Automatic street light using ldr and also with the help of bridge rectifier

1. Automatic Street Light control
using LDR

2. Group Members
Compiled by :
16BEC0066 - NIKHIL SHARMA
16BEC0653 - VIPIN S RAKARADDI
Submitted to –
Mrs . Sangeetha A

3. Contents
 Introduction
 Circuit Diagram
 Hardware Requirement
 Description of Hardware
 Working
 Bread-board Mounting
 PCB Mounting
 Conclusion

4. Introduction
Many of the people have a phobia of darkness, so to assist
them in such situation, we have explained a simple
circuit. It will automatically turn on street light in the way
of LEDs or bulb coupled with relay. Working this circuit is
very much easy and also the power consumed by the
circuit is very low because of the very few components
used in the circuit.

5. Circuit diagram

6. Components:
 Diodes - 4
 Resistor R1 (10 K) – 1
 Resistor R2 (3300 E) – 1
 Resistor R3 (1 K) – 1
 Variable Resistor VR1 (10 K) – 1
 Capacitor C1 (470uF) – 1
 Capacitor C2 (200uF) - 1
 LDR – 1
 Transistor T1 (BC548) – 1
 Relay-1
 LED-5

7. Description of Hardware :
(1) LDR:
 Sensitivity depends on intensity
of light.
 Resistance of LDR decrease with
increase in intensity of light and
vice-versa.

8. (2) Resistor:
 It is a passive component having two terminals that are
used to manage the current flow in the circuit.
 A current that flows via a resistor is directly proportional
to the voltage that appeared into resistor.
 Two types:
(1) Fixed value resistor
(2) Variable resistor

9. (5) BC548 Transistor :
 It is a general purpose silicon, NPN, bipolar
junction transistor. It is used for amplification &
switching purpose.
 Here, for switching purpose it is
biased so that it remains on if
there is signal at its base , other-
wise it is completely off.

10. Bridge rectifier
 A diode bridge is an arrangement of four (or more) diodes in
a bridge circuit configuration that provides the same
polarity of output for either polarity of input.
 When used in its most common application, for conversion
of an alternating current (AC) input into a direct current (DC)
output, it is known as a bridge rectifier. A bridge rectifier
provides full wave rectification from a two-wire AC input,
resulting in lower cost and weight as compared to a rectifier
with a 3-wire input from a transformer with a center
tapped secondary winding.
 The essential feature of a diode bridge is that the polarity of
the output is the same regardless of the polarity at the input.

11. Capacitors
 A capacitor is a passive two terminal electrical
component that stores electrical energy in an electric
field. The effect of a capacitor is known as capacitance.
While capacitance exists between any two electrical
conductors of a circuit in sufficiently close proximity, a
capacitor is specifically designed to provide and enhance
this effect for a variety of practical applications by
consideration of size, shape, and positioning of closely
spaced conductors, and the
intervening dielectric material.

12. Working of Automatic Street Light
Controller Switch Circuit:
 The working of circuit is very much easy to understand. In
this circuit, we used transformer which will basically
convert the high voltage at input into small voltage. After
it we put bridge rectifier which will convert ac into dc
current and provide pure dc current.
 In this LDR and VR1 form one potential divider . Here
transistor is also placed which will basically act as switch.
Transistor will be operating in cutoff and saturation mode
to act as switch.

15. Bread-board mounting :

16. PCB mounting

17. Advantages:
 No man power required.
 Simple Construction.
 Efficient method.
 Less Consumption of electrical energy.
 Less maintenance.
 Cheap and economical.

18. Conclusion:
 In coming days, this will prove a great boon to the world,
since it will save a lot of electricity of power plants that
gets wasted in illuminating the street lights. As the
conventional sources are depleting very fast, then it`s
time to think of alternatives.