This work describes a Java-based virtual laboratory accessible via the Internet by means of a Web browser. This remote laboratory enables the students to build both direct and alternating current circuits. The program includes a graphical user interface which resembles the connection board, and also the electrical components and tools that are used in a real laboratory to build electrical circuits. Emphasis has been placed on designing access patterns to the virtual tools as if they were real ones. The virtual laboratory developed in this study allows the lecturer to adapt the behaviour and the principal layout of the different practical sessions during a course. This flexibility enables the tool to guide the student during each practical lesson, thus enhancing self-motivation. This study is an application of new technologies for active learning methodologies, in order to increase both the self-learning and comprehension of the students. This virtual laboratory is currently accessible at the following URL: http://personales.upv.es/jogomez/labvir/ (in Spanish).