Now that you know the upper and lower "trigger limits" for turning the fan on and off, you need to start calculating values.Reaylly great explanation!! But what about the resistors how can i dermine there values now.
R5. R7. and R6 forms a voltage divider. You should be able to get the desired output from the wiper by doing the calculation. Why do you think R5 and R6 are in that circuit?