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Automatic street light prototype
Embedded·Jan 1, 2022
Automatic Street Light
A small controller that turns lights on at dusk and off at dawn using a light-dependent resistor.
Overview
My first taste of real "control" — measure ambient light, cross a threshold, switch a lamp. It is small, but it is one of the most useful little circuits to actually build because you can put it on a balcony or a gate and watch it pay for itself.
Specifications
RoleCircuit designer and prototype builder
SensorsLDR light sensor
ModulesRelay / transistor switchLED or lamp load
ProtocolsAnalog thresholdGPIO
Tech tagsLDRAutomatic LightingRelayEnergy SavingEmbedded
Architecture
Ambient light sensor feeds a threshold circuit/controller. The output switch turns lighting on in darkness and off in daylight.
Project photos
Videos
Implementation details
Firmware
Firmware or analog threshold logic reads the LDR level and switches the output with hysteresis to avoid flicker around the transition point.
Power
Low-voltage control section switches the lamp/load through a driver or relay stage.
Components / BOM
LDR, Comparator or microcontroller, Relay/transistor switch, LED/lamp load
Engineering challenges
Avoiding flicker at dawn and dusk when the light level keeps crossing the threshold.
Solutions
Used hysteresis around the threshold so the lamp does not flutter when the ambient light is borderline.
Results & metrics
Reliable automatic switching from light to dark and back, demonstrated on a small lamp load.
Future improvements
Add solar charging, a motion-based dim mode, a weather-proof enclosure, and remote monitoring for a small street array.