"Remote" light-sensor for chronometer

Hi All,

I have created a create a "gate chrono" that can measure all kind of tests, like 5-0-5, accelerations, 10m dash and so forth.

It is based on a laser beam hitting on light-sensor; when the beam gets interrupted, it trigger the chrono (start, stop, lap, or whatever is needed).

Now I am working on a 100m test, where I get a gate every 20m (so 20,40,60,80,100) in order to get the split times.

The original idea was to get a single cable to the sensor to read the analogvalue, whereas the sensor itself was powered by two AA batteries (3V). I founded out this is no possible, as the light-sensor as to be powered from the same source where the analog signal is directed (i.e. the Arduino itself).

Now, is it possible to work around the problem? I am already working on a wireless solutions: bluetooth is working just fine and now I am testing 315Mz modules. Still, I would like to make it work with cables as well.

The ideal plan is to get only one cable down to each sensors, rather than having 3 cables for each gate (sensor, power, gnd).

Any creative ideas? :D

Thank you, and I hope the post is "clear"; if not, please let me know.