Lego Train Electric Tower
Introduction
December 18th, 2010
The kids and I were really getting into Lego trains so I started looking around the web for what Lego train systems were available. I was hoping would be a battery-less system available. Lego did have a 9V system with metallic rails but unfortunately Lego discontinued the system in 2007. The parts were still available via resellers on the web but the used rails seem to come at a premium. Also I didn't want to invest in an obsolete system.
The new train system Lego put forward to replace the old 9V system was the Remote Control (RC) trains followed shortly by the Power Functions trains. The RC/Power Function trains used fully plastic rails with the power for the train coming from an on-board battery back. The new power function system was neat in the sense it had a hand held RC remote but I really preferred to not have to use up batteries all the time. I also didn't want to fork over $40 for the Lego rechargeable battery pack at this point because I was not sure how long the kids would want to play with the train sets.
I had some free time one afternoon so I thought I would try to put something together with whatever I could find in my workshop. My general idea was to put a tower in the middle of circular track. The tower would have some slip ring mechanism that would allow the train to continuously run around the tracks without having to worry about a cord winding up,
The First Attempt
The most important part of the tower would be the electrical slip rings. My plan for that was to try using some copper washers I had laying around. I soldered some metal plates to the washers then clamp them to some plastic threaded road to hold them in place.
For one of the two electric conductors I had to route the wire through the middle of the threaded rod which meant sawing half way through it without breaking it. I managed that and also manged to put the slip rings in place but the assembly did not work very well. The slip rings had a few bad spots in one direction which it would not easily rotate through. Also the plastic threaded rod did not make a very strong tower.
I decided the initial design was flawed beyond repair so I gave up on it and tried again.
The Second Attempt
Electric Slip Rings
For the second attempt I dug a little deeper through my workshop parts bins and found several larger copper washers. I decided for this attempt I would use metal threaded rod instead of plastic. I still used a short section of plastic rod to electrically isolate the two conductive joints needed to get the electricity from the power base to the train motor. The slip rings seemed to work much better with this second attempt.
Tower Base
For the electric tower base I happen to have an old, broken desk lamp that I had been meaning to fix for about a year. I decided rather than fixing the lamp I could put it to good use by cannibalizing some of its parts. It had a rather heavy base which was perfect to keep the electric train tower from toppling over.
Cable Boom
To extend the electric cable out over the train I wanted something relatively light but still stiff enough not to bend as it was pulled around by the train. A coat hanger did the trick.
Wiring
To make the tower easy to use with the Lego electric system I bolted some of the9V Lego electric plates to the tower and soldered the wires to the undersides.
A Little Less Ugly
I expected the home-made contraption to look like it was home-made but it was even uglier than I thought it would be. After I got the basic assembly together I thought I would try to give the tower a slightly better astetic appearance by covering it with some forest green electrical tape. It helped... a little.
Testing
Initial testing of the tower with an Ohm meter showed I had a few bad spots in the slip rings where the connection would open. When I put the slip rings together I used several layers of copper washers thinking it would make the joint rotate around the tower better. I thought those extra parts might have been contributing to the open connection. I ended up soldering a few of the extra layers of copper washers together to make the connection better and the according to the meter the slip rings were making good contact.
Action Video with Test Train
I built up a quick and dirty motorized train to try the tower out. Woody and Teddy provided the train cars for the engine to pull. The system work with no adjustments needed. Again its not going to win and aesthetic design contest but its functional.
The Lego motor dirve control box shown in the videos to the right was from a previous project.