There are only six types of tea! That is, only those processed from Camellia sinensis leaves can be called this way. All others, nicknamed herbal teas are in reality tisanes (infusions). Anyway, this exercise will lead you to part of the design of a temperature sensor that monitors temperature of tea brewing (and infusions as well) on the appropriate scale, as indicated in the next table.

Let us make use of a thermistor NTC with at and . Furthermore, assume margin for the temperature range of interest, i.e. 10 % below 70 °C and above 100 °C. Consider the following circuit.

Now, firstly consider the midrange temperature, let us call it and derive based on the inflection-point method, i.e. .

Then, design the remaining circuit obtaining the value of that implies an output at half the power supply when the temperature is at midrange, i.e. . Admit and a linear output voltage range limited to from the power rails, i.e. , which should coincide with the temperature range specified.