Automatic streetlights use a photocell and transistor circuit to detect low light levels and switch streetlights on at dusk and off at dawn. When light levels are high, the photocell allows current to flow through the transistor, keeping the lights off. When it gets dark, there is no current and the lights turn on automatically. This helps conserve energy by only powering the lights when needed. The system can save over 40% of the electrical energy used for street lighting. While initial costs may be high, the long-term energy savings and minimal maintenance requirements make automatic streetlights an effective way to save money while helping the environment.

1. Automatic
streetlight
By Dhyani Panchal

3. What is automatic streetlight?
• It is a simple and powerful concept, which uses transistor as a switch to
switch ON and OFF the streetlight system automatically. It automatically
switches ON lights when the sunlight goes below the visible region of our
eyes.
• Transistor is a semiconductor device for amplifying, controlling, and
generating electrical signals.
• Semiconductor is any of a class of solids (such as germanium or silicon)
whose electrical conductivity is between that of a conductor and that of an
insulator in being nearly as great as that of a metal at high temperatures
and nearly absent at low temperatures

4. How does this technology works?
• when light shines on the photocell, it turns the transistor on, which
energizes the relay's electromagnet, which turns the light off. When it is
dark, the photocell has high resistance, so no current flows through the
base and the relay is not activated -- the light is on.
• In a real streetlight the circuit might be a bit more advanced, but not a
lot. It has the CdS cell, the transistor and the relay, but might need more
than one transistor depending on the size of the relay.
• The patented cellular distribution system (CDS) is a wireless
enhancement product designed to resolve low cellular signal strength
issues for in-building applications. Designed as a complete kit, the CDS
system provides everything that you will need to mitigate dead zones
within your communications network.

5. EXTRA FACTS!
• Garret morgan invented street lights
• Street lights are commonly made of corrosion resistant metal such as
aluminum or a strong plastic material such as high density polyethylene
to be able to withstand the outdoor elements.
• 240 million people do not have electricity in India.

6. Is this technology necessary?
• This project of AUTOMATIC STREET LIGHTS is a cost effective, practical,
ecofriendly and the safest way to save energy. It clearly tackles the two
problems that world is facing today, saving of energy and also disposal of
incandescent lamps, very efficiently. According to statistical data we can save
more that 40 % of electrical energy that is now consumed by the highways.
Initial cost and maintenance can be the draw backs of this project. With the
advances in technology and good resource planning the cost of the project can
be cut down and with the use of good equipment the maintenance can also be
reduced in terms of periodic checks. The LEDs have long life, emit cool light,
donor have any toxic material and can be used for fast switching. For these
reasons, our project presents far more advantages which can overshadow the
present limitations. Keeping in view the long-term benefits and the initial
cost would never be a problem as the investment return time is very less. The
project has scope in various other applications like for providing lighting in
industries, campuses and parking lots of huge shopping malls. This can also
be used for surveillance in corporate campuses and industries.