Principle 19. Periodic action

1. Instead of continuous action, use periodic or pulsating actions.
   Hitting something repeatedly with a hammer
   Replace a continuous siren with a pulsed sound.
2. If an action is already periodic, change the periodic magnitude or frequency.
   Use Frequency Modulation to convey information, instead of Morse code.
   Replace a continuous siren with sound that changes amplitude and frequency.
3. Use pauses between impulses to perform a different action.
   In cardio-pulmonary respiration (CPR) breathe after every 5 chest compressions.