I have 15 'hidden' sidings and not being very able, I need to have track indication LED's on my control panels that are permanently lit green/red depending on whether the different track is occupied or not. Any not too expensive ideas please?
Ons possibility with either dcc or analogue would be to use a latching relay system with either small micro switches or reed switches. One switch is a select to ‘make‘ on the inwards, once that has triggered the latching relay keeps the light on till the select to ‘break‘ makes the relay unlatch to turn the light off. Micro switches are much simpler for this as their 3 pin action gives either a Make or Break depending on how you wire them up. The exit and entry micro switches are as close to the end, beginning of the section you wish to indicate. Of course you would need to duplicate the complete circuit and bits for each siding. I would imagine a similar setup could be done with LGB EPL, but that would be more costly.
Does it *have* to be red/green (one or other is on)? It'll be simpler to have off or on with a single LED, probably where red means blocked/occupied and off means clear.
Are these sidings indoors or outdoors?
For my N gauge layouts I use infra-red detectors by Heathcote Electronics, they work with any stock without modification. Not the cheapest solution, and there are probably cheap sensor modules on ebay which will do a similar job. The great thing with the Heathcote units is they're not affected by ambient light as the sender/receiver work as a pair sending pulses which must bounce back and match. They're indoors only though, although you can get a version with the "eyes" on fly-leads which could be mounted separately from the electronics, the latter being installed in a weatherproof box for outdoors.
Heathcote would have been my first suggestion, but they would certainly not be cheep for 15 sidings. Another relatively inexpensive solution would be a Camera at each end with a split screen option, now they are very inexpensive these days and can work on an old TV that may be kicking around.