>> Why don't you build a small transmitter operating >> at say 200Khz or so and capacitively couple the >> modulated signal to the rails > >That thought occured to me initially but I wondered >about the amount of electrical noise from the motor(s) >going back on to the track That is essentially how Marklin do their new mfx loco decoders. In their case they use a Radio Data System chip at the controller end as the receiver. AFAIK there are patents involved in this, so I suggest you don't try and make it commercially ;) -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist