Laboratory Workstations in Electrical Engineering

Abstract

Computers, configured for data acquisition and control, have been used in undergraduate laboratories at Cornell University's School of Electrical Engineering since the early 1970s. The introduction of personal computers in the introductory laboratory course sequence (Fall/Spring of Junior Year) has permitted a dramatic expansion of this practice. Previously, computers were used in group experiments with limited student interaction. Now each student has access to an IBM Personal Computer with analog and digital input/output capabilities as well as the usual electronic instruments. Instructionally, data acquisition is emphasized during the fall semester. BASIC commands and programs are implemented to exercise analog-to-digital and digital-to-analog converters. A "canned" program collects samples (to 20,000 samples/sec) and performs spectral analysis (FFT) on periodic waveforms including the exciting current of a transformer. Three experiments in the spring semester demonstrate the capabilities of the laboratory workstation. (1) The spectral analysis program is used to demonstrate aliasing and examine distortion in a class-B amplifier. (2) A computer controlled experiment determines the impurity profiles of p-n junctions by sampling the capacitance as a function of reverse bias. (3) Filter circuits are tested automatically for transient and frequency response using the computer. Numerical integration, FFT, and inverse FFT are used to simulate circuit responses.Cornell Universit