The pulse is like a heartbeat that makes the Bits after it turn on and off in a steady rhythm.The pulse is a switch that opens and closes over and over again. When it's open, it sends an on or 5 volt signal through to the next Bit. When the switch closes, it sends an off or 0 volt signal through to the next Bit.Use the small slider on the board to change the speed of the rhythm. Sliding it right will speed things up, left will slow things down.