INTRODUCTION of automatic street light electronics project
automatic street light electronics project Needs no manual operation for switching ON and OFF. When there is a need of light it automatically switches ON.
When darkness rises to a certain level then the sensor circuit gets activated and switches ON and when there is another source of light i.e. daytime, the street light gets OFF.
The sensitiveness of the street light can also be adjusted. In our project, we have used four L.E.D as a symbol of a street lamp, 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 any electrical appliances that are connected through the relay.
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circuit diagram of automatic street light electronics project
Components Used in this Circuit:
- CA3140 – 1
- R1 (100k) – 1
- R2 (560E) – 1
- R3 (1K) – 1
- R4, R5 (100K) – 2
- VR1 (100K) – 1
- C1 (10uF) – 1
- LDR – 1
- T1 (BC548) – 1
Principle of automatic street light electronics project:
This circuit uses a popular timer I.C 555. I.C 555 is connected as a comparator with pin-6 connected with positive rail, the output goes high(1) when the trigger pin 2 is at lower than the 1/3rd level of the supply voltage.
Conversely, the output goes low (0) when it is above 1/3rd level. 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. The output has only two states high and low 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 presence of an object we have used LDR and a source of light.
LDR is a special type of resistance whose value depends on the brightness of the light which is falling on it. It has the resistance of about 1 mega ohm when in total darkness, but a resistance of only about 5k ohms when brightness illuminated. It responds to a large part of the light spectrum.
We have made a potential divider circuit with LDR and 100K variable resistance connected in series. We know that 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 the potential of 1/3rd in brightness and fall below 1/3rd in darkness.
Sensitiveness can be adjusted by this variable resistance. 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 gets activated.
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