PLL Applications 1. Frequency Multiplication or Frequency Synthesis The block diagram of a frequency muliplier (or synthesizer) is shown in figure. In this circuit, a frequency divider is…
How a PLL works ? Consider VCO operating without input signal at free-running frequency fr and input signal of frequency fIN increasing from zero is applied to the…
MONOLITHIC PHASE-LOCKED LOOP (PLL) ICS Although the evolution of the PLL began in the early 1930s but its cost outweighted its advantage in the beginning. Today the PLL…
Operating principle of Phase Locked Loops The block diagram showing operating principle of PLLis given in figure. As illustrated in this fig, the PLL consists of a phase…
Phase Locked Loops (PLL) Introduction to PLL The concept of Phase Locked Loops (PLL) first emerged in the early 1930’s.But the technology was not developed as it now,…
Introduction to Operational Amplifiers In this post, the basics of an operational amplifier (generally abbreviated as op-amp) will be analysed along with its block diagram, basic structure, symbol,…
Programmable UJT (PUT). Programmable unijunction transistor or PUT is a close relative of the thyristor family. Its has a four layered construction just like the thyristors and have…
UJT relaxation oscillator UJT relaxation oscillator is a type of RC ( resistor-capacitor) oscillator where the active element is a UJT (uni-junction transistor). UJT is an excellent switch…
How to trigger an SCR using UJT ? One common application of the uni junction transistor is the triggering of the other devices such as the SCR, triac…
The diacs, because of their symmetrical bidirectional switching characteristics, are widely used as triggering devices in triac phase control circuits employed for lamp dimmer, heat control, universal motor…
Introduction to Diac-Operation and Construction A diac is an important member of the thyristor family and is usually employed for triggering triacs. A diac is a two-electrode bidirectional…
Applications of Triac Next to SCR, the triac is the most widely used member of the thyristor family. In fact, in many of control applications, it has replaced…
Characteristics of Triac Typical V-I characteristics of a triac are shown in figure. The triac has on and off state characteristics similar to SCR but now the char…
Introduction to Triac-Its construction and Operation The triac is another three-terminal ac switch that is triggered into conduction when a low-energy signal is applied to its gate terminal.…
The ability of an SCR to control large currents to a load by means of small gate current makes the device very useful in switching and control applications.…
How to make a full wave rectifier using SCR ? For full-wave rectification two SCRs are connected across the centre taped secondary, as shown in figure-a. The gates…
How SCR functions as a Half Wave Rectifier ? SCRs are very useful in ac circuits where they may serve as rectifiers whose output current can be controlled…
How an SCR functions as a switch ? We have seen that SCR operates either in on-state or in off-state and no other state in between, that is…
90° Phase Control of SCR. In ac circuits, the SCR can be turned on by the gate at any angle a with respect to the applied voltage. This angle…
How to protect an SCR using protection circuits ? SCRs are sensitive to high voltage, over-current, and any form of transients. For satisfactory and reliable operation they are…
How to make series and parallel connections of an SCR ? In many power control applications the required voltage and current ratings exceed the voltage and current that…
Current ratings of an SCR The current carrying capability of an SCR is solely determined by the junction temperature. Except in case of surge currents, in no other…
SCR Voltage Ratings (i) Breakover Voltage. The minimum forward voltage, when the gate is open, at which SCR starts conducting heavily (that is turned-on) is called the breakover…
SCR-Ratings and Specifications The performance of an SCR is affected by the junction temperature, because of change in carrier densities in the four layers and the junction temperature…
Turning-off Methods of an SCR As already mentioned in previous blog post, once the SCR is fired, it remains on even when triggering pulse is removed. This ability…