Deriving Closed Formula Design Restrictions in Electronics Labs

The Electronics circuit design course is a required course for undergraduate Electrical Engineering students. The objective of electronics courses is to explain the idea of operation of widely used circuits. If the theoretical concept is well understood, students can add modifications to the circuits and implement them as needed in design projects or later in their jobs. Usually, the main design expressions are derived in class. In the lab, they are required to select values for circuit parameters to meet given design specifications. Random selection of circuit elements based on the main derived formula, usually leads to failure of the designed circuit. To obtain a deeper understanding, students are required to investigate the relation of different design parameters from different aspects, visualize the dependency of circuit performance on varying different parameters, and comparing design simulations with built circuits. The Electronics Design course covers oscillator circuits based on Schmitt trigger comparators with the hysteresis effect and multivibrators such as the 555 Timer circuits. The lab introduces students to applications, such as timers and frequency dividers. As part of the assignment, they need to come up with closed formulas for the design restrictions. The objective of this step is to assess how well they understand the circuit's concept of operation. It challenges their creative thinking and develops their insightful analysis skills. The goal is also to help them formulate the design limitations and rules in a reusable format. The obtained design is tested in PSpice simulation, and the formula is presented using MATLAB animation to see the effect of changing different design parameters on the output signal. As a final step, the circuit is built and tested. Thorough investigation of the theoretical design limitations helps in getting better hardware implementation designs. Being able to precisely explain circuit designs and define design restrictions and specifications is an important proficiency for practicing engineers. This paper shares lab designs and results that can be used in Electronics labs to strengthen the fundamentals of circuit design and analysis.