> 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 -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist