An alternating current voltage controller or regulator converts a fixed AC voltage source to a variable AC voltage source. The output frequency is always equal to the input frequency. The simplest way to control the AC voltage to a load is by using an AC switch. This switch can be bidirectional switch like a triac or a pair of SCRs connected in antiparallel
Since the easily available voltage is a sinusoid, which alternates as a function of time, the first task is to convert it into a useful and reliable constant (dc) voltage for the successful operation of electronic circuits and direct current machines. The conversion process is called the rectification. Although there are other semiconductors devices suitable for rectification, diodes are frequently employed. A rectifier is a circuit that converts an ac signal into a dc signal or sometime is called ac to dc converter
Power electronic deal with how to control and convert power (electric energy) into one form to another and how utilization of power at high efficiency
The field-effect transistor (FET) is a three-terminal device used for a variety of applications that match, to a large extent, those of the BJT transistor. Although there are important differences between the two types of devices, there are also many similarities that will be pointed out in the sections to follow. The primary difference between the two types of transistors is the fact that the BJT transistor is a current-controlled device as depicted in Fig.1a, while the JFET transistor is a voltage-controlled device as shown in Fig.1b.
One of our first concerns in the sinusoidal ac analysis of transistor networks is the magnitude of the input signal. It will determine whether small-signal or large-signal techniques should be applied. There are two models commonly used in the small-signal ac analysis of transistor networks: the re model and the hybrid equivalent model.
The transistor is a three-layer semiconductor device consisting of either two n- and one p-type layers of material or two p- and one n-type layers of material. The former is called an npn transistor, while the latter is called a pnp transistor. In Fig. below both biasing potentials have been applied to a pnp transistor, with the resulting majority- and minority-carrier flow indicated.
The label semiconductor itself provides a hint as to its characteristics. The prefix semi-is normally applied to a range of levels midway between two limits. The term conductor is applied to any material that will support a generous flow of charge when a voltage source of limited magnitude is applied across its terminals. An insulator is a material that offers a very low level of conductivity under pressure from an applied voltage source. A semiconductor, therefore, is a material that has a conductivity level some-where between the extremes of an insulator and a conductor
The combinational logic circuit is built from logical gates only. While the sequential logic circuit is mainly built from flip flops in addition to logical gates
The logic gates (AND, OR, NAND, NOR, INVERT) used in combinational logic. we will deal with data storage circuitry that will latch on to (remember) a digital state (1 or 0).
SPLD: Simple Programmable Logic Devices: A programmable, digital logic IC containing several PAL or PLA structures with internal interconnections and memory registers.