fals e
STREET LIGHTS THAT GLOW FOR 1/2KM ONLY
ON DETECTING VEHICLE MOVEMENT
Submitted
By
fals e
ABSTRACT
IR Sensors used on either sides of the road send
logic commands for the LEDs at the output to get
glowing for a patch ahead.
 Intensity control is also possible by pulse width
modulation based on sensing the movement and
density of vehicles.
 Thus this way of dynamically changing intensity
or off to on helps in saving a lot of energy.
 A programmable microcontroller is engaged to
provide different duty cycle for different
intensities at different density conditions.

PREVIOUS TECHNOLOGY

High intensity discharge lamp (HID) presently
used for urban street light are based on principle
of gas discharge, thus the intensity is not
controllable by any voltage reduction method as
the discharge path is broken.
PRESENT
DAY TECHNOLOGY
White Light Emitting Diode (LED) based lamps
are soon replacing the HID lamps in street light.
 As these LEDs can switch faster than HID lamps
we can apply PWM concept to these LEDs.
 LEDs consume less power compared to HID
lamps.
 Life time of LEDs is also more.

BLOCK DIAGRAM
HARDWARE REQUIREMENTS

TRANSFORMER (230 – 12 V AC)

VOLTAGE REGULATOR (LM 7805)

RECTIFIER

FILTER

PIC MICROCONTROLLER (PIC16F877A)

LEDS

PHOTODIODES

POTENTIAL DIVIDER

BC547

1N4007

RESISTORS

CAPACITORS
POWER SUPPLY
230 V AC
50 Hz
12V step down
transformer
Bridge rectifier
Filter(470µf)
5v Regulator
5V DC
DESCRIPTION OF POWER SUPPLY




The circuit uses standard power supply comprising of
a step-down transformer from 230v to 12v and 4
diodes forming a Bridge Rectifier that delivers
pulsating dc which is then filtered by an electrolytic
capacitor of about 470microf to 100microF.
The filtered dc being un regulated IC LM7805 is used
to get 5v constant at its pin no 3 irrespective of input
dc varying from 9v to 14v.
The regulated 5volts dc is further filtered by a small
electrolytic capacitor of 10 micro f for any noise so
generated by the circuit.
One LED is connected of this 5v point in series with a
resistor of 330ohms to the ground i.e. negative voltage
to indicate 5v power supply availability.
fals e
PIC MICROCONTROLLER(PIC16F877A)
High-Performance RISC CPU:
• Only 35 single-word instructions.
• All single-cycle instructions except for program branches, which are two
cycle.
• Operating speed: DC – 20 MHz clock input DC – 200 ns instruction
cycle
• Up to 8K x 14 words of Flash Program Memory, Up to 368 x 8 bytes of
Data Memory (RAM), Up to 256 x 8 bytes of EEPROM Data Memory.
• Pin out compatible to other 28-pin or 40/44-pin, PIC16CXXX and
PIC16FXXX microcontrollers.
Special Microcontroller Features:
100,000 erase/write cycle Enhanced Flash program memory typical.
• 1,000,000 erase/write cycle Data EEPROM memory typical.
• Data EEPROM Retention > 40 years.
• Self-reprogrammable under software control.
• In-Circuit Serial Programming™ (ICSP™) via two pins.
• Single-supply 5V In-Circuit Serial Programming.
•Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable
operation.
• Programmable code protection.
• Power saving Sleep mode.
• Selectable oscillator options.
• In-Circuit Debug (ICD) via two pins.
•
Peripheral Features:
Timer0: 8-bit timer/counter with 8-bit prescaler.
• Timer1: 16-bit timer/counter with prescaler, can be incremented
during Sleep via external crystal/clock.
• Timer2: 8-bit timer/counter with 8-bit period register, prescaler and
postscaler.
• Two Capture, Compare, PWM modules
- Capture is 16-bit, max. resolution is 12.5 ns
- Compare is 16-bit, max. resolution is 200 ns
- PWM max resolution is 10-bit
• Synchronous Serial Port (SSP) with SPI™ (Master mode) and
I2C™ (Master/Slave).
• Universal Synchronous Asynchronous Receiver Transmitter
(USART/SCI) with 9-bit address detection.
• Parallel Slave Port (PSP) – 8 bits wide with external RD, WR and
CS controls (40/44-pin only).
• Brown-out detection circuitry for Brown-out Reset (BOR).
•
PIN DIAGRAM OF PIC16F877
PWM(PULSE WIDTH MODULATION)

The term duty cycle describes the proportion of on time to the regular
interval or period of time; a low duty cycle corresponds to low power,
because the power is off for most of the time.

Duty cycle is expressed in percent, 100% being fully on.

The main advantage of PWM is that power loss in the switching devices is
very low. When a switch is off there is practically no current, and when it is
on, there is almost no voltage drop across the switch.

PWM works also well with digital controls, which, because of their on/off
nature, can easily set the needed duty cycle.

The longer the switch is on compared to the off periods, the higher the
power supplied to the load is.
PHOTO DIODE
A photodiode is a type of photo detector
capable of converting light into either
current or voltage, depending upon the
mode of operation.
Photodiodes are similar to regular
semiconductor diodes except that they
may be either exposed (to detect vacuum
UV or X-rays) or packaged with a window
or optical fibre connection to allow light to
reach the sensitive part of the device.
IR LED




An IR LED, also known as IR transmitter, is a
special purpose LED that transmits infrared
rays in the range of 760 nm wavelength.
Such LEDs are usually made of gallium
arsenide or aluminum gallium arsenide. They,
along with IR receivers, are commonly used as
sensors.
The appearance is same as a common LED.
Since the human eye cannot see the infrared
radiations, it is not possible for a person to
identify whether the IR LED is working or not,
unlike a common LED.
To overcome this problem, the camera on a cell
phone can be used. The camera can show us
the IR rays being emanated from the IR LED
in a circuit.
PWM(PULSE WIDTH MODULATION)
OPERATION OF PROJECT

There are two basic modes of operation,
1. Transition of streetlights from dark to bright state.
2. Transition of streetlights from dim to bright state.

In the first mode of operation, when the vehicle is not
present, all the streetlights will be in dark state. When
a vehicle is sensed then the window of streetlights is
illuminated in front of the vehicle.
SECOND MODE OF OPERATION

In the second mode of operation, initially when the vehicle is not
sensed, all the streetlights will be in dim state. This is achieved by
use of pulse width modulation technique through the program stored
in the microcontroller.

When a vehicle is not present on the highway, then the streetlights
are made to glow for about 1ms and then for 100ms they are
switched off. Thus, we get streetlights with less brightness.

When a vehicle is sensed, all the streetlights are illuminated for 1ms
and the window of streetlights are illuminated for 100ms. Thus we
have a PWM wave of 99% duty cycle.
APPLICATIONS
Highways
 Industries
 Museums

ADVANTAGES
Power saving
 LEDs consume less power
 Easily implementable
 Low cost
