I'm doing a project that requires a fast response temperature sensor and I'm drowning in temperature sensors but I really have no clue as to which one to choose. Some of them have some response time info in their datasheet but not nearly all.
I was hoping that someone here would have some experience and might be willing to provide some tips?
I already have the Sensirion SHT11 sensor and it seems to be a little slow for what we want (just to give you some idea of the response time I'm talking about).
I'm not all that familiar with electronic components so if anybody can point out something that might work I'd really appreciate it. The plan is to buy a few different ones and set them up in a test (log the output from each one and compare in a plot to find the right one for us based on response time and accuracy). As I said, response time is important for us as well as consistency (which is actually more important than accuracy). These will be weather measurements so operating temp between -20 - 40 °C would be good and I think accuracy of +- 1 °C would be okay.
StFS:
As I said, response time is important for us as well as consistency (which is actually more important than accuracy). These will be weather measurements
In that event, I would have thought that response times would be the least of your problems and I'm sure you will find the Dallas DS18B20, which is commonly used for weather stations, to be entirely satisfactory. The version I use is encapsulated in a metal container on a cable and is polled at one second intervals, which is surely faster than any weather station needs. There is a little bit of lag to be seen when the test heat source, me, is removed, but I am prepared to put that down to a problem in theory rather than one in practice.
I imagine the bare device on wires, which is more commonly used in weather stations would have a considerably faster response than mine.
The SHT11 has a response time of 5-30s which is quite slow but more than fast enough for a weather station. Your outside temperature won't change that fast and if it does, it's a miss-measurement.
The Dallas DS18B20 sensors are quite accurate, relatively fast (about 0.1s if not in parasite mode) and easy to attach to an Arduino, so I agree with NickPyner about this sensor being a good choice for you.
The Dallas DS18B20 sensors are quite accurate, relatively fast (about 0.1s if not in parasite mode) and easy to attach to an Arduino
The speed of Dallas depends on the resolution 9..12 bit == 8 integral part and 1..4 bits decimal part
There is a good lib - MilesBurton.com - with samples
First of all, I said weather measurements, not that I was planning to create a "normal" weather station. The project does require a fast response temperature measurement since we're measuring temperature changes in "wind layers" so we need the measurement to reflect the altitude we're at as soon as possible.
define fast ?
I'd say that <0.5 sec should be sufficient.
Good to know about the DS18B20, that was one that I'd been looking at in fact. I'll also try the diode implementation probably.
I've found two other sensors that seem to look good as well:
According to the datasheets (if I'm not misreading or misunderstanding them) the first one claims "Faster conversion time (standard mode each) 7.5ms (max)" and the second one claims "Time between start convert command and data available in the Pressure and Temperature registers 1.6 ms (typ) - 3 ms (max).". Anybody have any experience with those two?
The speed of Dallas depends on the resolution 9..12 bit == 8 integral part and 1..4 bits decimal part
Er, I think the speed depends on the (insulating) plastic case the part is in...
If you need fast sensor response time, look for sensors that are not in plastic cases - e.g. a bare thermocouple junction. I haven't dealt with RTDs or thermistors, maybe those can respond quickly as well.
You've got separate time issues here: the time it takes the actual (analog) sensor to reflect a change in environmental temperature, and the "conversion time", which is the time it takes to get that analog sensor value converted to digital.
You also need to look at the speed your sensor (or the air around it) is moving, and see if the speed you think you need makes sense. For example:
You use a sensor/ADC combo that requires 10ms to sample and return a value. Say you put this on a weather balloon with a 1000 ft/min ascent rate. During the 10ms period, the balloon will rise 0.2 inches. Do you really need 2 tenths of an inch resolution?
If you're not flying the sensor, maybe you should describe your setup and what you're trying to measure.
Speed of response to an air temperature is very dependent on forced-air circulation - air is a very efficient thermal insulator if stagnant. Thermocouple probe sounds like a good choice if in a forced draught.
You measured wind-layers - are you floating with the wind or flying against it? (The latter is likely to work nicely anyway).
Even thermocouples of different wire gage size will have different response times. The mass of the sensor element being used is a big contributor to it's response time. So look for the physically smallest micro size sensor type to have the fastest response times.
