Hands On Project: Have students setup a simple LAN using a star topology

Assignment NO: - 1 DATE:-

AIM: - Design of Linear power supply : 1. Single Polarity 2. Dual Polarity

OBJECTIVE: - To design Linear Power Supply

REQUIREMENTS: - Sr. No.DescriptionSpecificationQuantity

1.Computer(Multisim Software)P-V01

THEORY:-

AC Power:

Typical line voltages in the US are between 110 V to 120 V with a frequency of 60 Hz. However, digital devices require DC power and thus the power supplies can be created.

From Physics 260, the ratio of the input voltage on a transformer to its output voltage follows the relation of

Equation 1where Np is the number of turns on the coil on the primary side (input) and Ns is the number of turns on the secondary (output) side of the transformer.

In Multisim, under the Basic family, a virtual transform can be found. Among its properties is the primary to secondary turns ratio. Examining Equation 1 closely, a primary to secondary turns ratio of 100, will actually reduce the input voltage by a factor of 100. This is called a step down transformer. If the primary to secondary ratio is less than 1 (but greater than zero), then the transformer is a step up transformer.Activity 1:1. Place connect a 60 Hz 120 V AC source on the Multisim screen. Connect this component to the virtual transformer described above (shown to the right). The AC source can be connected either to the two wires on the left of the transformer. The transformer will then follow the relationships described above.

2. Connect the multimeter between the topmost and bottom most wires on the right side of the transformer. Connect a ground to the - of the multimeter. Set the multimeter for AC voltage measurement. Simulate the circuit.

Diodes:Diodes effectively conduct current in one direction. In the early days of electronics, diodes were tubes with two elements: a heating element and a cathode. The heater was called the anode and when current ran through the heating element, it would emit electrons. These electrons were attracted to the cathode (the + side) and thus current would flow. Reversing the current would be impossible because the cathode was made of a different material.

Today semiconductor materials are used to construct these devices. Some materials can be doped or lightly contaminated with other elements. When this occurs, an electron can be easily removed from the doped materials. These are called n-type materials. P-type materials have been doped with elements in which there are holes (absence of electrons). The n-type material is combined with the p-type material. Imagine that you have two types of chocolate bars and you smash then ends together to form a long chocolate bar. One end, for instance, may be a Milky WayTM bar and other a HeathTM. How the bar tastes, then, depends on which side of the bar you eat.

It is a similar in a p-n junction. If you attach a battery with the + to the n-type side and the - to the p-type side, no current flows. Why? The nearly free electron in the n-type material immediately flows there and the electrons from the - battery flow into the holes. There is no current flow across the junction.

Circuit 1Half wave rectifierHowever, if the + side is connected to the p-type side and the - side is connected to the n-type side, current will flow across the diode.

We will use a Wheatstone bridge arrangement of diodes to change or rectify the voltages from the transformer.

Circuit 1full wave rectifierFig. Components of Linear power Supply

Fig. Single Polarity Linear Power Supply

Fig.Output Simmulation

Fig.Dual Polarity Linear Power Supply

Fig. Output Of Dual Linear Power Supply

Fig. Single Polarity Variable Power Supply

Fig.O/p Potentiometer Increment 25%,50% and & 75% respectively

Signature of Staff

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