Circuit Simulation of the Analog Computer and Proportional Controlled DC Motor Based on Op Amp

Operational amplifier(op-amp) is a building block of many analog circuits, nowadays it has been the most widely used device in various electronics instruments. In modern electronics design, op-amp has a special weightage due to its robust characteristics. In this paper, two applications of op amp are discussed. One is using op-amp to construct an analog computer for solving second order differential equation. Another is to build a proportional controlled DC motor which transfer input voltage into angle. By varying the proportional gain at 1, 5 and 15, different result is obtained by octave simulation using step response graph and pole-zero diagram.