Electronic variation of illumination

Abstract

In this project three circuits were built to produce an automatic repetitive variation of illumination. These were constructed for the purpose of light display for applications in advertisement and also as an attraction in shop windows. Moreover the design of these circuits is based on the theory of power control. Hence three important components used frequently in power control had to be described before proceeding with the actual explanation of the circuits. This project begins by outlining the essential operating characteristics and importance of the triac the unijunction transistor (since two of the circuits built use these two important components). In Chapter II the phase triggering technique used for power control, is explained. The second two chapters deal with the construction of two circuits, which give a cyclic variation of illumination. These two circuits operate on the principle of phase triggering technique. Although the circuits are designed for the purpose of light display and for applications in advertisement, by making some alterations in the circuitry one circuit can be used for speed limitation of electric motors. Chapter 4 explains the importance of the power transistor used in power control, while Chapter 5 deals with another circuit constructed also for similar reasons. However, the power in this circuit is controlled by the use of a power transistor.