AZDelivery MQ-135 Air Quality Gas Smoke Detection Sensor Module compatible with Arduino and Raspberry Pi including E-Book!

These work weii and within spec.

Very good

The soldering was a tad bit loose & needed constant adjusting to get any output from the sensor itself. But worked fine after a bit of fiddling around

I think AZ delivery products rock they just work

Only used the analogue output but output to arduino and read the value. Simple 5v supply but seem to work ok on 3.3v too Calibration is still a work in progress

It’s a bit vague what this actually detects (although the datasheet lists all the different gasses/vapours), it’s not just organic molecules, it’s not just acidic gases or alkaline gasses, it’s just kind of a weird mix of unrelated things. I would say this is a great cheap sensor for VOCs (e.g. in a workshop) but the fact it picks up atmospheric CO2 and NOx too makes it kind of pointless. It just tells you there’s some amount of atmosphere around. If you used this in only a controlled environment where no more than one detectable gas could be present, then it’s great…but no one buying a cheap sensor has that use-case. So, it’s fun to play with and see that numbers go up when you use alcohol/paint/ammonia/breathe nearby, but for the home-gamer that’s about it.

Can print pretty graphs using this sensor as an input.

After testing and leaving these devices to 'settle down', the readings between the devices whilst located next to each other vary so much that I just can't rely on them, they also fluctuate quite a bit which was a surprise too. I've literally got two of these side by side and one is nearly (!) double the value (analogue) to the other (swapped ports to confirm it wasn't my MCU). I can calibrate these which I may do (or get a different supplier in the hope they are more aligned), but not a great initial impression. I did test with some chemicals nearby and they did react very quickly, hence the 3 stars.

funziona bene. i pin sono sani. è sia digitale che analogico ma se volete semplificarvi la vita, prendere dei sensori completamente digitali, altrimenti i valori in output andranno lavorati. Errore mio di inesperienza, ma funziona bene.

Der Sensor reagiert auf verschiedene Gase (Ammoniak (NH₃), Alkohol, Benzol, Rauch, Kohlendioxid (CO₂), Stickoxide (NOx), Rauch etc.), aber er liefert nur einen Analogwert. Folglich kann man nicht genau bestimmen, worauf er im Detail reagiert. Wichtig auch vor der ersten Verwendung die "Einbrennzeit" von 24-48 Stunden zu beachten - die Werte sind ansonsten nicht reproduzierbar. Auch zu beachten: er zieht relativ viel Strom für sein Heizelement - je nachdem sind separate 5V notwendig. Ausserdem: nach dem Einschalten braucht er einige Zeit (etwa 10 Minuten) bis er halbwegs zuverlässige Werte liefert. Er ist also in der Handhabung etwas schwierig, aber dennoch ein guter Sensor um kritische Änderungen der Luftqualität zu überwachen. Recht nützlich : die Library MQUnifiedsensor. Da der Sensor genau tut was er soll (und qualitativ gut verarbeitet scheint), muss ich die volle Punktzahl geben.

They should use better package. Dont know whether it affects the way it operates.

goet tegebruiken maar wel gevoelig dus kijk 2 keer of hij goet is aan gesloten

Pour détection co2 et fumée avec arduino . Impeccable , fait le job.