SEMICONDUCTOR(PN-JUNCTION DIODE)

A pn-junction diode (rectifier diode) is formed by sandwiching together  n-type and  p-type silicon. In practice, manufacturers grow an  n-type silicon crystal and then abruptly change it to a  p-type crystal. Then either a glass or plastic coating is placed around the joined crystals. The  n side is the cathode end, and the  p side is the anode end. The trick to making a one-way gate from these combined pieces of silicon is getting the charge carriers in both the  n-type and  p-type silicon to interact in such a way that when a voltage is applied across the device, current will flow in only one direction

SEMICONDUCTOR DIODES

Adiode is a two-lead semiconductor device that acts as a one-way gate to electric current flow.  When a diode’s  anode lead is made more  positive in voltage than its  cathode lead—a condition referred to as  forward biasing—current is permitted to flow through the device. However,  if the polarities are reversed (the anode is made more negative in voltage than the cathode)—a condition referred to as  reversed biasing—the diode acts to block current flow.Diodes are used most commonly in circuits that convert ac voltages and current into dc voltages and currents (e.g., ac/dc power supply). Diodes are also used in voltage-multiplier circuits, voltage-shifting circuits, voltage-limiting circuits, and voltage-regulator circuits.

SEMICONDUCTOR LECTURE 2 DOPING

Doping Doping refers to the process of  “spicing up”  or adding ingredients to a silicon wafer in such a way that it becomes useful to the semiconductor-device designer.

Many ingredients can be added in the doping process, such as antimony, arsenic, aluminum, and gallium. These ingredients provide specialized characteristics such as frequency response to applied voltages, strength, and thermal integrity,

SEMICONDUCTORS 1INTRODUCTION lecture 1

The most important and perhaps most exciting electrical devices used today are built from semiconductive materials. Electronic devices, such as diodes, transistors, thyristors, thermistors, photovoltaic cells, phototransistors, photoresistors, lasers, and integrated circuits, are all made from semiconductive materials, or semiconductors.1 What Is a Semiconductor? Microchips Solar cells Materials are classified by their ability to conduct electricity. Substances that easily pass an electric current, such as silver and copper, are referred to as conductors. Materials that have a difficult time passing an electric current, such as rubber, glass, and Teflon, are called insulators. There is a third category of material whose conductivity lies between those of conductors and insulators. This third category of material is referred to as a semiconductor. Asemiconductor

How to wire up two switch DIY

Two way light switch using 3 core cable
There are different ways to connect up two way lighting
circuits, if it is a new installation the ideal way is to use a
three core & earth cable between the two light switches
Method 2
Two way lighting circuit using three core & earth cable
Line diagram of a two way lighting circuit using junction boxes
(fig 1).
fig 1
The junction box should be wired as shown below.
fig 2
Explanation of above picture . (fig 2)
The feed cable comes from a previous junction box or from
the consumer unit, the red, black and earth wires are
connected to separate terminals. The earth wire must be
covered with green/yellow sleeving.
The cable going to the first light switch is connected as
follows (fig 2). The red wire going to the switch is connected
to the same terminal as the red wire from the feed cable, the
black wire from the switch is connected to the spare terminal
(terminal not yet used), and the earth wire is connected to the
same terminal as the earth wire from the feed cable.
The black wire from the switch, should be marked with red tape
or red sleeving to show it is a live wire, but in practice is often
left unmarked.
The cable going to the ceiling rose is connected as follows
). The red wire going to the ceiling rose is connected to
the same terminal as the black wire ( marked with red tape or
red sleeving ) coming from the light switch, the black wire
going to the ceiling rose is connected to the same terminal as
the black wire from the feed cable and the earth wire going to
the ceiling rose is connected to the sa