Simple blinkers.
Simple blinker or flasher. No fancy ic's (integrated circuits) are required. Perfect for robots. Transistor: (NPN) 2n3904 For an alternate light blinker (like at a railroad crossing) you might try: Blink lights on the parallel port. #!/bin/bash echo "infinite loops [ hit CTRL+C to stop]" for (( ; ; )) do sudo parcon 1h2h3h4h5h6h7h8h pause 1 sudo parcon 1l2l3l4l5l6l7l8l pause 1 done