Arduino - Traffic lights for your restroom Configuration Waiting delay before change state (seconds) changeStateDelay = 3; Delay after is long presence (seconds) longPresenceDelay = 120; Yellow light - Short duration (seconds) shortOutDuration = 20; Yellow light - Long duration (seconds) longOutDuration = 180; Bill of materials 1 x Arduino Nano 1 x Sensor HC-SR04 3 x LED G4, 12/24v DC 3 x Relay KY-019 5V DC / 220V AC-DC 1 x Potentiometer 10k Ohms 1 X Power 12v DC Wiring