(...) controlled crossings in the near future...just haven't got a chance to get any Mindstorm sets... I think my inspiration came from the old classic 12 Volt level crossing with its own motorized lift gates and lights....you can still get this but (...) (23 years ago, 15-Jun-01, to lugnet.robotics, lugnet.trains)
(...) similar, but used 4 light sensors, 2 in parallel like this: Crossing -> | | ===...=== <- Track X1 X2| |X3 X4 X2 & X3 are in parallel, when X1 is broken, boom goes down & stays down while either X1, X2 or X3 is broken. Similarly for X4. This (...) (23 years ago, 15-Jun-01, to lugnet.robotics, lugnet.trains)
