> The problem is that in general, thermistors have a non-linear
> Ohms/degree curve.  To handle that, you can either
> a) accept non-linear response,
> b) use hysteresis instead,
> or c) go through the incredibly complex calculations to determine the
> temperature from the resistance.

I know, that's why I'm asking about the LM35

> As to using the LM35 in a liquid measurement situation, I would go
> for something like this:
>
> 1)Find a short (no more than a cm or two) piece of brass tubing that
> is only slightly larger than the diameter of the curve of a TO-92
> package.
> 2)Get some small silicone tubing that will fit over the brass tubing
> 3) Fill one end of the brass tubing with epoxy to create a seal
> 4)Insert something like heatsink grease , adding just enough that the
> TO-92 package has a good thermal contact to the sides of the tubing.
> 5)Solder wires to the LM35, and heatshrink any bare metal
> 6)Slide the silicone tubing over the wires to the LM35
> 7)Insert the LM35 into the brass tubing witht he heatsink grease
> 8)Push the silicone tubing over the brass tubing, creating a seal,
> but not going over the area occupied by the LM35
> 9)Now, install it anywhere that you want, within a cooling system.
> You have a sealed temperature measurement device.  I wouldn't
> recommend this for anything near food, though.
>
> There's probably a simpler way of doing that, but that's what came
> off the top of my head.

That isn't a really bad idea, but I don't think I can fit that in the tubes
without seriously restricting flow... maybe I could do it with a smaller
SO-8 or TO-46 package... or maybe bolting a TO-220 to a small metal strip
(copper), of cource isolated, and inserting the metal strip into the water,
that is the first thing that popped in my head.
Or maybe there is a much easier, better way and somebody wants to enlighten
me with his knowledge/experience (tubing size varies between 3/8" and 3/4"
OD) :)

Jan

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