10/5/17Summing Amplifier

Summing Amplifier 

Date : 10/5/2017

Overview

        Summing two voltage inputs into a op-Amp commonly used in circuits to implement mathematical operations.

The output voltage is an inverted and scaled version of the sum of the input voltages Va, and Vb. If R1 = R2, the input voltages are not individually scaled and the output voltage.
Note: R3 = R1, the output voltage is simply the sum of the two input voltages.

given circuit diagram of summing op-Amp

Pre-lab

Design an inverting summing circuit which performs an addition of two voltage inputs. Note, circuit has a virtual ground.

Lab Procedure

For 5 volts for Vcc(+) and Vcc(-)
Set Vb to 1 volt.
Set Va to -4,-2,-1,0,1,2,3, and 5 volts. Record results

Results 

Summing op-Amp741 circuit

Data 

Graph of Voltage (out) versus Voltage (a + b)

Comments

Our results for our summing op-Amp regarding the calculated and actual were identical when using the op-Amp 741. I went ahead and when beyond the voltage input for Va to get values of positive and negative saturation. As seen, when values are within non saturation, and when R3 = R1, the output voltage is simply the sum of the two input voltages. 

Below is verification the circuit using both TinkerCad and EveryCircuit to get a visual representation of the summing op-Amp. 

 Our calculated and actual values for Op-Amp741  matches the calculated value in TinkerCad App.

Summing op-Amp using EveryCircuit App, our calculated, actual and virtual match agree for Vout when Va = 1, Vb= 1, resulting in Vout = -2