>Hmm, the problem is there isn't alot of copper tubing...
>most of the tubing is synthetic and doesn't really conduct
>heat that good... maybe insert a small piece of copper
>tube between it and epoxy the LM35 to it... But submerging
>it in the water should be a bit easier... just need a really
>small packaging (so-8? or maybe i should check if maxim has
>a small LM35 like chip...)

There is another possibility, but I think you may find it somewhat more
expensive. IIRC the LM35 is a voltage output sensor. The Analog Devices
AD590 is a current output temperature sensor, but as a sensor I think is
more expensive.

It does have some other nice characteristics however. It is 1uA/K so at 0
degrees C it is 273uA. My favourite method of using it is to have a 10k ohm
resistor to ground at the micro A/D, which then gives 10mV/K which is easily
measured. It's other advantage is that being a current device, it only
require 2 wire connection, and provided you maintain more than about 5V
across the sensor, the wires can be any length. We normally mount a 1nF
capacitor across the sensor leads right at the sensor to stop RF and any
other noise upsetting the sensor. It comes in a metal TO92 package like the
LM35, but also comes in a small flat ceramic package which may be more
easily fitted into a tube for your sort of use.

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