A diode is a two-terminal electronic component that allows current to flow in only one direction. It is used to convert alternating current to direct current through a process called rectification. Diodes come in various types including laser diodes, light emitting diodes, Zener diodes, and silicon diodes. Rectification uses diodes to convert AC to DC through either half-wave or full-wave rectification circuits. Zener diodes are used in the reverse bias mode as voltage regulators. Photodiodes generate current or voltage when illuminated by light and are used in applications like machine vision, range finding, and medical diagnostics.

2. A Diode is two terminal
electrical device allowing
current to move through it in
one direction.
This unidirectional behavior is
called rectification, and is used
to convert alternating current to
direct current.

3. Representation of diode…

4. 1. Laser diode
2. Light emitting diode
3. Zener diode
4. Germanium diode
5. PIN diode
6. Silicon diode
7. Photo diode etc….

5. Diode in rectifier….
Rectification:-
Simply defined, Rectification is the
conversion of ALTERNATING CURRENT(AC)to
DIRECT CURRENT (DC).

6. Half wave rectifier:-
This involves a device that only allows one-way flow of
electrons. This simplest kind of rectifier circuit is half-wave
rectifier.
It only allows one half of an AC wave form to pass
through the load.
Full wave rectifier:-
A Full Wave Rectifier is a circuit, which converts an ac
voltage into a pulsating dc voltage using both half cycles
of the applied ac voltage. It uses two diodes of which one
conducts during one half cycle while the other conducts
during the other half cycle of the applied ac voltage

7. Half wave rectifier Full wave rectifier

8. Zener diode….
Zener Diodes are used in the "REVERSE" bias mode, i.e.
the anode connects to the negative supply, and from its
I-V characteristics curve
 It is used in regulator, stabiliser, etc

9. Clippers are networks that employ diodes to
“clip” away a portion of an input signal
without distorting the remaining part of the
applied waveform.

10. A clamper is a network constructed of a diode, a resistor, &
a capacitor that shifts a waveform to a different DC level
without changing the appearance of applied signal.
Clamping network have a capacitor connected directly
from input to output with a resistive element in parallel
with the output signal. The diode is also in parallel with the
output signal but may not have a series DC supply as an
added element.

11. LEDs emit light when an electric current passes
through them.
LEDs can be damaged by heat when soldering.
LED never connected directly through battery or
power supply because instantly too much current will
pass through and burn it out.

12. USES…
Household appliances, VCR/ DVD/ Stereo/Audio/Video
devices, Toys/Games Instrumentation, Security
Equipment, Switches.
Mobile Phone, PDA's, Digital
Cameras, Lap Tops, General
Backlighting.
Etc…..

13. Photodiodes are semiconductor light sensors that
generate a current or voltage when the P-N junction in
the semiconductor is illuminated by light.
Features of photodiode
1.Excellent linearity with
respect to incident light
2.Low noise
3.Wide spectral response
4.Mechanically rugged

14. Uses….
1. Dental science
2. Blood analysis
3. Cancer detection
4. DNA analysis
5. Machine vision
6. Range finding
7. X-ray film marking
etc….