Summing Amp Lab

For this lab we had to design an inverting summing circuit.

Our two input resistors, R1 and R2 had resistances of 21.2 Kohm and 21.6 Kohm respectively. Theoretically they should R1=22k and R2=22k. Our output resistor had an theoretical resistance of 10k and an actual resistance of 9.7 k.

For this lab we had to keep V1 at 1 V, change the Vb voltage and then measure the output voltage. For the second trial, we had to keep V2 at 1 v, change Va and measure the output voltage again.

For our prelab, we calculated that our out resistor voltage should be

Vo=-(Va+Vb)(R3/R1)



Here's the circuit diagram

Heres a picture of our circuit

Here's our values for constant Va at 1 V

Va=1
vb	vo
-4	1.38
-2	0.46
-1	0
0	-0.42
1	-0.88
2	-1.35
3	-1.81
5	-2.73

 Here's our graph

We noticed that the op-amp reached saturation at 1.38V and -2.73 V

Here's our values for constant Vb at 1 V

Vb=1
va	vo
-5	1.35
-4	1.35
-2	0.44
-1	0
0	-0.43
1	-0.88
2	-1.34
3	-1.79
4	-2.7
5	-2.7

Here's our graph

We noticed that our saturation values were at 1.35 V and -2.7 V