Two-transistor model is used to explain the principle of operation of Silicon Controlled Rectifier (SCR). Since, a SCR is a four layered PNPN device, it can be considered as a combination of two transistors, one transistor as PNP and the other transistor as NPN which are connected back to back. Figure 1: Structure of Two-transistor […]
What is the Two Transistor Analogy (Model) of SCR (Thyristor)? Read More »
A Silicon Controlled Rectifier (SCR) is a four-layer, three-junction semiconductor device used as a switch and rectifier in power control applications. It belongs to the family of thyristors and operates as a controllable switch. SCRs are widely used in industrial electronics, motor control, light dimming, and voltage regulation.
LASER diodes are one of the major optical sources, used in the optical communication for light generating purpose. LASER is an acronym for ‘Light Amplification by Stimulated Emission of Radiation’. It is a device that emits light (electromagnetic radiation) through a process of optical amplification based on the stimulated emission of photons. These are used as
A PN junction diode that acts as a voltage variable capacitor under reverse bias condition is known as varactor diode. The symbol and its equivalent circuit of varactor diode are as shown in figure (1). Figure 1: Varactor Diode.
UJT Relaxation Oscillator is a nonlinear oscillator which generates a non-sinusoidal signal such as sawtooth waveforms as output.
What is UJT Relaxation Oscillator? Working, Circuit Diagram, Waveforms & Derivation Read More »
An N-channel JFET is fabricated (or constructed) on N-type semiconductor bar that is as shown in figure (1). The left end of the N-type semiconductor bar is known as source and the right end is known as drain. Construction of N-channel JFET To design a N-channel JFET, the N-type bar is heavily doped with two
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A current transformer (CT) is nothing but a coil wound on a toroidal core. When a large current carried by a conductor is to be measured, it is advisable to avoid the direct connection of ammeter in this high current circuit. For this purpose a current transformer is used. Fig. 1 : Connection of Current
The three phase autotransformer is a combination of three single phase autotransformers. It has three windings, one per phase. Fig. 1 : 3 Phase Autotransformer.
What is 3 Phase Autotransformer? Working Principle, Connection Diagram & Applications Read More »
Swinburne’s test is the simplest indirect method to determine the efficiency of D.C machine. In this test the no- load losses are measured separately and from their knowledge, efficiency at any desired load can be predetermined in advance. Figure 1: Arrangement of Swinburne’s test.
What is Swinburne’s Test of DC Motor? Theory & Diagram Read More »
Retardation Test is used for finding the efficiency of shunt wound DC machines. In this test, the rotational losses or stray losses are measured and from their knowledge efficiency at any desired load can be determined. Figure 1: Arrangement of Retardation Test.
What is Retardation Test (or Running Down Test) of DC Motor? Theory & Circuit Diagram Read More »