compact fluorescent light, energy-saving light, and compact fluorescent tube. The CFL was initially designed to replace the incandescent lamp in terms of its compactness as well as energy efficiency. The basic construction of a CFL consists a tube which is curved/spiraled to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp compact fluorescent light, energy-saving light, and compact fluorescent tube. • The CFL was initially designed to replace the incandescent lamp in terms of its compactness as well as energy efficiency. • The basic construction of a CFL consists a tube which is curved/spiraled to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp

1. CFL & LED lamps

2. Compact Fluorescent Lamp (CFL)
• compact fluorescent light, energy-saving light, and compact
fluorescent tube.
• The CFL was initially designed to replace the incandescent lamp
in terms of its compactness as well as energy efficiency.
• The basic construction of a CFL consists a tube which is
curved/spiraled to fit into the space of an incandescent bulb,
and a compact electronic ballast in the base of the lamp.

4. How Compact Fluorescent Lamp (CFL)
works – Working Principle
• A CFL uses vacuum pipe which is principle wise same to the strip
lamps (commonly known as Tube light) .
• Tube has two electrodes on both ends which is treated with
Barium.
• Cathode is having a temperature of about 900º C and generates
a beam of electrons which is further accelerated by potential
difference between electrodes.

5. • These accelerated electrons strike Mercury and Argon atoms which in
turn results in the arise of a low temperature plasma
• This process initiates the radiation of Mercury in Ultra violet form.
• Tube’s inside face contains ‘Luminophore’ whose function is to
convert Ultra violet light into visible light.
• This tube is fed with AC power supply which facilitate the changing
functionality of Anode and Cathode.
• The CFL also consists a switched mode converter. It functions on a
very high frequency and acts as a replacement of ballast (choke) and
starter assembly.

6. Circuit Explanation of CFL
• The CFL PCB is quite compact and fits in the holder base.
• Though being compact, it efficiently performs the requirements
as a choke.
• Key components of PCB of CFL
The PCB of a CFL contains the following key components :
• Bridge rectifier made up of diode 1N-4007
• Suppressor for suppressing interference
• Filter capacitor
• Fuse point
• Supply point

8. Phase wise Circuit Explanation of CFL
• The working of a CFL can be divided into two broad phases: –
• Starting Phase
• Normal Phase
• Starting Phase
• The starter segment comprise of a Diac, C2, D1 and R6. The
components D3, R3, D2 and R1 work as a protection circuit and
the rest as normal operation circuit.
• D refers for diode
• R refers for Resistor
• C refers for Capacitor, and
• Q stands for Transistor

9. • The Diac, C2 and R2 send a voltage pulse to Q2 Transistor’s base which
causes it to get its threshold value and it starts operating.
• As soon as the operation starts, the D1 diode blocks the whole section.
• Capacitor C2 is also discharged (after charged to its full value) each time
the transistor Q2 operates.
• Therefore after its first start, There is not enough energy left for reopening
of Diac.
• Further, the transistors are excited with the help of TR1 transformer.
• As the voltage is raised from resonant circuit (L1, TR1, C3 and C6), the
tube lights up as soon as resonant voltage is specified by capacitor C3
(which feeds Filaments).
• At this moment the voltage C3 is over 600V.

10. • Normal Phase
• Just after the ionisation of gas present in the vacuum-pipe, the
practical shorting of capacitor C3 is carried out.
• This results in stepping down of the voltage. After that C6 starts
driving the changer. A very small voltage is generated by this
change, yet it is sufficient to run the lamp in ‘ON’ condition.
• Under regular running condition, if the transistor comes in
OPEN state, The current being fed to TR1 keeps increasing till
the core of transformer saturates, and thus the feed to base
drops down resulting it to close the transistor.
• Immediately after this process, the second transistor is excited
by reverse winding of TR1 and so the process goes on.

11. • Advantages of Compact Fluorescent Lamp (CFL)
• The advantages of CFL are as follows: –
• It is energy efficiency
• It has a higher life span ( nearly five to fifteen times) compared to the old
filament bulbs.
• It has lesser power rating (almost 80 percent) compared to the old filament
bulbs.
• It is low life cycle cost. Though, it has a higher purchase price than an
incandescent lamp, it can save over five times its purchase price in
electricitycosts over the lamp’s lifetime.
• Disadvantages of Compact Fluorescent Lamp (CFL)
• It takes more time to start
• The initial Purchasecost is high.
• It does not comes in dark shades too.
• Like all other fluorescent lamps, CFLs contain mercury, which complicates
their disposal.

12. How is performance affected by ambient
temperature?
• Performance characteristics of compact fluorescent lamps will be
affected by lamp base position and by operation in cold or hot
environments.
• Temperature impacts both short-term and long-term performance. In
the short-term, temperature impacts CFL light output, electric power,
and luminous efficacy,with most lamps operating at their peak in an
ambient temperature of about 77°F (25°C).
• Over long periods of time, elevated temperatures may shorten ballast
life and consequently reduce lamp life in self-ballasted CFLs.

13. Figure 9. Impact of ambient temperature on power, light output, and efficacy of many
fluorescent lamps
Short-term thermal effects
Operating fluorescent lamps in cold or hot environments will lead to
reduced light output, reduced power, and reduced efficacy,as shown in
Figure

14. • Some manufacturers of CFLs report information about light output at a
range of temperatures
• If this information is not available, users can generalize from other curves
showing fluorescent output for minimum bulb wall temperature or
ambient temperature, such as Figure

15. Figure 10. Impact of ambient temperature on
light output of amalgam and nonamalgam
fluorescent lamps
As shown in Figure reduction in light output
can be minimized with the use of a
mercury amalgam
Use of mercury amalgam with CFLs is often not
reported in lamp catalog information.
However, users can request this information
from the lamp manufacturer.

16. LED lamp
• An LED lamp or LED light bulb is an electric light for use in light
fixtures that produces light using one or more light-emitting diodes
(LEDs).
• LED lamps have a lifespan many times longer than equivalent
incandescent lamps, and are significantly more efficient than most
fluorescent lamps, with some LED chips able to emit up to 303
lumens per watt (as claimed by Cree and some other LED
manufacturers).
• However, LED lamps require an electronic LED driver circuit when
operated from mains power lines, and losses from this circuit means
that the efficiency of the lamp is lower than the efficiency of the LED
chips it uses.

17. • The most efficient commercially available LED lamps have efficiencies
of 200 lumens per watt (Lm/W).
• The LED lamp market is projected to grow by more than twelve-fold
over the next decade, from $2 billion in the beginning of 2014 to $25
billion in 2023, a compound annual growth rate (CAGR) of 25%.
• As of 2016, many LEDs use only about 10% of the energy an
incandescent lamp requires.

18. • Similar to incandescentlamps (and unlike most fluorescentlamps), LEDs
come to full brightness immediately with no warm-up delay.
• Frequent switchingon and off does not reduce life expectancy as with
fluorescentlighting
• Lightoutput decreases gradually over the lifetime of the LED (see Efficiency
droop section).
• Some LED lamps are made to be a directly compatibledrop-in replacement
for incandescentor fluorescentlamps.
• LED lamp packaging may show the lightoutput in lumens, the power
consumption in watts,the color temperature in Kelvin or a colour
descriptionsuch as "warmwhite", "cool white"or "daylight",the operating
temperaturerange, and sometimes the equivalentwattageof an
incandescentlamp deliveringthe same output in lumens.

19. • The directional emission characteristics of LEDs affect the design of
lamps.
• While a single power LED may produce as much light output as an
incandescent lamp using several times as much power, in most
general lighting applications multiple LEDs are used.
• This can form a lamp with improved cost, light distribution, heat
dissipation and possibly also color-rendering characteristics.
• LEDs run on direct current (DC), whereas mains current is alternating
current (AC) and usually at much higher voltage than the LED can
accept.

20. • LED lamps can contain a circuit for converting the mains AC into DC at
the correct voltage.
• These circuits contain rectifiers, capacitors, and may have other active
electronic components, which may also permit the lamp to be
dimmed.
• In an LED filament lamp, the driving circuit is simplified because many
LED junctions in series have approximately the same operating
voltage as the AC supply.
• LEDs require a power supply system (driver) to interface them with
the electric network. Generally the current waveform contains some
amount of distortion, depending on the luminaries’ technology.[11]

22. • LED lamps are often made with arrays of surface mount LED
modules (SMD modules) that replace incandescent or compact
fluorescent lamps, mostly replacing incandescent lamps rated from 5
to 200 watts.
• A significant difference from other light sources is that the light is
more directional, i.e., emitted as a narrower beam

23. What is Li-Fi Technology – How it Works, Applications & Advantages
• Li-Fi is a new way of wirelesscommunication which uses LED lights to
transmit data wirelessly.
• The data flow speed of this wireless data communication technology is quite
high and has low cost installation.
It is well accepted that transmission of data is one of the most important day to
day activities in today’s fast changing world. Some problems that is normally
faced are:
• Slow connection to the Internet when multiple devices are connected
• Unavailability of fixed bandwidth due to overcrowding does not allow high
data transfer rates.
• This technology can be a solution to all these problems. Researches are going
on to develop this technology on a broad scope.

24. Fig. 1 – Introduction to Li-Fi
Technology

25. What is Li-Fi Technology
• The term Li-Fi (Light and Fidelity) refers to Visible Light
Communication (VLC) technology. This technology uses a part of the
electromagnetic spectrum that is still not utilized generally i.e. the
Visible Spectrum.
• In simple terms, LiFi is a light-based Wi-Fi. This technology has a
much broader spectrum for transmission compared to conventional
methods of wireless communication which uses radio waves.
• The basic ideology of this technology is transference of data using
LED light of varying intensities.
• It uses transceivers fitted with LED lamps that can transmit and
receive information.
• This results in adding new and unutilized bandwidth of visible light
and may offer additional frequency band than those bands which are
available for RF communication.

26. Fig. 2 – Uses of Electromagnetic
Spectrum

27. • Since LiFi uses the visible spectrum, concerns of adverse effects of
electromagnetic waves (associated with Wi-Fi technology) gets
alleviated.
• Security concerns are also reduced as data or information on the
Internet cannot be accessed in the absence of light.
• How Does a Li-Fi Work
• Li-Fi is a Visible Light Communications (VLC) system and such a
system has two qualifying components:
• One device with a Photo-diode able to receivelight signals.
• A lightsource coupled with a Signal Processing Unit.
• The VLC system signals work by switching bulbs on and off within
nanoseconds such that human eyes are unable to notice it.
• High brightness white LED acts as a light source i.e. as transmission
source.
• A silicon photo-diode with good response to visible light is the
receiving element.

28. Fig. 3 – How Does the Li-Fi Technology
Work

29. • LEDs are switched on and off to generate digital strings of
combination of 1s and 0s.
• To generate a new data stream, data is encoded in the light by
changing the flickering rate of the LED, which is used as the
source.
• The LED output appears constant to the human eye by the fast
flickering rate of the LED.
• VLC data rate is increased by parallel data transmission using an
array of LEDs where each LED transmits a different data stream.

30. • Applications of Li-Fi Technology
• This technology has a wide range of applications such as:
• Public Internet access using existing LED lighting.
• Auto-piloted cars that communicate through their LED based
headlights.
• Connecting with specialists across the globe from the operation
theater.
• Since it uses just the light, it can be used safely in locations or areas
where the presence of radio waves raises concerns of security.

31. • Advantages of Li-Fi technology are:
• Efficiency: Efficient use of energy consumption due to the use of LED
illumination which are already in use for lighting purpose. Hence the
transmission of data will require negligible additional power/ energy.
• High speed: The technology uses bandwidth that is not is use currently.
Hence, low interference, wider bandwidths and high-intensity output are
its key data features.
• Availability: As the light source is available everywhere, availability is not
an issue. Hence, wherever there is a light source, there will be Internet.

32. • Cost Efficient: This technology requires few components for its
working. The technology also uses negligible additional power for
data transmission. Overall, utilization of this technology becomes cost
efficient.
• Security: within a confined area. This internet cannot be intercepted
and misused outsideAs light cannot pass through opaque structures,
LiFi internet is available only to those the area under operation.
• Futuristic: This technology has a great scope in future due to the
extensive growth in the use of LEDs. Overall, it is considered a
sustainable model for Internet access as it incurs lower cost and offers
higher efficiency.

33. • Limitations of Li-Fi
• Some of the major limitations of Li-Fi are:
• Access of internet is limited by the presence of a light source.
• Data transmission speed can get lowered because of interference of
natural light (sunlight) and normal electric light.
• Since light cannot pass through opaque objects, obstacles on
pathways can affect data transmission.
• It has a much shorter range than Wi-Fi.
• Not yet developed for mass scale adoption.

34. Fig. 5 – Strength and Weakness of Li-Fi
Technology

35. •
Li-Fi Wi-Fi
Spectrum Used Visual Light Radio Frequency
Range
Depends on light
intensity,can be lower
than Wi-Fi
Less than 200 meters
Cost
High installation cost,
low regularusage cost
Low cost
Security High Less (compared to Li-Fi)
Data transfer
speed
Higher (compared to
Wi-Fi, can be up to 100
times faster)
High
Availability
Yet to be available for
commercial use
Widelyavailable
What is the difference between Wi-Fi and Li-Fi Technology
Wi-Fi offers highest speed access to internet among the current technology. However, if we compare Li-Fi with Wi-Fi, we find the
following key differences:
Due to the speed and security offered by Li-Fi
technology compared to Wi-Fi, Li-Fi is here to
stay and likely to be used widely.