Re: [Phys-l] Cheap Classroom project to sense water temperature

[chuck britton <cvbritton@mac.com>]

At 10:46 AM -0700 5/5/10, John Denker wrote:
> On 05/05/2010 08:06 AM, CARABAJAL PEREZ, MARCIAL ROBERTO wrote:
>
> >  We are working in a classroom project to develope a water temperature
> >  meter. It should be built up with little electronics and using a coil
> >  of wire copper as temperature sensor device. I would like to know if
> >  you have seen something like this working and can bring me any
> >  detail.
>
> I've seen lots of things like that.
>
> Please ask a more specific question.
>  -- What is the point of the project?
>     If all you wanted was a "water temperature meter", you would
>     be better off using a thermistor ... or a liquid-in-glass
>     thermometer.
>  -- How much is "little electronics"? 
>     Does it allow or disallow a digital voltmeter?
>  -- Have you tried it?
>     What (if anything) was non-trivial or non-obvious about it?

A 1000 ohm coil of fine copper wire from a Radio Shack 'reed relay' 
makes a very simple sensor that works between room temp and that of 
liquid nitrogen - but using it for changes near room Temp will need 
'some' (i.e. non-trivial) electronics.