How do you make a dark light sensor?

The dark sensor could be made more controllable by switching the R1 resistor with variable resistor, thus: High resistance-> more darkness to switch on the LED. Low resistance-> less darkness to switch on the LED. A basic voltage divider is formed between the LDR and the resistor R1=100kR.

Which sensor is used to detect darkness?

LDR (Light Dependent Resistor): LDR or Light Dependent Resistor is one of the commonly used light sensors. In this project, we are using an LDR to detect darkness i.e. when the intensity of light decreases.

How can LDR be used as a switch?

LDR switches are used to switch a relay or other device when light are present or absent. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are illuminated with light resistance drops dramatically.

How do you make a dark sensor with LDR?

Components Required:

1. 1 LDR (Light Dependent Resistor or Photo-resistor)
2. 1 npn Transistor (I used BC547)
3. Resistors: 470R, 1K (For Light Sensor), 47K (For Dark Sensor)
4. Potentiometer (Only if you need adjustable sensitivity): 10K (For Light Sensor), 100K (For Dark Sensor)
5. Breadboard.
6. Power Supply: (3-12)V.

What is LDR darkness sensor?

LDR is a photoresistor is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity, in other words, it exhibits photoconductivity. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits.

What is dark light sensor?

Introduction: Dark Sensor ( Light Sensor / Automatic Street Light ) it is a simple and powerful concept , which uses transistor ( BC 547 NPN) as a switch to switch ON and OFF the street light system automatically . It automatically switches ON lights when the sunlight goes below the visible region of our eyes.

Is LDR a transistor?

Simple transistor circuits with LDR are very common and utilised in night lighting and emergency lighting systems. The transistor may directly drive a low-current LED or bulb, or a relay coil, which then acts as a switch to control a high-current load.

How does a LDR sensor work?

Working Principle of LDR. These devices depend on the light, when light falls on the LDR then the resistance decreases, and increases in the dark. When a LDR is kept in the dark place, its resistance is high and, when the LDR is kept in the light its resistance will decrease.

What is the principle of LDR?

The working principle of an LDR is photoconductivity, which is nothing but an optical phenomenon. When the light is absorbed by the material then the conductivity of the material enhances. When the light falls on the LDR, then the electrons in the valence band of the material are eager to the conduction band.

Can a transistor be used for a dark light sensor?

Dark/Light sensor using transistor. Automatic dark detector senses darkness. As the light level decreases and LDR meets the maximum threshold resistance, the circuit automatically switches on the LED D1.

How does a dark sensor relay switch work?

The device uses the LDR light-sensing property to turn the device on. It means when there is no light on the LDR board, the circuit will activate the relay switch. The LDR (Light Dependent Resistor) has very high resistance in darkness as much as 10 Meg ohms which in bright light decreases to a few ohms.

What is the purpose of the dark sensor circuit?

The dark sensor circuit is very useful to Automatic Switch ON and OFF any appliance by Detection of Light and Dark. LDR is a photoresistor that is used for the detection of light.

Can a transistor switch be used as a light switch?

Here is my new simple Electronics project about Automatic Street Light Control System or Dark Sensor. it is a simple and powerful concept , which uses transistor ( BC 547 NPN) as a switch to switch ON and OFF the street light system automatically .