Different Types of Ammeters and Voltmeters: The following are the different types of ammeters and voltmeters in measuring instruments are PMMC Moving Iron Electrodynamometer Hot wire Thermocouple Induction type Electrostatic Rectifier Of these, the PMMC type can be used for dc measurements only, and the induction type for ac measurements … (Read More)

Working Principle of D Arsonval Galvanometer: The action of the most commonly dc meter is based on the fundamental princi­ple of the motor. The motor action is produced by the flow of a small current through a moving coil, which is … (Read More)

Permanent Magnet Moving Coil Instrument (PMMC): In this type of Permanent Magnet Moving Coil Instrument (PMMC), we have a coil suspended in the magnetic field of a permanent magnet in the shape of a horse-shoe. The coil is suspended so that … (Read More)

Practical PMMC Movement: The basic Practical PMMC Movement (also called a D’Arsonval movement) offers the largest magnet in a given space, in the form of a horse-shoe, and is used when a large flux is required in the air gap. The … (Read More)

Taut Band Instrument: The Taut Band Instrument utilizes the same principle as the D’Arsonval movable coil and fixed magnet. The primary difference between the two is the method of mounting the movable coil. The taut band movement has the advantage of eliminating … (Read More)

Electrodynamometer Instrument: The D’Arsonval movement responds to the average or dc value of the current flowing through the coil. If ac current is sought to be measured, the current would flow through the coil with positive and negative … (Read More)

Moving Iron Instrument | Types of Moving Iron Instruments: Moving Iron Instrument can be classified into attraction and repulsion types. Repulsion type instruments are the most commonly used. Iron vane ammeters and voltmeters depend for their operations on the repul­sion that … (Read More)

Concentric Vane Repulsion Type Moving Iron Instrument: A variation of the radial vane instrument is the concentric vane Repulsion Type Moving Iron Instrument. The instrument has two concentric vanes. One vane is rigidly attached to the coil frame while the other … (Read More)

Digital Display System: The rapid growth of electronic handling of numerical data has bought with it a great demand for simple systems to display the data in a readily understandable form. Display devices provide a visual display … (Read More)

What is the use of Light Emitting Diode (LED)?: The Light Emitting Diodes, Fig. 2.10 (a) is basically a semiconductor PN junction diode capable of emitting electromagnetic radiation under forward conductions. … (Read More)

What is Liquid Crystal Display (LCD)?: Liquid Crystal Display (LCD) are passive displays characterized by very low power consumption and good contrast ratio. They have the following characteristics in common. They are light scattering. They can operate in a reflective or transmissive configuration. They … (Read More)

Gas Discharge Plasma Display | Nixie Tubes – Symbolic Representation: These are the most well-known type of alphanumeric Plasma Display. Their operation is based on the emission of light in a cold cathode gas filled tube … (Read More)

7 Segment Display using Gaseous Discharge: Segmented gas discharge display work on the principle of gas discharge glow, similar to the case of Nixie tubes. They are mostly available in 7 segment display or 14 segment form, to display numeric and … (Read More)

7 Segment Led Display Working Principle: In 7 Segment Led Display, it is usual to employ a single LED for each segment. For conventional 7 Segment Led Display (including the decimal point, i.e. the 8th segment), the wiring pattern is simplified by … (Read More)

5×7 Dot Matrix Led Display Character Patterns: Excellent alphanumeric characters can be displayed by using dot matrix LEDs with an LED at each dot location. Commonly used Dot Matrix Displays of prominent characters are 5 x 7, 5 x 8, and … (Read More)

Incandescent Display using 16 Segment: Incandescent Display has been a basic process of light generation for several decades. This process is now down in fully integrated electronic displays. Incandescent display using 16 segment as well as 5 x 7 dot matrix formats … (Read More)

Structure of Electrophoretic Image Display (EPID): Electrophoretic Image Display is the movement of charged pigment particles suspended in a liquid under the influence of an electric field. This phenomenon has been utilised in electrophoretic image displays, as shown in … (Read More)

Structure of Liquid Vapour Display (LVD): Liquid Vapour Display (LVD) are the latest in economical display technology. They employ a new reflective passive display principle and depend on the presence of ambient lights for their operation. Figure 2.25 gives the structure … (Read More)

Classification of Printers: Character printers and graphic plotters are the two devices used to prepare a permanent (or hard copy) record of computer output. The basic difference between printers and plotters is that the former are de­vices whose … (Read More)