Light Decting Circuit

7,976

18

3

Introduction: Light Decting Circuit

About: None of your buisness

this circuit will make a alarm when the light falls on the ldr

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Things Needed

you need-
1] resistors 100k ohm , 56k ohm , 10k ohm
2] transistors 1 pnp and 1 npn 
3] capacitor 0.04 uf
4] ldr
5] 8 ohm speaker
6] 2 cells
7] battery holder
8] pref board

Step 2: Ldr

A photoresistor, light dependent resistor (LDR) or cadmium sulfide (CdS) cell is a resistor whose resistance decreases with increasing incident light intensity. It can also be referred to as a photoconductor.
A photoresistor is made of a high resistance semiconductor. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity, thereby lowering resistance.

Step 3: Circuit Digram

solder according to the digram.

Step 4: All Done

you can put the circuit in a box when you open the box in a well lit room the alarm goes off!!

Participated in the
Wicked Lasers Contest

Be the First to Share

    Recommendations

    • Trash to Treasure Contest

      Trash to Treasure Contest
    • Raspberry Pi Contest 2020

      Raspberry Pi Contest 2020
    • Wearables Contest

      Wearables Contest

    3 Discussions

    0
    MROHM
    MROHM

    8 years ago on Step 3

    Please!! We need the values of Components Added to your Diagram..Many Thanks!!

    0
    zazenergy
    zazenergy

    8 years ago on Introduction

    I'd love to see this in it's finished form -- perhaps a video is in order. Thanks for sharing!

    0
    robot1398
    robot1398

    Reply 8 years ago on Introduction

    the box was just an idea and i am not able to attach the the video as it says it is more than 10 mb