Design, implementation and performance evaluation of a low cost AC-DC converter trainer for engineering education

Abstract

This study presents the design, implementation, and performance evaluation of a low-cost, modular AC–DC converter trainer developed to enhance practical instruction in electrical power conversion. In contrast to conventional AC–DC trainer systems, which are often expensive, rigid, and limited in measurement accessibility, the proposed design incorporates a flexible architecture with multiple regulated outputs and accessible test points for real-time observation of circuit behaviour. The system converted a 220–240 V AC mains supply into regulated DC outputs through a step-down transformer, full-wave bridge rectifier, filter capacitor network, and linear voltage regulators (7805, 7812, and LM317). The design process was supported by detailed analytical modeling, including transformer rating selection, rectifier peak voltage estimation, ripple minimization, capacitor sizing, and regulator thermal considerations. The key contributions of this work included the development of a cost-optimized trainer suitable for resource-constrained laboratories, the integration of fixed (5 V and 12 V) and adjustable (1.3–19 V) outputs within a single platform and the provision of enhanced measurement nodes to improve pedagogical effectiveness. Experimental results under no-load and load conditions indicated an unregulated DC output of 15.92 V, ripple voltage below 0.5 V, and stable regulated outputs across all channels. The system achieved an efficiency range of 75% – 78%, which is comparable to or slightly higher than the 70% – 75% typically reported for existing linear AC–DC trainer designs. These results demonstrate that the proposed trainer meets standard performance requirements while offering improved functionality, affordability, and instructional versatility. The system therefore provided a novel and relevant contribution to engineering education, particularly in technical institutions where cost, accessibility, and hands-on learning are critical considerations.