Investigation into the pedagogical value of demonstrating deliberate design deficiencies in PCB design instruction

Sammanfattning: Universities and other higher education institutions have been struggling with high levels of student dropouts and poor graduation rates for a long time. As a result, there has been an interest in modifying traditional teaching techniques and implementing new ones to improve student learning outcomes. Interactive Lecture Demonstrations (ILD) is one such teaching technique which has shown positive results in terms of improving student learning outcomes. An audio recorder and player application with the addition of a DC/DC converter was developed. Six different PCB versions of the audio application were created, containing different combinations of deliberate design deficiencies. The deliberate design deficiencies came in the form of different configurations of decoupling capacitors and ground planes. The DC/DC converter served as a noise source to expose weaknesses in the design. In order to make certain that design deficiencies were exposed effectively, the conversion frequency of the DC/DC converter was switchable between a "high" and a "low" setting. The "low" conversion frequency setting was chosen to comfortably fall in the frequency range of human hearing. Measurements of voltage (time domain and spectral), current spectrum, audio spectrum and radiated emissions were collected. Audio recordings illustrating the impact of decoupling capacitors and interference from the DC/DC converter were performed. The measurement results and audio recordings were used to produce an ILD in video format. The ILD was structured around a modified version of the PODS (Predict-Observe-Discuss-Synthesize) model, which is a four-step process used in ILDs. The ILD contained four separate demonstrations that covered the impact of decoupling capacitors, ground topology and the DC/DC converter on the audio quality and radiated emissions. The ILDs were presented in such a way that the measurement results and audio recordings were correlated with the underlying design theory. Students who had taken either one of two courses related to PCB and electronics design offered at the Royal Institute of Technology (KTH) in the spring of 2019 and 2020 were invited to view the ILD video. The effectiveness of the ILD presentation in terms of pedagogic value was measured via a survey which the students were asked to fill out after watching the video. The results were overall very positive. The feedback received indicate that the students found the demonstrations to be informative and educational. By being able to see and hear the effects of neglecting good PCB design practices in two key areas, the demonstrations were able to provide a more realistic and real-world view of the consequences of neglecting to adhere to good design practices in these two areas that may not be apparent in the theoretical literature. In addition, since PCB design is such a vast subject, the results motivates further developments and study of the ILD concept related to other PCB design concepts such as transmission lines, layer ordering, signal integrity (crosstalk, timing, noise, etc), and others.