Experimental track switch. To operate signals we need to detect trains passing certain sections of track. Kev B tried using, at the end of last season, some ultra-sonic sensors to detect trains. This works fine, but needs a lot of setting up and is expensive. So Kev B has reverted back to using micro switches housed in a 3D printed box. The housing is in two parts, first part stays screwed to the sleeper. The second part, containing the switch, can be removed to allow us to test different...