(...) There are some methods involving non-lego peices in the mix. One such method, is to build a touch sensor using a microswitch from a mouse. Wire this in the normally closed way - so when it is activated, it will open. So the motor will go the (...) (20 years ago, 18-Jun-04, to lugnet.robotics)
(...) Instructions for building a diode-based limit switch can be found at (URL) also has a limit switch adapter, that lets you use standard Lego switch sensors to stop a motor without using any sensor ports. (20 years ago, 1-Jul-04, to lugnet.robotics)
