In order to provide an on-demand, open electrical engineering laboratory, we developed an innovative software-based Virtual Open Laboratory Teaching Assistant (VOLTA). This web-based virtual assistant provides laboratory instructions, equipment usage videos, circuit simulation assistance, and hardware implementation diagnostics. VOLTA allows students to perform laboratory experiments anywhere at their convenience. A series of studies was carried out in an experimental section of our traditional entry-level electric circuits laboratory to answer the hypothesis: students taught using VOLTA will learn as much as students who were taught by a human teaching assistant. The experiments were conducted using a pre-test/post-test design, and student performance was assessed using ANOVA on gain scores. Statistical analysis revealed that the student performance increased significantly when VOLTA was integrated into a closed laboratory. We conclude that VOLTA can support students in open and closed laboratories as effectively as a human teaching assistant.