OpAmps 1 Purpose Comparator Amplifier An OpAmp can

Op-Amps 1

Purpose Comparator Amplifier • An Op-Amp can be used to either compare two voltages and see which one is greater, or amplify a given voltage 2

Comparator • An Op-amp can act as a comparator to compare 2 voltages • It indicates which is bigger by outputting a voltage (0 V or 5 V) 3

Comparator • The “-” input will act as the baseline • If the “+” input becomes greater than the “-”, +Vss will come out the output 4

Comparator Lab R 1 R 2 5

• Each Op-Amp chip contains Wiring multiple individual Op-Amps 6

Wiring 7

Wiring 8

Wiring 9

Wiring 10

LAB Complete the Op-Amp lab in the book • Lab: Operational Amplifier (Op-Amp) Comparator 11

Amplifier • In the amplifier setup of the circuit, the Op-Amp amplifies the Vin and sends it out of Vout • The setup requires 2 resistors along with the Op-Amp 12

Amplifier – How it works • There are two rules: • Rule # 1: The voltage at “+” WILL equal the voltage at “-” • Rule # 2: No current can enter an Op-Amp 13

Amplifier – How it works • Suppose 0. 0034 V is sensed by Vin • Too little to be sensed by Arduino • By Rule # 1, VA = VB = 0. 0034 A • Voltage drop across R 1 = 0. 0034 V • By V=IR, I 1 = 0. 0000034 Amps V = 3. 4 V B 0. 0034 V • Since no current can enter or exit the Op-Amp, it all must come from R 2 , I 2 = 0. 0000034 Amps • By V=IR, V 2 = 3. 4 V C 0. 0034 V R 2 =1, 000Ω I 2= 0. 0000034 A R 1= 1, 000Ω V 1= 0. 0034 V I 1= 0. 0000034 A D ground 14

Amplifier – How it works A C 0. 0034 V V = 3. 4 V B R 2 =1, 000Ω R 1= 1, 000Ω D ground 15

LAB Complete the Op-Amp lab in the book Lab: Operational Amplifier (Op-Amp) – Amplifier 16