Posted by Circuits Arena on Sunday, 9 November 2014
Categories:
555IC,
LDR,
PROJECTS
555 IC AUTOMATIC STREET LIGHT is the artlcle explaining AUTOMATIC STREET LIGHT Description It automatically switches ON and OFF When darkness rises to a certain level then sensor circuit...
AUTOMATIC STREET LIGHT
Description
It automatically switches ON and OFF When darkness rises to a certain level then sensor circuit gets
activated and switches ON and when there is other source of light.When there is a need of light by using this circuit.When darkness rises to a certain level then sensor circuit gets activated and switches ON daytime, the street light gets OFF. But for high power switching one can connect Relay (electromagnetic
switch) at the output of pin 3 of I.C 555 that will make easy to turn
ON/OFF.
Project Model
Circuit Operation
I.C 555 circuit uses a popular timer is connected as comparator with pin-6 connected with positive rail, the output goes high(1) when the trigger pin 2 So small change in the voltage of pin-2 is enough to change the level of output (pin-3) from 1 to 0 and 0 to 1. High and low are out puts and can not remain in any intermediate stage. It is powered by a 6V battery for portable use. The circuit is economic
in power consumption. Pin 4, 6 and 8 is connected to the positive supply
and pin 1 is grounded. To detect the present of an object we have used
LDR and a source of light.
whose value depends on the brightness of the light which is falling on LDR and LDR is a special type of resistance . LDR has resistance of about 1 mega ohm when in total darkness It responds to a large part of light spectrum.
Potential divider circuit with LDR and 100K variable
resistance connected in series. Voltage is directly
proportional to conductance so more voltage we will get from this
divider when LDR is getting light and low voltage in darkness. This
divided voltage is given to pin 2 of IC 555. Variable resistance is so
adjusted that it crosses potential of 1/3rd in brightness and fall below
1/3rd in darkness. As soon as LDR gets dark the voltage of pin 2 drops 1/3rd of the supply
voltage and pin 3 gets high and LED or buzzer which is connected to the
output and activated.
Components Are
1. L.D.R.
2. 9v Battery with strip.
3. L.E.D (Light Emitting Diode) 3 to 6 pieces.
4. Variable Resistance of 47 KΩ.
5. P.C.B (Printed Circuit Board of 555 I.C).
6. Switch.
Precautions
1. I.C should not be heated too much while soldering this causes may damage the I.C.
2. Check the LDR sensitivity before use on the board by multimeter.
3. Opposite polarity of battery can destroy I.C so please check the polarity before switching ON the circuit.
4. L.E.D glows in forward bias only so incorrect polarity of L.E.D will not glow.
5. Each and every component should be soldered neat and clean.
6. LDR should be so adjusted that it should not get light from streetlight itself.
