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Simple Automatic Day Night Switch Circuit

Saving electricity is very important and mostly in city where power is not enough.

This article for Simple Automatic Day Night Switch Circuit show how to make easy auto light switch.

It turn ON or OFF light when outside light changes.

This way people can save money on electric bill.

What is a Automatic Day Night Switch Circuit:

Simple Automatic Day Night Switch Circuit is also called light sensor switch or evening light switch which is made to turn ON light at night or when dark and turn OFF in day or when bright.

Outside lights, streetlight, and other things need auto light control based on outside light.

And this circuit is mostly designed for that.

Circuit Working:

Parts List:

TypeSpecificationQuantity
Resistors10k2
1k1
LDR1
Preset 100k1
SemiconductorsTransistor BC5472
Diode 1N40071
Relay 12V1

This circuit uses two transistors Q1 and Q2 and one LDR.

When light come on LDR its resistance goes up and Q1 turn ON so relay also turn ON.

When there is no light Q1 turn OFF and relay also goes OFF.

This way circuit switches things automatic which is good to control lights in day and night.

Using this simple day night circuit can help save electricity and also helps solve todays energy problem in small way

Formulas:

Below is formula for Simple Auto Day Night Switch Circuit:

LDR (Light Sensor) Resistance:

RLDR ∝ 1 / ILDR

where:

Transistor Q1 Turn ON Voltage:

VT1 = VBE1 + ILDR × RLDR

where:

Transistor Q2 Turn ON Voltage:

VT2 = VBE2 + (VCC − ILDR × RLDR)

where:

Relay Turn ON Time:

τ = RRelay × CRelay

where:

Note:

These formula show how resistance, current and voltage work in this circuit.

With the help of this simple auto day night switch circuit we can make it easily.

How to Build:

Follow the below mentioned steps for building a Simple Automatic Day Night Switch Circuit:

References:

DESIGN AND CONSTRUCTION OF AN LDR 

Design and Analysis of Image as a street light switch

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