Build A Smart LED Flashlight Using Arduino

How it works:

The flashlight turns on automatic for 60 seconds when it senses that the room is dark enough.

To turn on manual light for additional 60 seconds you need to push the RST button.

The Light sensing LED Flashlight is invaluable for emergencies such as power failures or blackouts.

Step 1: ​The Flashlight Is Invaluable for Emergencies Such As Power Failures or Blackouts.

I have assembly several Flashlight, and have several dozen spear PCB board and components that I can share with any one who wish to make the flashlight.

The instructable contains:

  • Flashlight schematic,
  • PCB Assembly drawing,
  • BOM – Components KIT cost less than $5
  • Tools list
  • Detailed step-by- step assembling instructions.


  • Number of flashlight components: 15
  • Color of LED’s light: white
  • Number of LEDs: 3
  • Light Distance: 2-3 meters
  • Size of flashlight : 26.25mm x 20mm x 5mm
  • Current consumption :
  • LEDs turn ON: 4-5mA
  • LEDs turn OFF: 30-45uA
  • Battery capacity: 140mAh
  • Battery voltage: 3V
  • Battery life : up to 6 months (if flashlight turns on 2 times for 60 sec in 24 hours)
  • Required skills : knowledge of soldering SMD components

Step 2: Light Sensing LED Flashlight Schematics

The Light sensing LED Flashlight Schematics contains the next blocks:

  • 3 White LEDs (LED1 – LED3) and 3 current limit resistors (R1 – R3)
  • 16 bit ultra low power micro-controller of firm Texas Instruments (U1)
  • Power on (R4 and C1) and manual Reset (S1 push-button) micro-controller circuit
  • Light sensor (PH1) and resistor R5 – is voltage divider circuit
  • Flashlight battery 3V, 140mAh

Step 3: The Light Sensing LED Flashlight PCB

I ordered the PCB from a Chinese low cost prototype PCB manufacturer.

The PCB Specification are:

  • Dimensions: 20mm x 26,25mm
  • Layers number :2 Layers
  • PCB Type: Normal FR-4 Board
  • FR4-TG: TG 130-140
  • Thickness: 1.6mm
  • Solder Mask: White
  • Silkscreen: Black
  • Surface Finish: HASL with lead
  • Finished Copper: 1 oz Cu

Read more: Build A Smart LED Flashlight Using Arduino


About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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