LDR Sensor

Ldr sensor
a light dependent resistor (ldr), also known as a photoresistor, is a type of resistor whose resistance varies according to the amount of light that falls on it. the resistance of an ldr decreases as the intensity of light increases, and it increases when the light intensity decreases. ldrs are commonly used in light-sensing applications such as light meters, street lighting systems, and automatic lighting control systems.

ldr sensors are often integrated with circuits for projects that involve detecting light levels, like light-sensitive switches, light-based alarms, and environmental monitoring. the working principle of an ldr is based on the photoelectric effect, where photons from light free up electrons, causing the material's resistance to drop.

specifications of ldr sensor
general characteristics
-type: photoresistor
-material: typically made from cadmium sulfide (cds) or similar light-sensitive materials
-light sensitivity: high sensitivity to visible light
-application: light intensity sensing, light detection
electrical characteristics
-resistance (dark): can range from 10 mω to 20 mω (depending on the ldr model)
-resistance (light): typically between 1 kω to 20 kω (depending on light intensity)
-maximum voltage: 150v
-maximum power rating: 100 mw
optical characteristics
-light spectrum: detects light in the visible spectrum (380 nm to 750 nm)
-peak sensitivity: generally peaks at around 500 nm (green light)
-response time: fast response to light changes (typically in milliseconds)
-linear response: some ldrs have a nearly linear response to light intensity changes, while others may have a logarithmic response.
environmental conditions
-operating temperature: -40°c to 80°c (varies by model)
-humidity: can operate in a wide range of humidity levels (80% rh max)
physical characteristics
-package type: typically available in cylindrical or flat packages
-size: varies by manufacturer (usually small, often in the range of 5–20 mm in diameter)
-wavelength range: 380 nm to 750 nm
applications
-automatic lighting systems: turning lights on/off based on ambient light levels
-light meters: measuring light intensity
-solar energy systems: monitoring sunlight for solar panel efficiency
-security systems: detecting presence or changes in lighting conditions
-clocks & watches: automatically adjusting brightness based on light exposure