special purpose diodes

 

Zener diode:

It is a silicon PN junction device.

it upgrades in rewards Breakdown region.

when diode reach reverse breakdown, its voltage remains almost same and current changes drastically.

 reverse Breakdown region is a normal operating reason for dinner diode.

 instead of a straight line at cathode Zener diode has banned line like later Z.

Zener and avalanche breakdown:

1.     Occur in Zener diode at low reverse voltage.

2.    near Jenner breakdown voltage the field is instance enough to pull the electrons from their violence band to create current.

3.    breakdown voltage less than 5 volts.

4.    occurs in Zener diode at high reverse voltage greater than 5 volt.

5.    Zener or commercially available with breakdown voltage from less than one volt to more than 250 volts with specified tolerance from 1%to 20%.

Breakdown characteristic:

1.     A Zener diode operating in breakdown acts as a voltage regulator because itS maintain a nearly constant voltage across its terminal over a specified range of rivers current values.

2.    A minimum value of rivers Crown i z k must be maintained in order to keep the diode in breakdown for voltage regulation.

3.    Maximum current IZM above with the diode may be damage due to excuse a power dissipation.

Application of zener diode:

1.    As a voltage regulator.

2.    provide constant DC level AT output.

3.    products from over voltage.

4.    used in clippings circuits.

5.    prevents output signal from going by on the determined values.

6.    use to shift voltage converting a signal from one voltage to another.

Led semiconductor material:

1.    gallium Areneid was used in early LED and emits IR radiation which is invisible. 

2.    the first invisible red led is we are produced using Helium are slide phosphide on gallium arcinoid substrate.

3.    Letter Gap used as light emitter to achieve pale green light.

4.    by using a red and green cheap LEDs were able to produce yellow light.

5.    the First super bright red yellow and green LEDs reproduce to using Gilliam and arsenide phosphide.

6.    by the early 1990 Ultrabright LED uses in Indium Gilliam able in red orange yellow and green.

7.    blue LED using silicone cardboard and ultrabright blue LEDs made of Gilliam nitride.

8.    high instantly LEDs that produce green and blue are also made using Indium gallium nitride.

Application of led:

 

1.    Indicator lamp.

2.    read out display.

3.    7 segment display.

4.    Infared LED.

5.    TV remote control.

6.    high instantly LED,

7.    traffic lights.

8.    indoor outdoor lights.

9.    high intensity LED.

 

Light emitting diode:

1.    When the device is forward boys then it emits light.

2.    In forward bais electrons cross the PN junction from the end type material and recombine with holes in the P type material when recombination take place the recumbent recombining electrons release energy in the form of photons the emitted lights to be monochromatic one colour some Led EMIT photons that are not part of the visible spectrum but have longer wavelength and are in the infrared Proton of the spectrum.

Photo diode:

o   It is a device that operates in Reverse boys it has small transparent window that allow light to strike the PN junction in Reverse boys there is small rivers leakage current in photodiode when PN junction exposed to light inverse current increase with the instantiary of light when there is no light present then reverse current is a negligible  and is called dark current application is light sensor.