With the advent of Power Functions in trains, I have been working to overcome the potential electrical problems. I have published some circuits to help:

How to control an IR train in a tunnel:
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2957467
Connect as many IR output devices as you need to, to cover the length of the tunnel.

Simple PF lead mods,
how to power a PF IR receiver from a 9V source,
how to overcome the PF 4-channel limit, and how to reduce interference from rogue remote handsets at shows (by cascading PF IR receivers):
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2963520
Cascading will stop anyone with a single handset from moving any motors (though they could still stop ones that are moving). It will also allow up to 128 motors or 256 lights to be controlled.

How to keep train lights on in the right direction when the train stops.
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2953589

From any of those pictures, go up and have a look around the folder. I hope you'll find these circuits useful, especially now that an NXT with a HiTechnic IR Link sensor can act as a PF IR remote handset (and do the PF PWM commands as well).

Mark

Now that I have a the Emerald Express and have played with it some I have found that with the new controller once you have the train rolling it will keep rolling at the same speed even if the controller is out of range. Since this is an IR system all I did was to start the train and then take the controller out of the room and try to change the speed. It did not change. So, unless you want to stop the train in the tunnel you do not need to have any IR transmitters in the tunnel.

The new controller has two controls. In the Emerald Night one controls the motor and the other controls the lights of which there are two. You can turn the lights on or off separately without effecting the speed of the train.

Also, at Brickfest, where we were in a large open space and a large layout, the controller would not go through buildings. In a smaller room like at home the IR will bonce off the white walls and ceiling.

Just thinking that in a tunnel you might be able to use mirrors at the ends that would reflect the IR signal to the train. Maybe a small convex mirror that would reflect the signal all over the tunnel.

Please note that I am not an electrical or IR engineer and do not know if my ideas would work.

Quote by: Mark+Bellis

Simple PF lead mods,
how to power a PF IR receiver from a 9V source,
how to overcome the PF 4-channel limit, and how to reduce interference from rogue remote handsets at shows (by cascading PF IR receivers):
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2963520
Cascading will stop anyone with a single handset from moving any motors (though they could still stop ones that are moving). It will also allow up to 128 motors or 256 lights to be controlled.

Mark

I'm really intrigued about overcoming the four channel limit. This would really help me out, but I don't understand the circuit diagrams at all could you add further explanation of how this is achieved please?

I'm wondering what success, if any, people have had using electric rail and modding some pickups to power PF or RC motors.

There are people looking for dead 9V motors to do this, but I was wondering if someone's come up with a more generic solution.

Forgive me if this is answered in the original post... the brickshelf links don't seem to work for me.