ESP32 #78: MQ Gas sensors

[@davidhopkins]

Thanks for the video but I wish you provided more answers. Did you try running these at 3 volts? Did they work? I’m confused. I hope you list a follow up.

[@TrasteIAm]

It's a bad day! @4:58 "today i have no alcohol in reach" Someone has been hiding all the bottles eh? :D

[@fpt380]

Thank for the video ,but did mq135 can distinguish between types of gases?

[@blogactivities5462]

for Gas Sensor project, do we need Fan for air circulation? if yes, what is your recommendation / Thanks

[@RaadYacu]

Thanks for the video. Were you looking for specific gas detector? But I need this to trigger the ESP and not be on all the time otherwise it would not be possible to operate with battery. ESP32 are good but they consume too much power

[@MrJanulis]

Have you ever considered to use BME 680? It's an amazing set of sensors in one enclosure but might be difficult to get all the readings interpreted right due to Bosh policy to document it. If you will decide to build one - you'll be surprised how fast CO2 level rises in closed spaces - I've tested it in a car and with closed ventilation (recirculation mode) it took just 3 minutes for a CO2 level to rise over 1000ppm! Not surprising that so many sleepy drivers making accidents...

[@jasonmhite]

The BME680 is not a CO2 sensor, it senses VOCs. The equivalent CO2 reading it outputs isn't indicative of the CO2 concentration, it's the equivalent amount of CO2 that would cause the same amount of greenhouse effect as the measured gas. It actually has pretty low sensitivity to CO2, in your car it was probably reacting to carbon monoxide from combustion. Put it next to some rubbing alcohol for instance and suddenly it'll tell you that you have lethal CO2 levels. There's a similar sensor to the MQ ones that is sensitive primarily to CO2 (the MG-811) but it's *much* more expensive ($25-50). There are also optical CO2 sensors but they are also $20+ each.

[@MrJanulis]

No, in a car I've been using iAM from ams.com/eng/Products/Environmental-Sensors/Air-Quality-Sensors/iAM and no, it wasn't from combustion, as we've been driving alone at night so our gases were behind us and none was driving in front of us - so I guess it was two of us who produced this CO2 :) (no farting)

[@jasonmhite]

That's also a VOC sensor, not CO2. The readings are "equivalent CO2" en.wikipedia.org/wiki/Carbon_dioxide_equivalent . I don't know of any handheld actual CO2 sensor under $100.

[@MrJanulis]

Literally, you are right. But should I be concern only on CO2 or VOC as well?

[@jasonmhite]

Both. VOCs are basically a measure of pollution, CO2 is air "freshness."

[@MiG-25IsGOAT]

Probably the biggest disadvantage is that for first-time use you need to leave it on for 24 to 48 hours, and for each use, to leave it on for 20 minutes, which is pretty bad

[@oussamafr6123]

What the kind of gas can measure?

[@shashih9130]

How did you calibrate this sensors?

[@RandomGuy-df1oy]

Do I have to use breadboard and jumper wires for this?

[@bilalslama2098]

hi, can i but buzzer 5v in digital output directly without transistor for amplifier. what is the current in sensor MQ9 digital output pin?? thanks brother

[@sketchbyudit4198]

can we measure co2 level and o2 level from the same sensors?

[@abdelnacer7721]

no,cause it's a detector not an analysor

[@jasonmhite]

I found that the breakout boards I bought for the MQ-135 had the wrong value for the load resistor, which makes them give really erratic readings because it lowers the resolution of the sensor a ton. You may want to check yours and compare against the datasheet values. Most of the MQ sensors have logarithmic responses as well, so you need to look at the log of the voltage. They also depend on temperature and humidity, with a correction factor in the datasheet. The best bet is to leave it outside for a while and record the voltage in clean air, then print out -log(Vmeasured / Vclean). Getting accurate absolute values is virtually impossible even with a calibration reference because almost all of them are sensitive to a variety of gasses with varying sensitivities, so it's impossible to distinguish any particular gas.

[@pcbreflux]

Thanks for sharing your experience.

[@jugnu361]

very useful

[@jimmiofficial6784]

can we measure co2 or o2 lavel with this sensor

[@RandomBo0]

Anyone point me in the direction of a Micropython version of this? I can find one for the ESP8266 but it doesn't work for the ESP32

[@vanesinha95]

did the sensor work with 3.3 V or you used a Volage divider?

[@pcbreflux]

Some of them will work with 3.3V, but check the datasheet. Most will be specified at 5V but will work fine with 3.3V without guarantee.

[@vanesinha95]

@@pcbreflux i will have to taste it the worst thing that could happen is that the sensor wont work if that happens i will have to do a voltage divider. thank you!

[@sivakumarc3853]

How to simulate the esp32?

[@kgcmusic]

how can I connect one of them with any plc?

[@TqSNv9R0iG5Ckxew]

The new $250 Ketonix bluetooth ketone meter is based on a $5 gas sensor. I bet you could make a better device for under $20 with a 3D printer, ePaper, and an ESP32.

[@Kitsu_no_mirai]

do this gas sensor module need to be pre-heat, or it already pre-heat at the factory?

[@pcbreflux]

As fare as I read the comments you need some "burn-in time" for about 3 minutes to get the readings stable but this could differ from sensor to sensor.

[@Kitsu_no_mirai]

So there is no need to burn it in 24 hours?

[@Kitsu_no_mirai]

@@pcbreflux and also does it effect sensitifity or value from reading.

[@Cosmos-2022]

@@Kitsu_no_mirai yes you must.

[@mrigankabandyopadhyay153]

Send code for ARM BASED STM32103C8

[@tranvietlan8832]

I want to find code

[@pcbreflux]

Example code and more info in the description.

[@jedandecko5585]

This is not good preview :) those sensor can do some good measurement if they are calibrated properly. I know that referent values gasses are expensive, but you can go to any measurement station and leave your sensor there, go on their web site and compare values with time tags. It`s that easy and free :) BTW I like your channel, but this is rely low quality stuff from you. Keep up the good work!

[@pcbreflux]

Fair enough, thanks.

[@Magic-Smoke]

We all can plug many sensors into the ESP32 and make them work but they are not useful unless calibrated so why do a video unless you are going to add value?

[@jasonmhite]

Virtually nobody has the tools required to calibrate these sorts of sensors, but they're still good for relative measurements. Don't be such a dick.