Hello guys! I'm new to this community and I'm hoping for the best in learning Arduino most especially in relation to the Internet of Things (IoT).
But anyway, we have our current project for our thesis right now and for the past few weeks I've been bugged by what temperature sensor is best used for our application.
I believe I have researched more than enough but I'm still not comfortable enough just by seeing their specs online. I've looked up to the DS18B20 (TO92 and waterproof), DHTXX (DHT22 and DHT11), SHT15, LM35, TMP36, LM34 and so on but I still can't decide what to use as our final sensor.
What our project needs is:
Accuracy of +/- 0.5°C-0.75°
Fast response to changes in temperature
Cheap
Low cost (around 2-4 dollars. Max of 5 perhaps)
Low power (as much as possible but it may be an optional feature)
I'm sorry the post is too long. I badly need help and no one here could really help us out for our project. Thank you!
The optimum choice would be, from among the list, DS18B20. It is digital (10, 11, 12-bit configurable resolution); output is directly calibrated to temperature; it is supported by Library and Forum Posts/Tutorials.
At least by itself, I don't think a temperature sensor is suitable for a fire alarm. By the time you are detecting an extraordinary temperature increase the fire could be quite severe. You can buy a real smoke detector for a quite reasonable price and then figure out how to hack in the IoT functionality to make it much improved. You can get a usable signal from the buzzer lines with a bit of work.
Of course you shouldn't rely on modified safety equipment unless it's been formally tested but as a supplement to an unmodified smoke detector this can be very useful.
@GolamMostafa
What kind of DS18B20? The TO92 or waterproof type? Have you had any experience regarding its usage? Thank you
@pert
I have a temperature sensor and at the same time, an MQ-02 Gas and smoke sensor. The latter is pretty much used in a lot of projects I've seen online. Although the MQ-06 is also an alternative choice, I don't really know which to choose.
I've also considered buying an actual smoke detector but I'm kind of inexperienced with tinkering on those things. But thanks.
OK, that makes sense to use the temperature sensor as a supplement to the smoke sensor. It's funny because I bought some of those MQ sensors, then after some research decided it would be easier and cheaper to use hacked low end brand name smoke detectors (Kidde i9040 is <$4 w/ free shipping on Amazon) integrated with my home automation system. Once I added up the parts and enclosure for the MQ sensor it was the same price and I feel more confident about the reliability of the Kidde smoke detector.
I tinkered around with the smoke detector board for a while trying to get a signal that was easy to tap into. I ended up deciding the buzzer was the easiest solution. The trick is that it's a passive piezo buzzer so the smoke detector has to send a frequency to it instead of just a constant voltage when the alarm goes off. So to convert that to a constant voltage I could read with the Arduino I used an RC filter of a 1 kOhm resistor and a 1uF capacitor.
I wanted to be able to get an analog reading, which would allow me to set different thresholds. Then I could set a level that would only trigger a notification and another that would trigger the full blown panic alarm. Those thresholds could be set differently for each unit. For example if there are a lot of false alarms in the kitchen and bathroom then you raise the threshold. If there are no false alarms in a bedroom then you lower the threshold there. With my buzzer signal from the standard alarm I'm limited to whatever preset they decided was a happy medium between avoiding false alarms but still remaining sensitive enough to catch a fire in the early stages. I'm sure I could get an analog reading from the smoke detector units if I understood the circuit.
Ahhhh, I see. Believe me, I am also wondering if actual smoke detectors would actually perform better in actual since they're sold as commercialized and branded products, and then there's this sense of guarantee that they're more reliable than the MQ range of gas and smoke sensors. I really don't know which is which until I find out based from the experience I will get from using them. But then we really have limited time and budget and I hope our project in its proposal and actuation would really work out. It's really hard to work things out when you have so many limitations to think about, also considering the fact that there's no hardware expert here to help us out, it's really making me go for a leap of faith. Hahahaha. But I really appreciate your long reply based from experience. Thank you!
