If you really wanna know, I used one in a level of my own.

To use it, place a Pulse Light in an empty space. The speed must be set to 200.

Then, place a blue spring beside it, leaving two empty tiles inbetween. The blue spring must have a generator.

Then, place a belt event underneath the spring, which belt depends on where the spring is located...
If the spring is located right to the pulse light, place a Belt Right, if it's right to it, a Belt Left.

So:

I simply did that on both sides of the pulse light so it'll work in any case. =b

Disguise: Return of the editing stick, ph33r part 2!