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As it is well known, electricity and magnetism are main subjects in order to obtain science degrees at every University around the world. In our extensive experience teaching these subjects we have dealt with the usual difficulties for students learning the different contents. In this sense, laboratory experiments, in which students carry out several targeted experiments, are a powerful tool to overcome these difficulties and to improve the understanding of physics concepts. Nowadays, in research laboratories in Physics and Chemistry the use of complex measurement systems automatized by means of control programs is very common. In these systems, a computer program can control the instrument signal generation and data acquisition, read the results and process them. We have tried to train the students to this procedure, introducing the use of computers in laboratory work from the first courses of technical degrees. However, control instrumentation software is complex to be learnt, so that it is not pedagogically appropriate their use in these courses. In addition, in some experiments, it would be advisable to acquire the raw data by means of a computer in order to be analysed with common software, like popular worksheets, rather than scientific graphic programs.

For this purpose, we have developed a non virtual laboratory session to teach the use of AC signal generators and meters with a two way communication from and to computer, with special emphasis in the communication channel from the computer, that is employed to generate arbitrary waveforms. To achieve it, we have employed an external USB sound card, whose outputs have been cased with the help of a 3D printer, in order to be practically managed in lab table. The output signal can be measured with desk instruments (i.e. multimeter, oscilloscope). In addition, the data obtained with digital oscilloscopes are captured by the computer in a worksheet.

This approach has unambiguous advantages compared with conventional lab sessions, in which students use general purpose test and measurement instruments and take the data by hand. Data capture simplifies this repetitive task and increase the number of experimental data that can be taken, also preventing acquisition errors. Furthermore, computer aided signal generation allows the use of a greater variety of signals than those traditionally available from basic lab equipment. This approach can also be employed to obtain full virtual signal generation and acquisition systems with minor changes.