. This will prevent shorts. Then just let the feed in tracks do the powering from each end of the entire setup. However, if your inside track is running left to right (powered) and the outside track is running right to left, you'll get a polarity problem as you run "across" the double crossover...
dont have any pics of it-but lil bro had a complete running subway-under the layout-looked great and was lots of fun `tagging' it
great use for that wasted space (and hides all the wiring too!)
i used photoshop and outlined around the locos shot at the top then copied and pasted over the top of the big boom,then a final cut/paste of small bits of bush and loco on top again to hide the bit where the first photo didnt quite cover up
woodie-that speckled appearance i found was often insufficent light for the ccd to work properly
btw if got a laptop(or even up to dragging the desktop nearby) so that experimening can be instant(different lights etc)
havent tried it for this purpose but..
dick smith and tandy in in .au have 30 sec digital sound recorders built into a keyfob
little bit of resoldering to connect a bigger speaker-relay or pushbutton on panel to trigger sound-bobs ya uncle
(ps these units were about 20 bucks australian 1...