Newbie Question About Switching

Can switches be thrown automatically by the last car passing over that section?
Consider a layout with a large oval, a passing siding on each side, and one
(or even two) nested figure-eights within.
Is it possible to have the last car throw the switch automatically so that on the next pass the train will take the alternate route (and again have the last car throw the switch)?
The intent, of course, would be to have the train run continuously along every foot of track without any intervention.
Alternatively, it seems this could also be used to run two trains on the same layout by automatically causing the trains to take alternate routes.
I have the Wiring Your Toy Train Layout book, but have only skimmed it so far. I have also gotten the RR-Track design software. I need to fire that up and create what I'm thinking of to see if it would work.
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Spender wrote:

Cirkitron(sp) has a turnout alternator that should do what you want except it detects the first unit crossing it.
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That should work fine if the detector is placed before the turnout. That way a train approaching the turnout causes it to select route A, the next train will cause it to switch to route B, the next to route A, etc.
--
Ken Rice -=:=- kennrice (AT) erols (DOT) com
http://users.erols.com/kennrice - Lego Compatible Flex Track,
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Equip your last car with a magnet and use it to close a reed switch when it passes over it, which operates the switch machine through a relay.
(Don't know if this posted alread or not.)
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