As far as I understand an interesting project information via computer is determined irrigation irrigation is done in the required time data exchange via RS232 com port has made the source code and diagrams that can be easily applied, but not a project requires some expertise
Flower Watering Test
Flowers cast? No buck! That done long for me this little device. From time to time, I must just replenish the bucket and from time to adjust the Giessintervalle. The box includes a clock and switches 6 small pumps in programmable time intervals. You can also the moisture in the potting soil measured. But I do not remember after I twice my shack under the water did.
source : chbergmann.de Computer Controlled Flower Watering Circuit with ATmega8 schematic source code alternative link
Laser Sound Transmission Line Transformer
A simple laser communicator. How would you like to talk over a laser beam? In about 15 minutes you can set up your own laser communication system, using cheap laser pen pointers and a few parts from Radio Shack.