Traffic lights

(See Traffic lights on Wikipedia)

Twisted pair

(See Twisted pair on Wikipedia)

Auto racing flags

• 
  Start / Restart
  (Universal)
• 
  Caution
  (Universal)
• 
  Slow down to 60 kph
  (FIA)
• 
  Slippery sections
  (Universal)
• 
  Pits closed
  (IndyCar)
• 
  Stop
  (Universal)
• 
  Safety vehicle on track
  (IndyCar)
• 
  Safety vehicle on track
  (ChampCar)
• 
  Final lap
• 
  Give way
  (Formula 1)
• 
  Give way
  (Other series)
• 
  Mandatory pit
  (Universal)
• 
  Mechanical problem
  (Formula 1)
• 
  Driver misbehaviour
  (Formula 1)
• 
  Disqualification
  (NASCAR)
• 
  Disqualification
  (IndyCar)
• 
  Finish
  (Universal)
• 
  Stage finished
  (NASCAR)