OSSYNTHS soundsystems

    sounds for models of trains and machinery and more 

The sensors in the track are Hall sensors. These sensors are cheap and fit between the narrowest track.

A magnet has to be glued under the locomotive, with the south pole at the underside. The distance between this magnet and the sensor must be 2,7 mm or less. For little locomotives there are two types of magnets available, one has the form of a cube and measures  2x2x2 mm, the other is a cylinder of 2 mm dia by 4 mm long. In the photo the last one can be seen under a HOf diesel 

For bigger scales, in which Shadow can also be used of course, bigger magnets can be placed higher up in the locomotive.