Introduction: USB Powered Traffic Light
This simple project is built on a single sided PC Board. All components are surface mounted except for the 3 LEDs. Of course, a microcontroller version would require many less parts but here you don´t need a programmer and all the components are economical and easy to find. I have it running all time on my office desktop connected to an USB port. Current drain is very low, an average of 25mA.
Step 1: PC Board
PC Board is single sided. Only drill holes for the LEDs. All other components are surface mounted.
Step 2: PC Board, Component Placement & Templates PDF
On this PDF you will find The PCB, placement guide and templates for the VISORS and back cover.
Print on glossy coated paper for the toner transfer. The visors are made directly with the print. For the back cover ant top triangle use light cardboard.
Step 3: LEDs & Lenses
LEDs are STRAW HAT lens type for a wide angle beam. External lenses are "bead surface" 60° lenses for good diffusion of the light.
Step 4: The Circuit Diagram
Step 5: Circuit Operation Details
Step 6: Remove the Thin Ends of IC Pins
This is for easier surface mounting.