Security Alarm With LDR

About: Share diy projects to those who have the same hobby with me

Hii friend,

Today I am going to make a circuit of Security alarm with LDR.

Let's get started,

Step 1: Take All Components As Shown Below

Components required -

(1.) Battery - 9V x1

(2.) Battery clipper x1

(3.) LDR x1

(4.) LED - 3V x1

(5.) Resistor - 330 ohm x1

(6.) Resistor - 22 ohm/220 ohm x1

(7.) Transistor - BC547 x1

Step 2: Solder LED to the Transistor

Solder -ve wire of LED to collector of the transistor as shown in the picture.

Step 3: Solder 22 Ohm Resistor

Next solder 22 ohm resistor to LDR as solder in the picture.

Step 4: Connect LDR to LED

Now solder LDR to LED as shown in the picture.

Step 5: Now Connect 330 Ohm Resistor

Now solder 330 ohm resistor to emmiter of the transistor as shown in picture.

Step 6: Connect Base of Transistor to 330 Ohm Resistor

Connect base of transistor and other wire of LDR to 330 ohm resistor as shown in the picture.

Step 7: Connect Battery Clipper Wire to the Circuit

Now solder battery clipper wire to the circuit as shown in the picture.

Solder -ve wire of battery clipper to emmiter of transistor

and +ve wire of battery clipper to +ve of LED.

Step 8: Now Circuit Is Ready

Now security alarm circuit is ready.

Step 9: How to Use It

Connect battery then use -

when we give light to LDR then LED is start glowing as picture.

Step 10: After Glowing LED

After glowing LED it can also glow in the dark (night).

it will glow contineous till we will not turn off buy putting any object between LDR and LED in dark.

Step 11: LED Will Be Turn Off

LED will be turn off in dark when we will put any object between LDR and LED.

As in picture I am going to put an object between them.

Step 12: Object Between LDR and LED

Now as you can see in picture when I put an object (paper) between LDR and LED then LED gone turn off.

Step 13: Now LED Is Not Glowing Due to Absense of Light

Picture shows - LED is not glowing due to absense of light in LDR.

Step 14: Again When I Supplied Light to LDR Then LED Is Start Glowing

Again when I supplied light to LDR then LED is start glowing.

This is the whole process that which this alarm circuit is working vice and versa...

Thank you

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