A Water Temperature Detector Circuit

Does anyone have any ideas on making a circuit to detect if some water is too hot/cold. If any of you can supply me with an example circuit please dont make it too complicated.

Thankyou

can you use a simple termistor and a transistor circuit to detect it?
what accoracy do you want?

Hi aws_young,

If you have arrangements to warm things up
if they get too cold, a single switch would be fine.

If you have arrangements to cool things off
if they get too warm, a single switch would be fine.

If you have arrangements that would warm things up,
and also can cool things off, then a single switch
would not be a good idea.

That is because a single switch can only say:
'too hot' or 'too cold' so the system would hunt
between two settings, and could never settle.

It is better to use one for 'too hot'
and another for 'too cold',
that way you can set a gap between the settings,
and the system can settle there for most of the time,
only operating when needed.

Single switch arrangements are fine where temperatures
outside normal ambients are used. Fridges for instance
or ovens, only need single switching.

Best of luck with it,
John