sjim

That's how Swedish railway signals work. https://en.wikipedia.org/wiki/Swedish_railway_signalling While I may be biased, this signalling system is one of the most straightforward I've come across. It has the option of using 2-5 lights and still gets a lof of information across.

Mine usually end up large... :)

But... This is amazing. :P I have been trying to find a good solution for a year, but the measurements are really wonky, the torque required is high and the bottom of the switches are really fragile. Thank you!

I had the same problem some time ago. After some testing I found that the wheels on the locomotive that are put in a technic fram got pushed together when driving over switches "backwards". This created a lot of friction and resulted in the behaviour you describe.

Ah, you are right of course. Did not think about that. :)

I really like the idea, and have tried to do something similar myself. For my part I don't think I would buy it. Some of it is the cost, but mostly because I would need to have two lights (A1 + B1) on at all time and sometimes three lights (A1, A3 + B2) and it seems that this could cause issues. If I were to buy this kind if product I wouldn't want to risk frying it by mistake because of a bug lighting up all LEDs. Maybe this could be solved with transistors with little additional cost? In any case I love the simplicity of it. Also, making it 4 x 4 studs is brilliant. I would also consider naming the outputs LED1, LED2... as most countries do not use signals the way cars do. Keep on programming!

I adjusted the switch to use a small pneumatic cylinder instead, and also I put pictures of the building process. Check it out and let me know what you think: http://greytag.se/lt2/pneumatic-switches/

Thank you for your interest and feedback! That is correct. Pneumatic cylinder -> 2 x liftarm (arranged in an L-formation) -> 8 tooth gear -> gear rack I tried the small cylinder, but failed. I can't remember why at the moment though... :) I'll probably have another go at it soon enough. If I had seen your pictures before I might have gone that way. It looks brilliant! I'll have a try with pneumatics one day. I found that the only way to get it done by motors was to build an enormous 'holding cage' to ensure that the power needed didn't break the construction. In the respect I have to say that baard put me to shame in a brilliant way. :) In my experience there is no way to have reliable automatic switching without raising the track. The bottom is too weak. The CAD part is not where I excel. I'll get some more photos posted in various stages of building, no problem. :)

I have long tried to make a mechanical switch for my Lego trains, but never got it to work properly. Part of this has been that the underside of the switches has been too weak. The resolution so far is pneumatic switches. You can find a video here: If you want to see some pictures and download the ldr, go here: http://greytag.se/lt2/pneumatic-switches/

Thanks! Thanks! Your video was one of my main inspirations, but I lost the link. :( Now that I have it, I will link it from my page. The short story of the funding is that Helsingborg City wanted to add a creative place to the festival. A group I'm somewhat involved with was tasked with this and a few of my friends got some funding for an AR-project (The Sandbox). This project fell through however, and I suggested to replace their project with Lego trains and got the funding. So a bit of luck and guts. :P The AR-project and an additional copy was produced and shown anyway by the same team to I got some trains, the city got three (!) projects and people got to build their sandboxes. Triple win!! http://www.creativelab.nu/program-utstallare/

Thanks! Agreed! I tried, it's on the list of iteration 2. :) Absolutely!

Some time ago a group I'm engaged in got some money to create projects for our city festival (sort of). For a bunch of reasons one of the main projects fell through and we needed a replacement. I suggested a display with Lego trains controlled by Arduino. Last week was presentation time. It's a first iteration so I wanted to make it simple yes a fit fun to look at. The trains go in opposite directions in an oval. There are two stations where the trains either wait five seconds or wait until the upcoming track part is clear. If the waiting time is up and there is no other train in the way it's go-time. Since the trains go in opposite directions, the switches can be static. You can check out a more in-depth description on my site: http://greytag.se/lt/showtime/ Let me know if you have any questions or comments.

No problem. Have fun! Don't forget to post a video so we can see your creation. :)

I am going to use north and south entrance instead of A and B as this seems to be a bit confusing. I hope that's ok. This is the easiest program I can think of: - If the north sensor is pressed --- Yes: Lower bridge, allowing trains to pass --- --- Wait for south sensor to be bumped --- --- Raise bridge --- No: Is the south sensor pressed --- --- Yes: Lower bridge, allowing trains to pass --- --- --- Wait for north sensor to be bumped --- --- --- Raise bridge --- --- No: Do nothing I have attached an image of the program. If you like, PM me with your email and I can send the .rbt file to you.

I updated the design to use a bigger arm to connect the to the trigger and now it work ok. Thank you all for your inputs!