My intention is to use reed switches for the track sensors, as they fit the needs of ‘non contact’ and ‘cheap’ (ish).
This method only requires a magnet to be fitted to the riding trucks, leaving them electronics (and complication) free. Furthermore, should a guest driver wish to use the track, they can either use one of the club riding trucks, or simply attach a magnet to their own in the appropriate place.
On the subject of the club riding trucks, and the ‘appropriate place’ – mounting the magnets on the trucks should be fairly simple, as they are constructed mainly from mild steel (and thus, magnetic!) so magnets can be stuck anywhere flat on the underside of the truck giving great freedom with regards to fine tuning.
The track sensors themselves will be simple reed switches arranged in parallel such that any switch action will cause an input on the microcontroller to be pulled low.
These ‘sensor bars’ are to be mounted on the inside of the outermost rail (The left-most rail in the image here) as this is where the origonal sensors (microswitches) were mounted by means of bolts through said rail, thus we can re-use the mountings as they were left.
I’m going to write another post covering the design of the `sensor bar’s once I have drawn up the schematics.