New answers tagged trains
One option is to only use the 9V train motor, but power it most of the time with the PF battery back. This will require some customization of the motor, and probably some cutting/soldering of the wires, but this would work. (See: Can 10153 9V train motor be powered by the Power Functions Battery pack?) Another solution is to add a second battery pack in ...
Here is a new cross track available from Bastens http://www.bastens.com/cross-train-track-lego-compatible.html which is more stable than building one from scratch. Cheers!
Apart from those mentioned by Joe, there are several larger sets in the Advanced Models category. They are not powered out of the box, but can be motorized. These are: 10233-1: Horizon Express 1351 pieces 10219: Maersk Train 1237 pcs 10194: Emerald Night 1085 pcs 10183: Hobby Trains 1080 pcs (This is actually for the previous train system, that used ...
Right now, the largest commercially available train is the Lego City Cargo Train, Set 60052. It comes in at about 887 pieces. There are 30 rail pieces in this kit. Extra rail pieces are also commercially available through Lego. The 7898-1 cargo train would come in second as far as piece count. Same amount of track as the 60052.
If you don't connect the two subsystems electrically, then it is quite possible to do so. The Power Functions motor will be on when it can get a signal and the 9V train motor will be on when the train runs over the metal rails. The metal rails will need to have external power attached, and you have to adjust the speed there separately. The mechanical ...
As you suspected, you cannot use the Ultrasonic sensor without an "Intelligent Brick" (EV3 or NXT). MINDSTROMS would be a great way to automate your train if you are willing to make the investment. For more ideas on how to use LEGO MINDSTORMS with LEGO trains, check out Sioux.NET.
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