Along with modernization, people are more prone to the comfort zone. Several inventions have been made to meet this requirement. Following the same trend, here we have presented a simple circuit; automatic light operated switch using LDR and IC741. People are busy, every second has a vital role in our busy schedule.
Why shall we waste our valuable time turning on every switch in the building? The situation turns more troublesome when one needs to reach the ground floor just because it’s getting dark and s/he needs to turn on the light. The importance of this circuit; the automatic light operated switch is much felt in such traumatic situations.
Who will stay calm being victimized when the solution is right in front of us? To overcome such problems, you don’t need to throw a hefty sum of your hard-earned money. What you need to do is just connect the electric appliances you want to operate automatically with the circuit of an automatic light-operated switch. Then the switch will automatically turn on, LDR will serve its purpose and you will get your surroundings lightened without pressing the switch.
Circuit description of automatic light operated switch using LDR and IC741
The circuit presented here is a light-operated circuit using LDR. LDR is a semiconductor component whose value of resistance is changed according to the intensity of light falling on it i.e. more the light falls on the LDR, the less the resistance is and vice-versa.
The heart of the circuit is a very common operation amplifier IC 741(IC1) and is used herein inverting mode. The LDR is used here as a light sensor and variable resistor; VR1 is used to adjust the sensitivity of LDR. Capacitor C1 behaves as a feedback capacitor. The output from PIN 6 of IC1 (IC 741)is given to the base of transistor T1 through resistor R5, which is used here as a relay driver circuit. Diode D1 is used as a protector and protects the relay from surge current. The load to be controlled is connected to the output pin of the relay.
Hurry up! Reduce your worries and enjoy what the technical world has to offer.
Check out other interesting projects using LDR posted in bestengineeringprojects.com
- Photoelectric switch using ne555
- Self Resetting LDR Alarm using Timer IC 555
- Automatic Light Operated Switch using LDR and IC741
- Automatic Fence Lighting with Alarm
- IC 555 Based Automatic evening lamp
PARTS LIST OF LIGHT OPERATED SWITCH USING LDR AND 741
|
Resistor (all ¼-watt, ± 5% Carbon) |
|
R1 = 1 KΩ R2 = 1KΩ, ½ W R3 = 10 KΩ, ½ W R4 = 10 KΩ R5 = 2.2 KΩ, ½W R6 = 330 Ω, 1/2W VR1 = 470 KΩ |
|
Capacitor |
|
C1 = 0.1 µF, 30V (Electrolytic Capacitor) |
|
Semiconductors |
|
IC1 = 741 (Operational Amplifier) T1 = SL100 or BC148B (Medium Power Silicon Transistor) D1 = 1N4001 (Rectifier Diode) |
|
Miscellaneous |
|
RL1 = 400 Ω, 9V relay SW1 = Double Pole Double Through (DPDT) LDR |
Hi, I would like to make this project. May I know the value of capacitor?
Thank You!
I have Update its value.
sir , Can you tell me ? what is the meaning of RL1 in this circuit?
As is mention is parts list, RL1 is a relay.
plz tell me how can i get output from this circuit? where i will connect LED?
you can get the output from the relay connection, and led is connected after resistor R5 if you want.
thank u sir for reply
please tell us what wiil be the output of this circuit
When the light become low, below it’s threshold level then the appliance (bulb) will turn on. You may also connect a LED at the output after resistor R5 for visual indication to check either circuit is working or not.
what will be the output of this circuit
Q .sir what will be the output of automati light operated switch using LDF and IC 741 Ckt how we will get the output??
When the light become low, below it’s threshold level then the appliance (bulb) will turn on. You may also connect a LED at the output after resistor R5 for visual indication to check either circuit is working or not.
Q sir what will be the output of automatic light operated switch using LDR and IC741 Ckt how we will get the output???
Q sir what will be the output of this Ckt how we will get the output???
how can we connect a relay in this circuit where will we connect normally open and normally closed terminals
Why is sw1 used for?