EasyElectronics

  ·          Light Emitting diode: LED working principle              Construction:              It is a light emitting semiconductor device with a single p-n junction intended to convert electric energy into light energy.              It is fabricated using gallium phosphide (GaP), gallium arsenide (GaAs) and silicon carbide(SiC).              Depending on the material used in LED, the colour of light vary.              Red light- GaAs, GaP      Yellow light-SiC              LEDs are available in round tops as well as square tops with different sizes in millimeters.    ...

  Optocoupler :              An optocoupler is a device that uses a short optical transmission path to transfer a signal   between elements of a circuit, typically transmitter and receiver which are electrically isolated.              It is basically used as isolator circuit. Fig. Circuit Symbol of optocoupler Construction              Basically optocoupler is a pair of LED and phototransistor enclosed in a single package.                           Here LED and phototransistor are isolated so that light may travel across a barrier but electrical current may not. Working Principle Specifications and Parameters :              Device operatin...

  ·          Photodiode : Photodiode  Construction:   Photodiode: construction              The construction of photo junction diode is similar to the p-n junction diode.              But photodiode is placed in a transparent package so that light can reach p-n junction.              The width of the depletion region W is large enough in photodiode, such that most of the photon are absorbed within W rather than n-region or p-region.              W is made large by widely doping any one of the p or n region.              Fig. shows a depletion layer photodiode.   p-i-n photodiode : ...

  ·          Zener diode: Construction:   It is a heavily doped pn junction diode which is always used in reverse bias mode.              The depletion layer is very narrow.              Zener diode can operate in any of the three regions:              i)forward, ii) leakage, iii) breakdown Symbol of Zener Diode: In Zener diode, the barrier separating the two bands is very narrow, hence tunnelling of electrons from p-side valence band to the n-side conduction band occurs. This constitutes a reverse current from n-region to p-region which is called as Zener effect. At a particular voltage, a very sharp reverse current increases sharply and this voltage is known as Zener breakdown voltage. Because of this property, Zener diode is used as voltage regulators...

What is Semiconductor???  - It’s conductivity lies between that of conductors and insulators.  - Conductivity increases with increase in temperature.  - They have negative temperature coefficient(NTC) of resistance.  Free electrons and holes are charge carriers              E.g. Ge, Si, GaAs.             Types of Semiconductors:              1. Intrinsic Semiconductors             2.   Extrinsic Semiconductors                           Intrinsic Semiconductors : Extremely pure semiconductor crystal is called as intrinsic semiconductor.              Extrinsic Semiconductors :       ...