[SOLVED] The photophone challenge Hi everybody, (reply: "Hi, Dr. Nick" even though my name is not Nick) I saw this design contest near where I live where participants had to design and build an apparatus that would transfer an audible vocal message over a distance of @ least 20m, by using visbile light. Of course, I'm talking about a photophone. Now, my group (me and 3 others) attached a magnet to a diaphragm that would vibrate in accordance with the sound, and since the moving magnet was in a solenoid, it would generate a current. This current would power an array of LEDs. As for the recieving end, we used the traditional selenium solution. Why so convoluted? For one thing, we weren't allowed to use transistors. Only the basic electrical components. I would really like to hear how other people would have approached this. After all, this is not very original, and originality was stressed for the contest (which would explain why we didn't win the grand prize). How would you have done it?