CHAPTER 3 – Diode Applications

This chapter explores the practical applications of the diode. If the polarity of an applied voltage matches that of the diode, the diode turns “on” and functions as a short circuit. When the applied voltage polarity is opposite (reverse biased), the diode is off. Another good analogy to a diode is the plumber's check valve that allows water in a pipe to flow in one direction but not in the other. The remarkable characteristic of a semiconductor diode is the speed with which it can switch from conducting to nonconducting. One of the most important uses of a diode is in rectification that converts AC to DC. Diodes are also used in waveshaping circuits. A useful modification of a diode is in the form of a silicon-controlled rectifier (SCR). It is popularly used in DC motor speed control and in light dimmers. Industrial SCRs have current ratings in the thousands of amperes and are able to control large amounts of power.