How to Make 9V and 12V Lego Train Tracks*-* Click images for Huge Pictures
Intro: Make Plastic Lego Train Tracks Backwards Compatible with 9V and 12V Tracks
If you grew up in the last 15 years you know that the coolest Lego set to have was one of the Lego train sets. After all, what Lego city was truly complete without having something that could mow down any unsuspecting citizen on command? So if you succeeded in owning one as a kid, or recently purchased one on eBay for some outrageous sum of money, you'll know that the track is selling for nearly as much as the trains are! The new trains are now battery powered and therefore don't require the electrified rails like the old 9V and 12V trains do. The new tracks are identical to the old 9V track, except that it's missing the electrical conductors - so I'll show you how to very simply and very cheaply modify the track to make it backwards compatible!
*** I'm not currently fortunate to own any of the fancy switch track or cross track, it should not be hard at all to make this work on those as well, just mind the polarity and make sure you pass power across the rails to the inner track is powered as well as the outer, you can use small pieces of electrical tape to prevent shorting at the junctions if necessary***
Step One: Supplies Needed
The only supplies you'll need are Lego track and some foil tape. (if you don't want to use real track, there's another method here using 'O' gauge model railroad track that looks like a lot of work) The foil tape can be had at any real hobby supply store or stained glass shop. This foil tape is actually meant to be used between pieces of glass and then soldered together. If you don't want copper colored tracks you can buy stainless steel or aluminum foil tape (I don't mind copper tracks, but I'm sure others will disagree). I have found aluminum "flashing" tape at hardware stores, if you have a lathe or infinite patience you can cut this up into strips the correct width and then you'll have silver track. Otherwise stainless steel foil tape looks common online, I haven't ordered any but you can certainly look around.
New All Plastic Lego Train Track
***A note on the tape - I purchased mine from "Hobby Lobby" at ~$6 for 36 yards (7/32" wide) of copper strip. This tape has an adhesive on one side and is plain copper on the other. The important thing is that you get the cheap stuff and not the heavy adhesive or black/silver backed tape, as it will not conduct if you need to tape a section to another section (as you'll probably have to do for switch tracks, etc) I know this foil is also sold without adhesive, so make sure you get the correct stuff! ***
Step Two: Check out the Track and the Train Motor
The first step is to take a look at what the authentic tracks look like and how the train interacts with the tracks. As you can see below, the track just snaps together and has small tabs on the inside of the track to conduct the electricity from piece to piece. The new all plastic tracks have all the same features, just not the metal rails.
Next note how the train motor picks up electricity. It only interacts with the edge of the very inside of the tracks. So really all you need is to make sure that your foil lines the inside edge of the track and has a tab at each end for connectivity!
Step Three: Get to it!
Alright, now for the easy part. The conversion is really easy, all you need to do is peel off the backing on the copper and lay it on top of the track. Be careful when peeling the backing off, you'll want to keep the copper unbent and flex the backing only to prevent wrinkles, I found you can "push" the wrinkles off the track but you're better off not creating them in the first place. As far as a strategy goes, I found that if you lay the tape diagonally so that it has the most hanging off at opposite ends for each connection tab it works best. As far as smoothing it out, start first by running your finger over the top of the track, then go to one side on the back side of the connection tab and fold over the end moving towards the connection tab on that side of the tracks. This causes the extra tape to be pushed to the connection tab on that side for maximum contact area. I'm sure you'll figure out a good strategy after the first piece. The best part about this is if you decide later on you don't like it you've done nothing to the tracks, it's as simple as peeling the tape back off and it's right back to normal!
Step Four: Testing
Now you should have your first piece taped up and ready to test. I found that hooking up the power blocks to a stock piece of track works best, but there isn't any reason you couldn't get it to work with the taped tracks. All my tracks worked perfect on the first try, if you have trouble you can always check for continuity/resistance with the voltmeter to make sure it's connected or just peel the tape off and try again.
Step Five: Troubleshooting
One thing I had trouble with was the copper getting all wrinkled up when I tried to peel the backing off. I got it down by about the 3rd time, but if you have trouble the best bet is to take a plastic handled tool and run it along the top and inside corner of the track. If you push in one direction you can easily push all of the wrinkles out. If you have any other problems you can always remove the tape and start over. One thing to note, if you end up being lucky enough to have cross track or switch track make sure you pay attention to the polarity of the rails and don't let opposite polarity rails touch each other! You can easily use a tiny piece of electrical tape to insulate the foiled rails from each other, and you could potentially build better rails than Lego created as a result, because you won't have as many breaks in the track.
Let me know if you have any questions and I don't belong to any Lego train forums so make sure to post this for everyone else!
Now hopefully the price drops on eBay back to sane levels :-P