Development of a Laboratory System for the Study of Discrete-Circuit Basic LC Oscillators

This work presents the structure and the principle of operation of a laboratory system intended for laboratory practice in the course of Analog circuitry. The developed laboratory system has functional capabilities for experimental testing of two oscillator circuits generating sine waves, namely the LC oscillator with transformer-based positive feedback (Meissner oscillator) and the Colpitts oscillator. The study of the circuits initially started with testing of the selective LC amplifier for the Meissner circuit and a study of the LC frequency-selective network for the Colpitts configuration. The positive-feedback loop consisting of an amplifier and а frequency-selective network is then investigated at different operating points of the used transistors and various passive components in the positive feedback. In this way, the student's knowledge acquired on the basis of the lectures, as well as the acquisition of new practical skills, are strengthened. The developed laboratory system is intended for use by second-year students in the Bachelor's degree programs in "Electronic Information Systems" and "Automotive Electronics" at the Technical University of Sofia. Also, the system can be used for laboratory work in the course "Electronic Modules and Systems – Analog and Digital" studied by third-year students in the Bachelor's degree program of "Aeronautical Engineering"