Experiment 2 - Input Voltage at the Comparator

In the next step you connect to the comparator the input voltage which you want to compare with the reference voltage.

In the circuit shown, you connect the negative input (pin 3) of the comparator to a potentiometer P1.

Circuit diagram input voltage at comparator.

Input voltage at comparator circuit. (Enlarge)

When you turn P1, you measure, with your multimeter, an input voltage V_in which you can adjust continuously between V_in(min) = 0V and V_in(max) = 9V.

Now you can observe the following...

• Is V_in greater than the reference voltage V_Ref, the LED1 lights up.
• Is V_in smaller than V_Ref, the LED1 remains dark.

Your comparator circuit compares the input voltage V_in to the reference voltage V_Ref and shows you which voltage is greater...