Hi Oliver (and everybody else),

If you want to make this a real challenge, here are my suggestions.

First, control the flow rate of the dripping water. Ideally design the drip tube (vary the diameter) such that a single pulse from the µ-controller will produce a single drop. This will allow you to choose the number of drops apparent along the vertical drip path at strobe time.

Second, control the phase (relative to the strobe) at which the drips are produced. This will allow you to control the position of each drop along the vertical at strobe time.

Remember that position will not be a linear function of time, so some calculations will be necessary if you want multiple drops to be evenly spaced in the vertical (and you will).

Finally, once you've done these things, you can simply produce an array of such drip columns and you have a scrolling message board, similar to an LED array only much more interesting and cooler.

Joe