunately, you start feeling drowsy and foggy around 2000ppm. Without the CO2 monitor, we would have blamed the coffee - because it would be crazy to suggest that a company was suffocating the workers to save on the heating bill.
"because it would be crazy to suggest that a company was suffocating the workers to save on the heating bill." I think the existence of an office episode with this exact plot, albeit one of the more 'realistic' plots says otherwise
I wouldn't blame the office immediately. They could have simply set the limit too high (legal maximum = recommendation) to let fresh air in. You just need one or two people who don't really know about the effects of high CO2 levels and simply see the heating bill.
Also, there are very effective ventilation systems which conserve up to 98% of the heat. So there's really no economic reason to not ventilate the air - not even with only 85-90% heat conservation which is standard.
Ventilation is way more effective than windows so it might be a good idea to propose such ventilation. Especially from an economic standpoint more efficient workers are better for the company.
Nono it's COMPLETELY on par for companies to suffocate workers these days to save on heating. Especially where i live where costs went up 500% recently for large companies. Absolute insanity.
Making employees suffer to shave just that little bit more out of the budget? That sounds *exactly* like what a modern company would do.
There is a reason wework went belly up lol.
The auto subtitles perfectly spelling "n-i-c-o-t-i-n-e", dashes included, is pure sass.
Why can't you say it ?
@@MrTeen-ul7ycUA-cam frequently demonetizes videos that mention smoking/vaping.
They updated the algorithm: Now it's just "Nick O 10"
Still funny how he had to pronounce it slowly
@@anno_nymNo, he says it twice.
We have real CO2 sensors in our office building, with LED lights that go from green to yellow at 800 and to red at 1200 ppm.
I designed and built them myself (around 150 sensors for the whole company) at the time we had all those mask and quarantine regulations.
They contain the Sensirion SCD30 sensor module, which uses NDIR to detect CO2, which is accurate, but also quite expensive.
They do help a lot with air quality monitoring, because as you mentioned, humans exhale CO2 at all times, and if too many humans are in one room with bad ventilation, the levels rise quickly. It will never reach dangerous levels in a normal building, but at 1500ppm and above CO2 causes headaches and reduces focus, which is usually a bad thing in work environments.
High CO2 levels also mean a lot of exhaled air and therefore higher risk of aerosols (virus transmission), so respiratory infections have declined since we use the sensors and therefore ventilate the rooms when needed.
I bought one for my home last month. It is really good for disciplining me to regularly open the windows to vent in fresh air when it turns yellow. And it's been doing wonders to my general wellbeing so far.
We also have them at work, also introduced during COVID for the same reason.
Some of them in the workshops are linked to extraction systems and will turn on the extractor if the value goes high.
In the UK, there was a move by a lot of amateur choirs to use such sensors as a way of getting back to rehearsing in person after the Covid lockdowns. Someone thought that choirs were a prime source of virus spread, and government took that view to heart, so choirs had to observe prohibition and then physical separation and masks far longer than most other groups. When the rules were relaxed, I bought a sensor from Amazon for around £40 - it looked somewhat like the one you took apart. It quickly became obvious that it was of no use as it sat there the whole evening of a rehearsal at around 420 ppm with very little variation. Now I see why. We didn't have a bar open, so we couldn't test it for alcohol. I'm glad to say that someone found out a much better technology and we used a sensor of that second type for a long time to check the air quality. I still use one in my bedroom - as someone said, it's good as a reminder of when to open a window.
Its a shame it was done mid pand, it would have interesting to see if the drop in respatory illness would be present still, cool stuff.
A couple of years ago I parked in a parking garage that had CO2 sensors on the walls. I don't recall who made them but I looked them up and they cost a couple hundred dollars each. I'm pretty sure that they were wired to control the ventilation fans, probably an energy-saving measure compared to just running the fans all the time.
I have used NDIR-based CO2 sensors (MH-Z14, MH-Z19) in an office setting, and it was quite interesting to note the average levels. After seeing the PPM levels in a meeting room zip past 2,000 ppm with about a dozen people inside for an hour, it made sense to me that one would start feeling drowsy and lose focus during such meetings. It's not just that they're tedious wastes of precious life minutes.
A number of studies have been performed on the impact of CO2 levels on cognitive functions, which show that a rise from ~400 ppm to 800 ppm drastically reduces one's ability to perform even basic office tasks. It's like being sleep-deprived, or tipsy. Beyond 800 ppm it just plummets and by the time you hit 2,000 ppm, individuals will begin to get headaches, start feeling nauseous, etc. At around 5,000 ppm you'll have people literally passing out, with a number likely having puked up their guts before then.
In the open plan office of this place levels got to 800 - 1,000, which was a good hint to crack open a window, which helped a lot. In that sense, CO2 sensors are an invaluable tool to keep track of air circulation in a building, and the build-up of stale air. The same project (BMaC: Building Management and Control) also got used for other purposes, such as keeping track of the number of cups of coffee drawn from the machines via their serial port, which provided an interesting comparison point for CO2 levels and coffee consumption :)
That was really interesting!
My bedroom reaches 3000 ppm sometimes. I guess i am used to it...
I followed the same rabbit hole, working in an environment (one most would expect to be as conducive to best practice as possible) we're levels were regularly 1000-1400. When I mentioned to the HSO the same research you refer to, it was dismissed as a waste of time. The fact people regularly got headaches and underperformed in this environment, never seemed to crossed their mind. Ah well, that's life, just glad to see someone else has made the same connections as me about CO2 levels.
@@nutzeeer used to it you may be but for goodness sake, change your norm.
@@mr_b_hhc I just aired out and now I am at 640 ppm. Woke up to 2700. I could leave my bedroom door open but I wake up easily
There's "zp16" written on the board, which is a VOC air quality sensor. The empty place for "infrared module" would be for the actual infrared CO2 sensor.
Aren't actual CO2 sensors electrochemical? IIRC ones used in multigas detectors are electrochemical.
@@macieksoft CO2 may be detected by infrared absorption or by electrochemical means.
@@macieksoft electrochemical ones very often measure carbohydrates/VOC and by proxy measure "CO2 equivalent". They are much cheaper though than infrared sensors and often found in cheap "CO2" sensors. Infrared sensors is what you want for properly and accurately measuring CO2 levels, but they cost a lot more: cheapest NDIR sensor I could fing is MH-Z19 and it costs 15-20$, while electrochemical one can be bought for less than a dollar
BTW a lot of those infrared sensors actually use the same data protocol used in flashing firmware/debugging microcontrollers (UART), so there's probably a revision that uses NDIR sensor
Upd: there's also apparently a newer sensor SCD40 which uses I2C instead of UART
@@aleksandertrubin4869 That cheapest NDIR sensor seems much cheaper than electrochemical O2 sensors that I sometimes work with.
This is why I built my own CO2 meter. I knew exactly what was in it and learned something new while doing it. It also logs the data which you can view on your phone.
Got two running in my grow tents on ESP32's, measuring CO2, temp and humidity, calculating VPD and adding humidity as needed, then serving the data as a webpage. The modules seem to work very well, maybe not super-accurate, but reliable.
Nice, you've implied that is in fact quite easy to do so now I'm going to go build my own as well.
There are "CO2" sensors available that in the fine print says they are "CO2e" or "eCO2" sensors. Which means that they are VOC sensors, and the VOC level is cleverly and most often incorrectly used to guesstimate a probable CO2 level, assuming human presence. Could that be the case here?
It may be.
Wow, this is really intriguing, thank you for sharing your knowledge on the matter, it's crazy to think that this could just be a bad product by mistake.....
Having toyed with these sensors in the past I am quite sure you are hitting the nail on the head here.
TVOC sensors often do claim to be able to estimate CO2 - the part on this board looks like either the genuine or a clone of the Sensirion SGP30 or SGP40.
Yeah its a voc sensor. I'm currently playing with an adafruit one connected to a pi-pico-w. It makes guesses based on VOC's. It was 18quid. The Co2 breakout board sensors are 54 to 81 quid a pop. (I have not checked the sensor device only prices but they tend to follow the i2c breakout board with a few other surface mount thingmibobs fairly closely.)
We were having weird headaches and just foggy feelings since moving into our new house. Someone mentioned checking CO2 levels since the house is pretty sealed up. Got a sensor and it showed over 3000ppm, we also have all natural gas appliances. After getting it below 800ppm, we can tell a huge difference.
This recent explosion of information about how dangerous gas stoves are makes me think what it must have been like when they realized how dangerous leaded gasoline and paint was. A "oh crap now what do we do" moment lol
Do you also have gas heating? If it's unflued, this would also be a big contributor.
@@NotBROLL our gas boiler vents crap out of the side of my house, and i often wonder what is it venting other than steam and how much comes back in through my open window
@@skeetsmcgrew3282 leaded paint and gasoline were always known to be dangerous. The claim was that low concentrations were "safe".
FWIW the inventor of leaded gasoline nearly killed himself whilst developing the product (and did kill a few reseachers). Pure teraethylene lead is incredbly poisonous to the point that a single sniff can hospitalise you
"monochromatic display with coloured panels printed over the circular segments" That's pretty much the description of how Space Invaders machines first went from B&W to colour. A few strips of coloured gel over the screen. Sometimes not much moves on from the 1970s.
yes :) The bit of yellow tape over the bottom of the screen.
If you ever build a control panel or instrument panel which requires (or would benefit from) backlit graphics, you may find yourself doing the same. ;) But to find it in a consumer product? Oh hell no. O_O
My nor-tec weather station has the background (above the backlight) printed with a landscape photo, text and different colors for inside/outside display sections. The actual display itself just consists of black and white LCD segments (in different shapes) on top. I find this a nice way of making a stylish looking display, but with extremely low power consumption (and probably price) compared to using a real OLED or TFT. Especially as the display is rather large.
It's a good device, with temperature/humidity/air-pressure sensor built-in, with a radio clock receiver (DCF77) and a 433MHz receiver for up to three wireless external temperature/humidity sensor modules, adjustable backlight and a capacitive snooze button (for the alarm). And you can use it with two 1.5V AA batteries and/or with an external 5V power adaptor.
The "CO2"detector display looks similar, maybe the color is printed on the backlight diffusor, then the LCD just needs to block out the light.?
The Chameleon in-home display for my smart meter does this to give coloured segments, also oled displays I have bought have an option for a yellow strip of pixels on an otherwise blue display to highlight an info bar. This display is also used in an old Alba personal DAB radio I have, the yellow area is used for icons for signal strength, mode, battery state etc. Many AV separates have a monochrome fluorescent display where some icons such as record have coloured panels to change them from white to red or yellow.
CO2 is used as a proxy for measuring air that is stagnant. Mostly in the context of trying to ascertain if a public building has adequate exchange of outside air to help reduce airborne virus spread.
and the sensor is a VOC sensor that uses VOC as a proxy for CO2 in human presence.
Meaning: This device guess air staleness by guessing CO2 Content by guessing VOC content.
Why not skip the extra steps and guess air staleness from VOC content?
Our HVAC system at work has a CO2 sensor in it. If it gets above the set level it opens a damper to pull in fresh air from outside. It's pretty neat to look at the graphs in the reports it can generate and see the level around 425 ppm first thing in the morning and as everyone arrives it starts climbing. Usually just after noon or 1PM the level gets high enough that the damper starts cracking open and the CO2 levels off. If we have an event that brings an extra 100-200 people into the building it will spike way up and the damper goes wide open trying to compensate.
@@sarowie Omg I love that roundabout so much. It's the pinnacle of consumer goods.
Clive, you were wondering why someone would want to measure Co2 content. We use an array of sensors (including Co2) when welding in a tank or bund. Co2 is heavier than air so you end up with the bottom of the tank filled with Co2 and you suffocate. Always good to have something beeping away in the background. Though obviously not this piece of crap.
You’re supposed to have a canary for that ;)
@@joearnold6881 a short apprentice will also work.
Monitoring for air quality in lecture rooms and in our beer fermenting/storage/bottling facilities. It's a useful reminder for airing early to avoid fatigue.
I've got something similar at my work in the soda closet, people tend to leave hoses unhooked and the room tended to make people sleepy before they put the alarm in
@@v.sandrone4268 great idea but I think there's a flaw. Should we call it a fatal flaw? So much for an apprenticeship. They get one chance to learn the lesson.
WOW!
I am speechless, literally: I thought to take that EXACT type of sensor (and - indeed - it was on my AliExpress Wishlist since a long time now): I was waiting before getting one exactly to understand how much them should be considered reliable and... really I have no words, except a huge *THANK YOU* for letting me save my money and search for something better
I knew CO2 sensors were quite expensive and it sounded strange to me finding those devices as cheap as ten-ish euros each 🤯 now I know exactly why
Sharing this video everywhere 💪
Wow! I just received a nearly identical unit in the mail last week! Mine’s the fancier version of this one that “detects” formaldehyde, TVOC, PM2.5, PM10, CO and CO2. But mine actually has a GP2Y10 (dust sensor) module in it. I’m doing a soda steam test right now, but from my first test it just detects alcohol.
It only has one gas sensor in it, so it’s clearly lying about something.
I’ll update this comment with an edit in a few minutes
Edit: just put it in a bag of pure CO2 and the CO2 reading is dropping…
Edit2: Whoa! Whatever sensor they’re using actually does detect CO2 but registers it as TVOC. Somehow in the bag of CO2, it mins the CO2 reading but maxes the TVOC reading. There’s something fancier going on here. I think the gas sensor is actually sensitive to two types of gases, but the math isn’t working properly.
I just breathed 2x beer breath into the CO2 bag, and the CO2 reading started climbing. Man, I wish the gas sensor had a number on it. I think I might have to dremel it open and see if I get any clues.
I've been eyeing these on Ali for some time. I might still pull the trigger.
@@pyromen321 if yours has "PG-L58" on a sticker on backside - we're on the same boat. i was thinking it's a scam, as they're quite glitxhy and prone to runaway (especially when on charger), and battery does 8 hrs MAX. now i'm pretty sure.
I Just took mine apart and it has a reasonably OK particle sensor and separate humidity and temperature sensors... but everything else is "faked" by some calculation from one tin oxide sensor of the hot can variety
Edit: quick resistance changes go to the tvoc and the base value over time transfers to co2... and hcho looks completely faked... I couldn't figure out from what... maybe a random value between 0 and 10 when tvoc isn't 0
Thanks, perfect timing as I was about to waste £25 on one to see what my wood burner was chucking out 😬
@@corower Yep, I have one of those. My phone sets it off too when I make calls within a few metres.
I once spent almost 2000 dollars on a telaire co2 detector for the routine testing of air conditions in an agricultural facility, quite the unit it was so accurate I couldn’t even breathe while testing lol
My parents have an air filter/ionizer that automatically ramps up fan speed based on alcohol levels. Hilarious!
A number of air purifiers have VOC sensors. Could be that
We have quite a few Winix air cleaners and their sensors are rather sensitive to farts. Needless to say, these have been a source of endless amusement. No way someone is getting away with farting in the house without getting caught.
@@grayrabbit2211 and now I need to find one or ten of those to strategically place where my puppy sits. 🤔
@@1973retrorabbit haha
@@grayrabbit2211 i am dying now 🤣🤣
Hi clive, thank you for the video. I happen to work at a company that produces various gas sensors. It is quite common for manufacturers of cheap devices like this to use metal oxide sensors to determine a so called "CO2 equivalent" reading. The sensor actually measures the amount of volatile organic compounds (VOC) in the air and as long as the sole source of both VOC and CO2 is people, there is a quite good relationship between the two. Of course this doesn't work in environment with artificial VOCs. The reason for doing this is that metal oxide sensors are much cheaper than NDIR or PA Sensors normally used to detect CO2. Of course I agree, that the marketing for this device is not completely honest, it does not measure CO2, it measures VOC and calculates a CO2 equivalent reading, as a total VOC reading is not very easy to grasp for the end used. We actually discourage the usage of "CO2 equivalent" readings in favour of an "air quality index" which just tells the end user if it would be a good idea to open a window.
I am surprised you haven't campaigned to safety authorities to get these things banned
Anything which can miss high levels of CO2/CO (false negatives) whilst also giving alarms (false positives) when they're not present will fool consumers into thinking they're working properly
Yes, some of these are sold as monitoring CO as well as CO2
Me thinks that Clive had quite a few "test" glasses of spirits for this video :)
I may have consumed an entire bottle of wine.
@@bigclivedotcom And still cleverer than the rest of us... 😎
@@bigclivedotcom Oh, the sacrifices you make for the sake science. We are all so thankful for your sacrifices so we can be better educated.
...all these re-takes! Sheesh! ;-)
Had to experiment to determine which liquid demonstrated the best, wine/spirits/beer etc *hic*
Years ago at a remote scottish BR driver depot, to save money the train crew supervisor was replaced with a breatherliser machine fitted. This was to save money. A driver booked on who had fish and chips with pickled onions for lunch and the machine mis-read vinegar for alcohol and wouldn't book the driver on. So the next day all late turn drivers had fish and chips and pickled onions for lunch. Within a fortnight, it had been ripped out and the TCS was re-instated. This was reported in Rail News in the 1980s.
Thanks for the video Clive! After testing mine with 99% Isopropanol (no effect), I decided to take a closer look at it. The internals look completely different. Different PCB, different Display. It seems to have a MH-Z19E CO2 Sensor, that is installed on a separate PCB. It's display has a flat ribbon cable and uses a STM32F103 processor. The Battery(1200mAh - floating in the case) and the DHT-11 sensor were included though. 😃 From the looks of it, it could be repurposed for other things too. It would just need different code for the MCU.
Wow, can you give a link to the product? Sounds like a good device for a DIY project!
Co2 sensors are common because Asian countries (at least Japan)started recommending /mandating that all public venues have them at the start of the covid pandemic, in order to show sufficient ventilation in a crowded room. I believe the suggested max level was around 1000. They are still in place everywhere
Clive, I used to repair Co2 meters used in greenhouses, they were an old design, an heat source at one end of a tube and photo cells at the other end, it works with air sample pumped in the tube and measures how much Co2 that absorbed the infrared
I have been designing and installing such devices were it is very important that they do correct work. It is so irresponsible and potentially dangerous to put these on the market. Great work Clive!! Keep it up!
Especially given a similar design was sent out to schools in the UK for use in classrooms to help them balance disease prevention with heating requirements given how expensive energy is at the moment. That's designed to a spec though and only has 3 colours, lighting up one at a time from 400-800, 800-1500, and 1500-5000, to match previous models that had been produced from the Chinese factories that Rexel (who got the government contract for the CO2 monitors) had contracted out to.
@@itskdog did they work
@@tylern6420 as far as I can tell these are working. The numbers for with previous models we received in the first batch in 2021.
@@itskdog must be a proper sensor then
CO2 is good to measure as a proxy for air/ventilation quality, especially in terms of trying to inhibit the spread of infectious diseases, alongside how high CO2 levels tend to make people feel pretty sleepy/crappy. Had long wondered if the super cheap CO2 sensors I'd seen on sale were just VOC sensors, as actual CO2 sensor modules themselves are usually at least 70% or more of the price of them, big part of why I ended up putting some together myself. At least this way I know with certainty I'm actually measuring CO2 itself.
These tin oxide sensors *can* be surprisingly clever. As you said, the gas in question is stealing oxygen from the tin oxide making it more conductive. The sensor can't identify specific gasses but depending on the power of the heater it can narrow them down. A "low temperature" sensor will only respond to very reactive gasses like formaldehyde and carbon monoxide. "Medium temperature" will also respond to alcohols and ethers and "high temperature" will respond to any gas or vapor that can be oxidized including things like butane and mineral spirits. With multiple sensors it is possible to program a "smart sensor" that can distinguish, for example, ethanol from propane. But no amount of clever programming is going to detect CO2 as it doesn't react with tin oxide.
I notice the care you take with the utterance of "nic...o...tine" to avoid upsetting the mechanical censors. You could always tell them you were referring to that notorious supervillain from early 80s public service comics, Nick O'Teen.
I often refer to my devices as a "Personal Electronic 'Nickelteen' Inhalation System". Though speaking that as an acronym may also trigger a censor-bot.
@@erinw6120 Right....
Clive, I bought one looking like this for about €40 during the lockdown and it works perfectly well. I have tested it in CO2 atmospheres in our university chemistry dept and it gives a fairly accurate CO2 reading. Put a cloth over your head and breath inside it with the sensor for a minute or two and you should see the CO2 level rising to 1000+ ppm. Take it into the toilets and you will see the HCHO (formaldehyde) and the TVOC (total organic volatiles) go high, due to the cleaning materials used. The CO2 will go up also as the sensor is not specific to CO2 only. I am guessing your one was either a cheap clone or else missing a sensor - faulty manufacture and/or QC. "One swallow does not a summer make!"
love it, seems to be loads of sellers selling basically identical models but with ranging prices
That's always the case, you can always pay double for random Chinesium gadgets on ebay if you like. Unless there's something you know is actually expensive in there (e.g. special gas sensors), I usually aim for the cheapest one I can find for stuff like this. Only exception being if the manufacturer is known and there are known fakes/clones out there that don't work as well, then buy from the source/authorized sellers.
There do exist eCO2 sensors, such as the CCS811, which use a TVOC sensor and some maths to estimate the CO2 in the room. Of course, if you just want an indoor air quality score, TVOC is a perfect metric anyway.
Not in my experience with the new Sensibo air quality monitor vs an actual CO2 sensor. We burn candles indoors and the eCO2 sensor is useless for that use case. I returned the Sensibo.
@@mrtechie6810 Well technically burning a candle does taint your air quality by the fact that you're burning something and releasing micro particulate matter into the air in your internally monitored space.
@@longnamedude3947 not enough to matter, apparently. The CO2 levels increased from 400 to over 1000ppm, but the TVOC and PM2.5 sensors in the Sensibo did not measure anything significant.
@@mrtechie6810 Well that's based on current health guidelines, and having seen the various changes globally by regulators on what the maximum level of various particulate matter should be in the air for safe and healthy living I wouldn't be surprised if a lower level for total volume of particulate matter per m² changes in the following 10-Years as new research into things unveils hidden dangers we may not have previously been aware of.
@@longnamedude3947 No kidding, people once thought burning coal gas inside for light was a brilliant idea.
This is really interesting. My Uni put two of these units in one of our computer labs alongside a UV purifier, which I think was part of a test to see whether the HVAC was actually filtering the air. They were slightly different as they were in a white case, the beeping tone was faster and I believe they charged using Micro USB; other than that, exactly the same, including the layout of the display. It's interesting to think that they might never have been accurate at all. They did sound the alarm rather frequently throughout the day but the only potential sources of alcohol would've been hand gel or cleaning wipes but we never used either that excessively so maybe they were genuine or possibly detecting something else completely. The purifier they were using sensed PM2.5 and that never had to increase power to clean the air so they came to the conclusion that the air was being cleaned already and removed it and the sensors 6 months later
I got one that has a similar UI from amazon (the INKBIRD). It claims to be an NDIR measurement and it definitely seems to work. In my room after I sit for a while it can get up to 1500, but open the window and it goes back down to 600 ish. Set it on the top of a seltzer bottle and it maxes out.
I looked up a lot of information about these things before buying an Aranet 4 CO2 sensor which actually does contain a proper NDIR sensor. Basically all the cheap CO2 meters do the same as the one choice took assist because measuring CO2 actually requires more expensive components.
The reason your vape set it off is that many food flavorings have ethyl alcohol in them as an emulsifier. Thanks for the research!
I went through three CO2 meters from Amazon that worked properly for about two weeks and then "soft failed" where they indicated a safe atmosphere even though it was toxic. I gave an objective but negative review after the third unit failed under warranty. The OEM reached out to me and is sending me a redesigned unit for testing. The bottom line is that there are similar looking units that actually have fairly respectable manufacturers taking responsibility for the product. I have a winery and need affordable sensor in some spaces that have an audible alarm and can be checked over the wifi network. The units that failed had all those functions, but did not last...
If I buy a CO2 meter I want it to measure CO2, not alcohol. CO2 meters are good to measure lack of ventilation. You are not going to detect this with an alcohol detector unless there is a drinking party going on.
Good to see that someone exposes this problem.
I worked at Microsoft in a building they rented back in the 1990’s. They changed the cubicles to only 6’x6’. Everyone got headaches after 3pm. Back then it was expensive to test co2 but after months we got them to test it. The level was above 2000ppm. They upgraded the hvac system fresh air and our headaches went away.
Great tear down! My MIL had a CO alarm with a built in methane alarm. Every time she mopped the floors it went off. We figured out it was alcohol in the cleaner that set it off. Probably a similar sensor. It got on her nerves and she chucked it.
That latching power supply reminds me of what you had to do before microprocessors/controllers had low-power and sleep states.
One such design I was involved with back in the late 70s involved used a Z80. In order to power it down when not doing anything the trigger inputs went to a CMOS XOR gate, the output of which switched on power to the Z80. The other input of the XOR was from a CMOS latch controlled by the Z80. Sequence was a change of input switched on the power to the Z80, Z80 held on the power, did its thing, set the latch to the same state as the input then killed its power.
Having now looked it up, it was a 6802 with a 6821 PIA and the last update was in 1983.
I think a microprocessor "keeping its own power button pressed" is still the best solution for battery life, because you can get truly zero current when turned off. A sleeping low-power micro might drain the battery in e.g. 3-6 months of non-use, whereas a disconnected battery stays full for many years (especially non-rechargeable cells).
It's silly that adding a transistor used to cost money, but these days they can be cheaper than the cost of the bean-counting and re-engineering required to make it work without one. Though that doesn't stop bean-counters from demanding the removal 😆
@@renxula FWIW I've got a bit of test kit I built back in 2013 using an ATtiny13A which goes into deep power down when not in use. Iq is less than 1uA and it still works fine on its original two AA cells. As they're now in the danger of leaking zone I might swap them for a 123A lithium cell.
If you are living in a house with 4 walls and a roof the co2 levels will rise quite fast with 4 people or more, no need to hermetically seal your house, our living room goes up to about 1200 after 2 hours with 4 people, this is not dangerous but it is above the recommended limit here (1000)
Glycerol is an alcohol, so I guess it depends on the specificity of the sensor
I come across C02 monitors at work as a Supermarket Refrigeration Engineer, either CBISS or CPC.
They can be configured for HFC or C02 refrigerant. They are networked to RDM panels, so alarm along with the fridges, they're usually set for 3000, 5000 & 15000 ppm, with c02.
They take a baseline reading, then compare that with readings from every channel throughout the store. They're not cheap £4000 to £5000 if I recall. We also tend to have a few issues with them, pumps, IR sensor bench or PCB failure
The sensors reaction can be explained by the cross sensitivity of these sensors. For my work I have a BW GasAlert personal gas monitor and it measures oxygen, CO, H2S and LEL. The CO (not CO2) sensor is extremely sensitive to alcohol. I discovered that when I had hand disinfectant on my hands and brushed the sensor with my hand. The thing went through the roof.
The CO sensor is also cross sensitive to hydrogen, hold it close to the vent of a charging lead acid battery and it reacts as well.
In this case, I wonder why co detectors are so expensive at hardware stores, if a cheap ebay device does the same thing
@@treadless_co reliability is a thing as well. I rather have a properly tested device than a random eBay special.
I think a portable CO2 metre is very handy providing it is good quality. If you go into a room when there's a meeting, sometimes it's like being on a stranded submarine. Having a CO2 metre prevents any arguement about opening doors and windows, particularly in winter. Also it's very interesting if you sleep again in winter with all the windows and doors shut good to know that you're not getting high CO2 levels in your bedroom.
It's not a fake. The description of these units on Amazon (eg) states correctly that the detection method is "TVOC", Total Volatile Organic Compounds. In other words they're designed to detect levels of anthropogenic VOCs which are generally produced alongside CO2 in human activity such as respiration. So the level of VOCs in the air inside a building where human activity is taking place is an indirect indicator of CO2 levels. VOC detection is a lot cheaper than direct CO2 detection allowing these units to be produced for a fraction of the cost, but yes the downside is that they are easily fooled by introduction of VOCs without CO2, or vice versa.
Just because they're using weasel wording doesn't mean that they're not fake in terms of getting consumers to trust them when they shouldn't
I've got a CO2 meter here at my home as a detector for when to open the window (it also contains a hygrometer). On the back it says "NDIR", so I hope that it is not faking the values. I like these devices, since you mostly don't recognize your own smell. I guess that the sensors aren't calibrated very well, but they fulfill their purpose.
Quite interesting that you got the result you did. I have a very similar looking model at home that I paid decent money for from a reputable store. Mine has the exact same screen, however it has a white plastic box, not a black one. Looks like it might have more vents on the sides as well. If I blow on the back of mine, it jumps up to 2000+, but not an instant 5000 the way you see on yours.
I did a little test of rubbing some isopropyl alcohol on my hands the same way you did and then providing the fumes to the sensor and it didn't move at all.
It would appear that not all Chinese made CO2 meters are equal.
I was worried that mine was fake after seeing this videos, but luckily mine has a white background and was also bought from a reputable store, glad to know that I most likely wasn't scammed haha
I'm going to have to try the alcohol test at work. We have very similar looking things and they are always going off with 1500ppm readings. Even when it's sitting right next to an open window in the hallway. Now I wonder if it's the ritual hand sanitizing setting it off.
So a VOC sensor instead of a CO2 sensor inside? I guess VOC was cheaper...
(Also, the demand for CO2 sensors is because CO2 is a reasonable indirect measurement of ventilation in a room which, y'know, kinda important during a pandemic with an airborne virus)
not exactly, those petroleum products that didn't trigger the sensors are VOCs.
yes VOC is much cheaper
Actually not just pandemic useful, our ability to concentrate and think drops too as the CO2 concentration goes up. So pretty important in general even at home, but I'd expect employers to ideally want the employees they pay to function well. Same with schools that try to teach children, so many of them sitting in one room seems like a great way to quickly get the CO2 above the 1200-1500 ppm where things go downhill quickly if there's insufficient mechanical ventilation while the windows are closed.
It'd take a lot more than the usual 1200 ppm threshold for "bad air" to make it actually acutely dangerous but a few real sensors with useful displays probably wouldn't hurt to remind people to do the right thing. Ideally you'd want the ventilation system of the building to measure the CO2 levels in the room though and adjust what it does as needed, that way you're wasting less energy on extra heating/cooling during low occupancy periods and can prevent the "I don't want to hear the noise/feel the moving air" humans from turning it off.
I did get one actual CO2 sensor myself and it's a useful reminder at home, if I keep the doors between rooms open on most days it stays nicely below 800 ppm or just above with just me and my two cats. 3 or more people for 30 minutes or longer will quickly turn things red, it's a good reminder. But oddly enough there are days without visitors when it does trend towards over 1200, must be the wind direction and force affecting normal passive air exchange in this old house. Closing a door to keep cats away from electronics components and soldering irons also raises it quickly, indoor exercise even faster. I am looking forward to exposing the sensor to some other gases now though to see if it triggers on any other ones I can easily produce.
@@extrastuff9463 With my NDIR based CO2 detector when the oven and hob are on for a long time downstairs the CO2 upstairs seems to rise significantly could a cooker be doing it?
@@cnafyi Honestly no idea, since you mention CO2 and the oven I assume that one is gas powered and not electric? And while running either or both is that with the some kind of mechanical extraction to vented to the outside being on preferably near the hob? (traditionally above it here where I live). If that's done and doors to hallway and upstairs stay closed I'd expect the impact to be minimal but I never really measured it.
Could try measuring it in the near future, but I have a gas hob and one slowly heating old traditional full size electric oven + combi microwave with a functional small convection oven that heats up quickly. So much less CO2 being released into the room along with a noisy but effective extraction fan above it. And maybe measure it again when it's warmer weather when I often leave all doors to upstairs open so the cats can roam freely, currently not done to reduce the heating bill.
My kitchen, living room and bedroom are all downstairs. Upstairs is only for my storage and hobby room, treadmill and other exercise equipment lives there. Measured using that with closed door and window a few times, it gets the CO2 concentration above 2000 quickly given that it's a tiny room. Leaving the front door downstairs open and partially opening the upstairs window solves that problem though.
It could be a VOC (volatile organic carbon) detector. Those are often in packages with humidity and temperature sensors. You can probably also detect other vapours such as acetone, acetic acid (vinegar), perfume etc.
It probably does not react to butane and similiar alkanes because they are much less reactive.
Volatile Organic Compound, not carbon. VOCs have carbon in them, but they're just chemicals with low boiling points, thus they easily transition to gases (which is the definition of volatile).
If you have an actual CO2 meter, it's a pretty good proxy for how well ventilated the area is. And it's also pretty well correlated with your risk of catching airborne illnesses from other people in the room.
I just looked at this board and the real sensor 2 days ago on Ali. I made a real CO2 and PPM2.5 displaying thing a few years ago and now wanted to make a few more. The "real" sensor this was made for was a MH-ZH19 NDIR Sensor - you can grab one for about 17EUR.
Good to know 👍🏻
@@sorphin Ugh - too late for me then - save yourself!
although some could be straightforward and easy to make, sensors science is a really interesting field, it covers lots of knowledge in chemistry, physics and maths obviously and the technical challenges of making them at a large scale! fascinating! Thanks Clive for the great effort of reverse engineering these things up!!
To answer your question, measuring co2 in a room can be very useful information to a certain type of indoor plant grower
I truly admire the creativity creators employ to bypass the YT demons. I also hate the demons.
Change the 10K resistor in series with the sensor, to change the scale down of the reading ( so that it does not over range ), then use it for a party drunkeness meter?
Little SMT trimmer, so you have a certain level of calibration.
Fun and infovideo as always Clive!
I have two of these sensors, one CO2 and one fine particle, both in same housing you show, only with Micro-USB charging.
Both work fine, and the CO2 sensor goes to 400 for a period of time sometimes, in fresh outside air just over 430 ppm and inside depending on people in the room and ventilation. Similar values as a professional one.
The fine particle one is also quite good, detects when the fireplace is (not often) lit, and has an internal small fan for airflow.
Will test the cross sensibility with Alcohol 😉🍺🍷🥃
One thing to note about CO2 sensors in general, they're quite slow to respond. The one I'm using in a project is from Sensirion (the SCD40) and it can only put out a reading every few seconds, and that reading won't be all the way to the actual current value, generally. So even if this was a legitimate product and not using a temp-humidity only it might not respond well to a quick blast with the Sodastream, since the CO2 would largely dissipate before it the sensor managed to update fully.
As far as I remember, CO2 sensor values need to be corrected according to the ambient temperature and humidity. So adding a sensor for them is reasonable.
It would probably be better to use something more accurate than a DHT11, though. At least if they had used a real CO2 sensor...
My NDIR CO2 detector responds almost immediately to a strong source of CO2 such as my breath. A SodaStream blast has 20x the CO2 concentration of breath, so any true CO2 detector would quickly spike in response to that. But it can take ~30 seconds for the reading to stabilize, as the gas needs to diffuse across a membrane into the detection chamber.
I spat out my drink when you "enhanced" the photo.
It's a CO sensor. CO is a reducing agent and it gets catalyzed on a piece of platinum wire. It's the same sort of sensor as the alcohol ones but calibrated and produced differently.
As for what they react to, most alcohols, I would say esters are a safe bet too, like ethyl acetate, acetone, hydrogen, and ammonia. Second to last blows up on contact, last one turns into the brown unwanted gas.
Interestingly the Scottish building regulators now seem to require CO2 meters to be installed in the main bedroom of new build properties where there is less than a certain level of airflow in the room, seen them in several different properties built in the last few years.
*Hermetically sealed building* An office block I worked was being refurbished. Idiot in charge put in air con with no fresh air supply, and then *sealed all the windows* . People were falling asleep, complaining of headaches etc. Temp in HR had a CO2 meter (they were an environmental health officer before) went round and found high CO2. So they sacked her, and had meeting were said idiot stated "well we aren't opening the windows!"
When people complain about where they work I always trump them with "did they take away air from you"
The year before They refurbished the heating on one floor, but didn't turn it on (ceiling ac units) , people were seating in sleeping bags at their desks with wooly hats and gloves!. Our floor was baking, I used to go down to them in just a shirt and complain about the heat to wind them up.
In the USA, for decades mechanical codes have required a fresh air intake in commercial buildings. Also required for residential houses starting sometime in the last 10 years or so, if the house is too "tight" as measured with a blower door test. (I think most builders just plan to make the house tight and install a ventilation controller to pull outside air in--if the house isn't tight enough it will fail the blower door test).
@@brianleeper5737 did they have a "don't put an idiot in charge of the building refurb" rule as well.
@@yesihavereadit Sort of--most jurisdictions require an inspection. If the building doesn't have the required ventilation it will fail the inspection, and whoever did the work will have to make the corrections and get it re-inspected. So it's well known that having an idiot in charge of the work is a great way to fail the inspection and have to do it over. Also, the inspector, at least around here, doesn't always arrive at the scheduled time, because some inspections take longer than the 1 hour allotted. So if you have to have a re-inspection that can be 2 or more additional hours wasted waiting around for the inspector. Bottom line: Failing an inspection is wasted time and money.
could have given toast to davey who found the guase prevented explosions in mines. great teardown and explaination as always
The co2 reading is directly related to virus levels in the room. If there is someone with covid or the flue in a room and that rooms co2 level goes to 1200 ppm then there is not enough fresh air intake and virus levels in the air are also beginning to rise.
I have used a co2 detector on vacations and at big parties. Almost every bus getting to excursions had co2 levels above 1200 ppm. So I put on an n95 mask.
Thanksgiving at my house is 25 people. Co2 gets to 1800ppm if I don’t have the circulating fan on. I can actually control the enthusiasm of conversation by playing with the co2. Allow it to go above 1500ppm and the room gets quiet. Bring it down to 800 ppm and people start talking again. It’s kind of funny to play with.
The idea here is actually good given that the device measures CO2 properly. I actually sometimes had a little problem with CO2 in my old apartment. Living room was maybe 20 sqm. At 2,5m height it's 50 cubic meters. Let's say that we have 8 people there and the room is sealed (maybe it's a cold winter or very hot summer and you run a lot of AC in closed loop so you want to save on air exchange). In just an hour you will reach 1% of CO2 concentration which already feels stuffy and not fresh. If you'd continue, after 8 hour party in such sealed room it will be over 6%. Very high and dangerous (the actual limit for workplaces is 1% for 8 hours or 3% for 15 minutes). Now it seems unrealistic but it's enough that you don't have enough ventilation and you may have problems because of this. The problem is that although alcohol level in the air may reflect how stale the air is on the party, it's not giving us much. In my office we have booths used for short meetings. Those are roughly 3x3 meters, so around 40 cubic meters. You have a meeting with 6 people in it. After just half an hour it's over 0.6% which is already not comfortable and affects how people feel, in an hour it will exceed the allowed concentration. Despite having some sort of ventilation, those don't have enough airflow and are soundproof, so they are actually sealed from the open space too. It's a bad design and it can only be used for up to 15 minute meetings after which you need to leave the room open to vent it out. If you have a few meetings in there one after another, people don't even want to get there as they start feeling bad after a few minutes. If only they would have a working CO2 meter in there.
So glad I didn't buy that one. It's cheap. But the one I got had more review and a better rating. Also, a non alcoholic exhalation with raise the numbers. Cooking on my gas stove without the range hood venting also raises the numbers. One time making fig jam I had the large burners going full throttle and it set off the sensor on the other side of the house. It is good to have a co2 sensor. I now use the vents and open the windows more often. I have the Forensics Detectors FD-CO2000.
Interesting...I have one of those bought from Amazon Canada, and it does detect CO2. If I breath into it, the CO2 reading jumps dramatically (1,200 to 2,000), and then slowly returns to normal (high 300s, low 400s). When I tested, I had no alcohol or nor do I vap.
I bought it since I wondered if I had a exhaust leak on my Subaru, and I put it onto a car window mount, and I was driving along in winter, and suddenly it read over 4000-5000, and I had noticed that I was getting sleepy. So I opened the window and the count dropped slowly back to normal. And I do have an exhaust leak.
I was considering this very same 'monitor' from amazon. There are a number of them but they all have the same 400 floor value and I could not understand why. Now I do. Thanks for the comprehensive teardown and the laugh at the alcohol sensor called CO2.
True CO2 detectors also have a floor of around 400 ppm, because that is the CO2 concentration of clean outdoor air.
Stuff like this will always use a segmented display as they are much cheaper, need much less processor power and have much lower power consumption.
That is so funny! It's a party alarm. I seem to remember a song about that from a few years back!
The same sensors are being used in various Tuya enabled devices sold as CO2 sensors. I got 2 different ones, they also go wild near isopropyl alcohol. We were making mussels with white whine, when the bottle was standing open next to the sensor, it started to trip the alarm “GAS detected, evacuate immediately”, while we were cooking electric :)
6:27. "There's something really annoying about this." I watched the next scene a dozen times, at least. I still don't understand most of what you said. But every time, I laugh my a** off at your delivery. Bravo!
Damn, I bought a slightly similar design from Techno line and it turned out to be the same fake CO2 reader. Thanks for the video.
I got an identical-looking model recently. Testing it, it definitely reacts to alcohol (I got extremely mad when it worked), but it reacts to the breath of extremely sober people too! So it does seem to detect (something that at least approximates to) CO2.
Just because it reacts to breath doesn't mean it reacts to CO2. Breath contains trace amounts of alcohols and formaldehyde that the device may be reacting to. Test it with an actual CO2 source.
This is likely used for indoor grow rooms where higher co2 levels benefit plants because that is their food. Temp and Humidity are other typical grow parameters that are monitored.
I've used uCs to run multi-digit 7-seg LCDs directly. The segs are brought out separately, and one common lead. You alternate all signals between 30 to 50Hz. ON segs are out of phase, and OFF segs are in-phase, relative to the common. If the uC stalls, you just polarized and wrecked the LCD.
Of course, the designer of this unit would take care to use the uC's watchdog timer, to prevent this from happening, just as he was careful enough to buy the "correct" CO2 sensor ... yeah !
Just got given a load of these courtesy of some government department, nice long type C cable, USB charger looks nice. Reads twice as high as the old ones we had. Humidity reads around the same
Mine doesnt beep :((((
I have a CO2 sensor that's _almost_ identical but with a whole bunch of very tiny differences:
- "PPM" label is less bold and the "CO2" label is 3 characters of equal size and position
- the digital display stays centered and does not employ a leading zero
- the level dial has a gradient outline surrounding the 4 intensity marks
- the battery indicator has no opening on the right and the fill meter inside is continuous
- temp symbol is a thin line figure representing a thermometer, with scale lines across it (instead of an outline-plus-fluid depiction)
- humidity and temp numbers are in a bolder and smoother sans-serif font
- there are no "temp" or "hume?" labels, just symbols
- the side perforations in the body are smaller, simpler, and more numerous
- and most substantially, the port is micro USB
Perhaps most importantly, however, I can easily max it out (at 6,000 PPM) by slowly exhaling into it, and it is completely indifferent to alcohol. It also roughly agrees with various other CO2 sensors I have. I guess mine is the real deal.
Technology Connection recently posted a video showing that his gas stove caused CO2 levels to be surprisingly high in his poorly-ventilated apartment
not co2.....particles........PPM....
@@roybarton9617 PPM is a measure of concentration; like percentage but at a smaller scale. It is ubiquitously used for expressing CO2 concentrations.
So if TCs air quality detector was decent and not fake like in this video, then yes CO2.
You unkowlinly just answered an issue I have with my new nightcore headlamp. It uses usb c but does not charge with smart pd units. They must have left out those resistors.
I almost bought this device a week ago. I bought a CO2 meter, ended up with the Airthings View Plus, to track CO2 levels while I sleep. My bedroom occasionally reached 1500ppm while I slept, and after a few data points, the nights where it reached that high correlated to days that I woke up feeling lethargic and having an “off day.” Tracked it down to A) poor air circulation in my house and B) insufficient air flow to my furnace. I rent and the previous tenants stuffed rags in the air supply vents since they allowed cold outside air straight into the basement.
Sleeping with the bedroom door open and setting the thermostat to turn on the air handler 15 mins/hour, regardless of turning on the heat, seems to have mitigated this issue.
Of note, I believe the Ecobee Premium uses this method of indirect CO2 sensing. I think the proper NDIR sensors are like $50 for the module itself, hence cutting corners for cheaper sensing devices.
A 400-ppm increase (so, from 400ish to 800) in CO2 concentrations can lead to a 50% decrease in complex strategic thinking, that's why they measure it.
My guess is that the engineer who came up work your device was in a high CO2 environment
A similar model was sent to schools last year, but they are NIDR sensors and only have 3 colours not 4 to match the previous monitors that were sent out in earlier batches.
Assuming the firmware is similar, your speculation about calibration is close. The instruction booklet we received said that before first use you were supposed to take it outside, leave it for 5 mins (as NIDR sensors seem to take 5 mins to get an accurate reading), and then quickly press the power button 3 times to calibrate it. It probably read 400 when you were outdoors as that's the lowest number it can display.
I just bought a variation on this and it detects alcohol, it detects natural gas from our cooker and it also goes off after a particularly prolific fart. If I use the toaster it goes off and the levels go higher when we cook (either in the air-fryer or the gas cooker).
Mine purports to detect TVOC, CO₂ and HCHO (formaldehyde).
Brilliant even good for the display I wonder if you could get a proper sensor and putting it in ?
Thanks Clive
Inspired by this teardown, I pulled apart an almost identical detector I had (labelled H8 Plus, not H8). Same thing- a no-id markings VOC detector unit. Cunning thing was that at several places on the circuit board, there were screen-printed labels 'CO2 SENSOR'. Suggests that manufacturers have felt the need to up their game with an increased level of deception.
The only use I can think of for a device like this is for greenhouses which pump CO2 into the growing area on a schedule to feed the plants. Usually this coincides with disabling the ventilation, and having a hard reading of the CO2 values as they fluctuate with the high plant load will give you an idea of the health of your crop. A relatively new hydroponic tomato farm near me does this.
Interestingly, I have a CO2 detector that looks identical, including the label, except the case is white, and I didn't buy it from ebay. It seems to actually detect CO2 spikes when I breathe on it at least (without having had any alcohol), so it looks like the one you have is a fake based on a model that (probably) actually works.
I got it because I was concerned about CO2 levels from having a gas stove/oven and furnace, but turns out my house is old enough that it's quite leaky and not a problem.
Thank you Drunk Clive, that was interesting. I have quite a lot of different snsors, I might get one of these and see how they perform when I swap them over.
A distributor or manufacturer of one of those monitors contacted me to do a review on my channel. I said sure but when I mentioned in my company I have various gas monitors so it would be great to give it a full test. All of a sudden they had filled their quota for reviewers and didn't need me any longer. 🤣
I can personally say that, having a reputable detector, my indoor bedroom CO2 levels range from 800-1200, which I am none too happy about.
Once when I had a guest over it spiked over 2000 and I found out it had a default alarm setting.
VOC sensors on a PCB can be bought for a fiver and linked to say an Ardunino. I am going to use one to boost my all house ventilation unit when it detects cooking etc. VOC is a better measure of such than CO2. It does provide an eCO2 reading too but I ignore that. Also has a humidity sensor to detect say showers.
The sensitivity is amazing. Move your hand near it and the VOC reading goes up within a couple of seconds.
i am sad it did not get endorsement, an unit like that would a great tool for us indoor gardeners.
48-pin PIC (18F5xxx) chips seem to have power directly opposite on pins 6,7, 31,30 whilst the ATmega809 uses 14,15, 28,29, 42,43, which may help with ID.
Where I work, we purchased some devices that look identical to this one indicate where we might require better ventilation during post-lockdown restarting of meetings in our rooms.
Ours very much appear to detect co2 rather than alcohol though, due to the fact that our site is a church and therefore consumption of alcohol is restricted to limited and specific occasions. 😉
Worked with Sensidyne Flammable gas detectors years ago, operated with a wheatstone bridge, catalytic bead resistance circuit housed in a sintered cap, gases methane, hydrogen, ethers and alcohols, all detected using this type of sensor.
The chip part number is likely etched off because, in this time of grey market ICs, reselling is common. Many contracts for OEMs will state that they cannot resell parts. Part manufacturers keep track of where batch numbers are sent, and thus know who the scalpers and second sellers are.
In an enclosed space, CO2 levels are an excellent proxy for viral transmission risk, so they have been used to regulate ventilation in enclosed spaces where people congregate. Our restaurant at work has windows hooked up to a CO2 monitor, so as soon a threshold is reached, all of the windows open, then close again when another threshold is reached, after the CO2 level drops.
This automation allowed the 2m separation restrictions to be relaxed earlier than most people would have been comfortable with otherwise.
It's worth noting that there have been studies that show that poorly ventilated offices have high enough co2 levels to cause significant decreases in ability to concentrate
I don’t think it was one person/company involved. The sensor supplier was probably scamming the company making the full devices. like „oh you want a cheaper co2 sensor? sure we built one…“