This simulation shows how an op-amp summing amplifier takes multiple input signals and combines them into one clean output. You can see three different waveforms applied at the input side—typically a sine wave, a square wave, and a triangle wave. Each input passes through an equal-value resistor, which is important because it makes every signal contribute the same amount to the final result. Inside the circuit, the inverting input of the op-amp sits at what’s called a virtual ground. Even though