little wrap-up
The DS18B20 is very likeable solution and it has it all. Those Max people do not miss very much, do they.. Somwhere on another thread I do remember going through pages of sensors and the 1pin solution is very tempting, but originally I have dismissed it because it does require the extra i/face to convert the serial digital information an all the extras to address the chip. I would be quite inclined to look at this solution in the environment of "many" sensors - it is a very elegant option and in line with today's trend to go PIC (they're quite affordable too).
In this project, there is just one temp sensor and I do feel that LM35 would give me the resolution that I want maintaining the ease of interfacing to the rest of (btw - analog) circuitry.
The next obstacle now seems to be the mechanical construction of the sensor itself. The LM35 has an excellent response time when immersed in bath but quite long in the air. As the sampled environment is a "running past" vapour/steam, I need to enchance the propagation of the temperature to the sensor.
Some kind of a "heat-sink" on top of the TO-46 case will improve the propagation but it can not be very bulky because this in turn will introduce inertia. Little bit of a thin copper sheet will do the job, perhaps a "snap-on" heatsink.
The same goes for the pipe the steam goes through. I want to measure the temp of the steam, not the pipe - so the sensor must be thermally isolated from the pipe. This is not a big problem, some teflon here - will do the job.
By the time I am done with this sensor, it will probably "cost" more than a COTS sensor I did like on digikey
but I don't mind to do some experimenting here and this would only be a "mechanical" challenge. It will in turn give me some more insight to the "inertia" issues.
There are many COTS sensors that I would like and could use but their prices are just - to scary. I know, you would say that I only get what I pay for and this is truth, but I do trust - some experimenting here could take me a long way.
Regards,
xanadunow