Temperature sensor recommendation?

smbaker

Any recommendations for a good temperature sensor to interface with the prop?

My first thought was to use a DS1620 which I used in a few projects many years ago, but I see a thread or two here about accuracy problems. This seems to correlate with my memories of my previous DS1620 projects that always seemed to read hotter than it really was (at the time I blamed it on proximity to voltage regulators or other heat-generating devices). I'm looking for something to measure ordinary ambient room temperature. I see there are a couple of OBEX objects for the DS1620 already, which is some indication other people have been using it. Just looking for opinions on whether or not there's something more accurate out there before I start prototyping up another DS1620-based design.

Thanks,
Scott

T Chap

I never tried the 1620, but I use the MAX6634 on projects and like it, I2C, easy to use.

ElectricAye

I've used the DS18B20 for some time, though I confess I've never rigorously tested it for accuracy.

search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=ds18b20

I think the link below will lead you to the object in OBEX that drives it, though it doesn't state it explicitly in the OBEX description, so read the download. The version linked below will not handle negative temperatures, however, so if you need negatives, let me know and I can post the fix for that.

obex.parallax.com/objects/342/

I also have code for changing the resolution so the sensor will run a little faster but maybe less accurately, if you need it.

Erik Friesen

I took a quick look at the datasheet for the ds1620, and if it is powered with >3.0v, the accuracy is +-0.5C . I don't think you'll find better. I have used the fm75, which has a speced accuracy of +-1.0C.

Don't discount using an ADC and your own sensor, like the lm235z which can be calibrated. The mcp9800 is not bad, but doesn't boast any better specs than the 1620.

On checking accuracy with temp sensors, who is to say what is right? Who sets the gold standard? If you don't have a calibrated instrument, I have my doubts you can rely on any better than +-0.5C in an inexpensive off the shelf unit.

WBA Consulting

If you are looking for accuracy, the SHT11 is rather nice and the object for it is easy to use. I have one of my modules left if you were interested; they are $15.

my site with more details on my module with the SHT11:
www.aestheticacoustics.com/

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Andrew Williams
WBA Consulting
PowerTwig Dual Output Power Supply Module
My Prop projects: Reverse Geo-Cache Box, Custom Metronome, Micro Plunge Logger

bambino

http://www.analog.com/en/sensors/digital-temperature-sensors/tmp04/products/product.html
I like to use this one a lot because the propellers counters make good use of it. It outputs a frequency comparable to temperature that a propeller pin can read easily. You just need one current limiter between it and the prop for the tmp04 or one pull up to 3.3 volts for the open drain tmp03 version.
Comes in a handy TO-92 flavor or smd.

It's accuraccy is good for most projects, but those mentioned earlier in this thread(especially the sht models) are better when you need more precision.