Build this simple circuit on a plastic breadboard to learn the basics of the comparator. R1 and R2 function as voltage dividers that supply a range of voltages to both 741 inputs. Q1 switches current to the led when the output of the 741 goes high. The circuit works like this: ASSUME R2 IS SET TO ITS CENTER POSITION TO GIVE Vref = 4.5 VOLTS (9V/2 = 4.5V). R1 THEN CONTROLS Vin.
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