Abstract:

Electrical engineering education is central to addressing challenges such as digitalisation and the energy transition, yet many programmes face declining enrolment and high dropout rates, especially in the first year. Designing laboratory experiences that are both logistically feasible and intellectually engaging for large cohorts, including students working with personal “lab-in-a-box” kits, remains difficult.

We address a specific hardware gap that limits such lab-based learning designs: there is currently no cheap, compact way to provide programmable impedances in the ranges most relevant for introductory experiments. Mechanically tunable capacitors typically cover only picofarad ranges, far below the nF–µF values required in many introductory experiments, and common educational kits rely on fixed discrete components. This makes it cumbersome to realise rich tasks such as parameter sweeps, system identification or black-box investigations.

We present the design of programmable impedance modules tailored to these needs. The concept provides electronically switchable resistances in the typical kΩ range, pure capacitances in the nF–µF range, and several discrete inductance values. They can cover a broad range of introductory circuit labs, operating within the low-voltage levels common in student laboratory equipment (−12 V to +12 V). The modules can also provide composite impedances (combination or resistances and reactances), enabling a broad variety of experimental conditions. They are realised as plug-in boards of the size of a matchbox with a target cost below 10 € and simple digital control for integration into a lab-in-a-box platform. The hardware is being developed within the MEXLEfirst system, but the architecture is generic and transferable to other laboratory platforms.

A central didactic feature is that each module can be presented to students as an unknown component or composite impedance. Students identify the underlying behaviour from measurements - for example by determining resistance from I-V characteristics, capacitance from step responses, or discriminating resistive from reactive behaviour in the frequency domain. This supports inquiry-based, lab-centred learning and system-identification thinking rather than purely procedural circuit assembly. The associated RC and LC filter activities are designed to align with Feisel and Rosa’s classic taxonomy of laboratory objectives, particularly conceptual understanding, design skills, modelling and data analysis.

The paper is positioned explicitly as a design-and-concept contribution. It will provide a clear technical section with block diagrams, schematic overviews, component choices, step sizes and resolution, as well as characterisation of impedance accuracy, switching behaviour, linearity and stability. On the educational side, it will outline a concrete study design for a second-semester laboratory on RC and LC filters, including research questions, hypotheses, instruments, sample and analysis plan, and a focused related-work section situating the contribution among lab-in-a-box, remote-lab and programmable component platforms. At the time of abstract submission, the first prototype generation is being prepared for fabrication; empirical evaluation with students is therefore limited. By the time of the conference, we expect to report on prototype characterisation and to present the planned pilot implementation and evaluation design.

Keywords:

Technology, development, lab-in-a-box, electrical engineering.