Schematic Circuit Diagram Op-Amp as a Summing Amplifier/Adder proteus simulation

Voltages from various sources referred to the common ground are added in this circuit. The gain of the output can be controlled by selecting appropriate resistance values. If R1=R2=R3=R=2*Rf  then output, Vout=Va+Vb+Vc. By varying the Rf value, gain of the circuit can be controlled.

Op-Amp as Summing Amplifier

This is Non-Inverting summing amplifier. If the common node of resistors is connected to V- terminal then it is called Inverting summing amplifier. The output of inverting amplifier for above mentioned resistor values is, Vout=-(Va+Vb+Vc). The output of Non-Inverting Summing amplifier follows the equation,

Output equation of Summing Amplifier

Simulation of Op-Amp as Summing Amplifier