Earlier I wrote about my DIY photogates. They work pretty well but there is always room for improvements. So I added a little 16×2 LCD display to the Arduino setup. That way, you can use the large computer-displayed stopwatch or you can rely on the little LCD. Both work simultaneously and on the same Arduino time base;-) The new sketch is here: gates2
Without the USB power from the computer, you will have to find a different power source, but the Arduino will work with very different ones. I tested four or six AA NiMH packs and a 9V wall-wart. An USB wall-wart which could take a normal A-B USB cable (not a fixed mini-B or Micro-B) would also work.
Our maglev track for the Science Olympiad (the reason for all of this;-) is also ready for first tests;-) It’s 3″ wide (the maximum) and six feet long. The rules only require a four feet long track, but that way there is a `braking room’ on both side. All the way at both ends, a pair of reversed magnets will really slow down the vehicle;-)