>You haven't got much space in the breath-tube - I doubt if you could get this working.
>
>  
>
Well it is done in the medical world ;-)
Some dimensions: 5 cm long, 3cm outside diameter, 1 cm inside diameter.

>>-          Hot wire? .. Nahhh.
>>    
>>
>
>That would work, but you've got the problem that the temperature of the breath isn't predictable 
>
It's quiet predictable and constant within 0.1 Celcius.
And measuring it with a very-very small thermocouple isn't too difficult.

>and is 
>difficult to measure, so probably not a good one. 
>
>  
>

Stef
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