→ To study& plot the characteristic of a light emitting diode (LED), LDR, photovoltaic cell, opto-coupler, Photo Diode, Photo Transistor.
The light emitting diode is an opto electronic device .when forward gased, this diode emits light if a particular colour depending upon the band GAP,LED are made of gallium arsenide (Ga AS),gallium arsenide phosphide (Ga AS P)&gallium phosphide (Ga P).this materialare doped to get N-type & p-type material. When excited the electrons jump to higher energy levels there by giving off energy in the of radiation.
The printed circuit board (PCB) consist of an insulating substrate material with metallic circuitry photo chemically formed upon that substrate.thus PCB provide sufficient mechanical support and necessary electrical connections for an electronic circuit. Inter connections between components are achieved by means of conducting paths (metallic conductor pattern) running on or through the substance called tracks. The electrical connection between a land and components terminals achieved by means of solder joint.
Soldering is the process of joining thin metal plates or wires made of steel copper or brass.It is very commonly used to join wires in electrical work and mount electronic components on a circuit board.The joining material used in soldering is called as soldered or filler rod. An alloy of tin and lead iscommonly used as solder.The flux is used to clean the surface of the plates/wires to be soldered.
The CRO ( cathode ray oscilloscope), often referred to as a “scope”, is the most powerful tool available for measuring electrical quantities associated with electronic circuitry. It is such an important instrument that a thorough understanding of its operations is absolutely essential for any electrical engineer. Although we will be using a Digital Storage Oscilloscope (DSO), it is instructive to cover the basics of the Cathode Ray tube technology since there are many still in industry. The display on the CRO screen is created by an electron beam exciting a phosphor coating on the inside face of the CRT (cathode ray tube).Fig.3.1(a) shows the major parts of a Cathode Ray Tube (CRT).