Switching a circuit by resistance

[holographicpencil]

Hello there,

I'm sure this is a bit of dumb question but I haven't yet found any answers.

Basically I have a sensor that changes its resistance proportionately to temperature and would like to make a circuit that goes 'High' when a certain resistance is reached.

I feel like this should be both a common and also simple thing to do but I cannot think how to do it and would appreciate any input

Thanks in advance

[xrunner]

Think "voltage divider". As the resistance increases or decreases across one resistor (the sensor) it will start to drop more or less voltage than the other stable value resistor. You can use that as the input to the next stage.

[Connoiseur]

You can feed the voltage xrunner pointed out, to a comparator or a Schmitt trigger, to get the required high or low state. Use Schmitt trigger if you want a bit of hysteresis in order to prevent any oscillations during transition.