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Hello Robert,

Thanks for your input. I saw some of your webpages before, but they keep improving :thumbup: . Using wheels from a dismantled duplo loc would work better for sure, but the design by zarli actually works very well for bridges.

P7270231.jpg?m=1379474372

(not my picture)

However, (in my case, and only if I use front wheel drive) there is not enough weight on the front wheels to drive up the bridge. Rear wheel drive or four wheel drive works like a charm.

Problems I am having are at the switches. When the train comes from the forking side, it just wants to continue straight on and sometimes derails. I think it might have to do with a lack of a differential or conical wheels. The performance also suffers a lot on the curved tracks. I see now (on your site) that the modern switches have traction ridges on both sides, which is another indication that this might be the problem. Btw, I should mention that derailing occurs more frequently at higher speeds (not surprising).

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Hi Peter,

If the long link is a problem, you could reduce it by adding an extra loop and some more track, like so:maxrun.png

Edited by Guy_Walker

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Wet afternoon so built the all important Flip-Flop (Distributor) circuit using a gang linked point.

dup41.jpg

The lower ‘converger’ piece merges two tracks together. All the black pieces are smooth (for push-along trains) but the Lego loco didn’t lose traction.

The circuit operated correctly with the train arriving at the converger upper and lower tracks alternately. This behaviour required an infinite circuit according to Adam and Greene, but they used only single (not linked) points (post #151 for PDF link).

You’ll notice the lazy points are linked with a ‘low tech’ piece of curved coat hanger wire. This works surprisingly well for a quick set up. The slight springiness of the wire seems to help. Not sure about a long link though Peter.

The problem with gang linking points under the track is the need to raise the track on bricks. This can lock the track together, which seems a good idea but without 'play' most layouts have alignment gaps and cannot be built. Maybe some kind of overhead link is the way to go?

The solid construction of a large reliable train track computer is perhaps a very different exercise, requiring glue and screws to securely hold everything together for continuous operation. A major project for another time…

Edited by Guy_Walker

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We built the layout I posted in #174 some time ago. It was all raised on duplo plates (of which you need a lot). The play in the layout is reduced by this, but there is enough left to make it fit without too much strain. We almost ran out of both straight and curved track pieces, but the layout is certainly worth the trouble. Really fun to watch! The longer link below worked quite well. There is a little bit more friction, but not too much. The longer links are useful I think, because the alternative uses more track pieces again. We would not have been able to build it.

I like your solution too, Guy. And a great layout too. I might try to get some of the older black pieces at some point. What would happen if a motorized train comes onto the converger from the other side (a diverger I guess). Would that give us a random binary number or would it derail?

16icz2g.jpg

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Cool! - long links rule! And it does save a lot of track, so they really are necessary. I’m glad you had fun with the layout.

These ‘auto run’ circuits are quite good fun to watch. You feel like you’re getting your money’s worth or something. However, I’m not having much luck with the maths, so no idea what the best (longest) runs attainable are. I think this is a maximum for 2 co-operative points.

This layout uses 3 co-op points. It might just be buildable but many of these larger circuits don't work out well with Duplo geometry. An equivalent interactive layout is on the cr31 auto run page.

3coop.png

What would happen if a motorized train comes onto the converger from the other side (a diverger I guess). Would that give us a random binary number or would it derail?

Good thinking - I did try using the ‘diverger’ piece as a random output generator. The train does not derail, but it tended to always choose the same side, so not than random unfortunately :-(

Edited by Guy_Walker

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Just a photo of the maximum run layout as described in previous posts #174 and #162. It is slightly more compact than the diagram in post #177.

Both pairs of co-operative points use short overhead links - a 4mm diameter wire bent into a 5x5 inch goalpost shape.

maxrun4.jpg

The train only just manages to complete the circuit (resetting all points) before it timed out, although I think I read somewhere on this forum that this can be disabled.

Edited by Guy_Walker

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That looks really interesting. Seeing the physical layout, it looks somewhat modular. I wonder what would happen if you duplicated everything to the left of the rightmost loop (i.e. everything from the right-hand points inclusive) and connected it in place of the left-most loop? Or perhaps replaced the right-most loop with a mirror image of everything to the left?

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Very cool layout. Five intersections though... I won't be able to replicate it. The layout in #181 is closer, but we only have 4 lazy points I think.

The wire arches do seem to be the easiest solution for linking.

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Wire arches work well if pairs of points can be held apart by a Xover.

Layout #181 has 3 pairs of points but is unusual in using so few Xovers. Larger auto switching layouts tend to have many tracks crossing each other. I think its symmetry may make it less interesting to run though.

Peter Nolan #183 -I’ll try out your ideas and report back.

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First, an update of the auto switching layout in #177, with added ‘0’ and ‘1’ labels.

maxrun4a.png

Starting at a0 with all points set to ‘0’, the train traverses the following tracks between points:

a0-c, c0-b1, b-a, a1-d1, d-b0, b-a, a0-c, c1-d0, d-b0, b-a

The complete ’tour’ takes 10 stretches of track to return both pairs of points and the train to their starting positions. So this circuit has an auto run length of 10 tracks.

Any circuit with 4 points always has 6 tracks, so some tracks are used more than once. Indeed 2 tracks are used twice and 1 track is used 3 times. All in the same direction, no track is bi-directional. Shown by chevrons in the diagram.

Also btw, entries in bold show when points are switched by the train. You can see only the lower point in each pair (B & D) do the switching. So these ‘active’ points will in theory wear out faster than the upper ‘passive’ points A & C.

I wonder what would happen if you duplicated everything to the left of the rightmost loop (i.e. everything from the right-hand points inclusive) and connected it in place of the left-most loop? Or perhaps replaced the right-most loop with a mirror image of everything to the left?

A quick diagram of the connected circuits may help.

maxrun4x2.png

The second (lower) layout is symmetrical, both circuits share a common track (b-a) and so remain in synch. This gives an auto run of 2 tours, a total of 2x10 = 20 tracks. Not a particularly long run for 8 points.

The first (upper) layout is more interesting. You are connecting a track which is used 3 times (b-a) with a track which is used once (c1-d0). This creates a kind of 3:1 gear ratio. So starting at a0, by the time the left hand circuit returns to its starting position, the right hand circuit will have been visited 3 times. So producing an auto run length for the entire layout of 4 tours (40 tracks).

Adding a third circuit to the right will increase the auto run length to 1+ (3x4) = 13 tours. Four circuits will take 40 tours etc. Each tour requires 10 tracks to complete. This is an efficient method to produce long auto switching layout sequences. However, it is not necessarily a maximum for the number of points used.

The numerical series 0, 1, 4, 13, 40… can be generated by the formula t = (3^c -1) /2

where t is the number of tours and c is the number of circuits.

Also note each tour takes 10 tracks and each circuit has 4 points.

So for example, connecting 10 circuits together will require 29,524 tours to return all (40) points and the train to their initial starting positions. My train took 2 minutes (just after timing out) to complete one tour, so just over 41 days continuous running is required to reset the whole layout!

Edited by Guy_Walker

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Nice one Guy--I admire you dedication! Sadly I don't have enough crossovers to build these layouts, but it is interesting to see them and consider how they would work.

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Very interesting. Maybe the best way to find max run layouts is by using a genetic algorithm. While not as satisfying as mathematical proof, it might be a practical approach in case of a high numbers of points.

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Yes -it’s easy to get carried away with the theory. It tends to lead to oversize layouts with far too many crossovers. But the method of joining small modular circuits together is useful in determining the behaviour of larger circuits.

cct1.png

Here is a similar but much simpler example than my previous post. Using the single circuit on the left, connect loop to central track producing a series of 2:1 gear ratios. The overall auto run length is given by:

4 (2^c -1), where c is the number of circuits (pairs of linked lazy points). So 28 in this case.

The layout also steps through all 8 combinations of its points as a cyclic Gray Code, which could be useful.

The Duplo ‘auto switching layout’ built in post #182 had an auto run length of 10. Using 2 circuits as above will improve this to 12.

I think that this construction method produces layouts of maximum length for any number of point pairs. No layout can have a longer auto run length for the number of points used. I don’t have a mathematical proof though.

cct2.png

Btw, the above similar layout has the same auto run length of 28 but the train switches 14 points instead of 8. So a harder working train. (The layout can be built without the crossovers).

I’ve updated the cr31 Auto Run page to reflect the above info.

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You keep surprising me the depth that this subject has!

Also, I realized that the layout in #182 or #186 can also be built with just two intersections and a bridge. Something to try next time the duplo trains come out :-)

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There’s quite a bit to it and multiple aims too. Good maths or good Duplo layouts :-)

Yes you’re right, you can reduce the Xovers to 2, or even just 1, but the circuit ends up much bigger. I’ve not investigated using bridges, (a whole new dimension), but they do add interest to practical layouts.

The other advantage of Xovers (besides compactness) is they help keep the track more rigidly fixed together. Especially the point pairs which makes the wire arch links more reliable. I'm not sure why Xovers are so expensive to buy though.

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I have a second hand duplo intelli train (set 3335) which does everything except respond to the code bricks. I have opened up the train and noted that there is a component which appears to be singed and I would like to repair this. However, I cannot find a circuit diagram anywhere and am not sure what the component is. This issue is also affecting the passenger train (set 3327). Can anybody please help?

Thanks,

Mike

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Wow! What an entertaining eight pages!

Glad to hear that so many adults "play" with Duplo! Our children and grandchildren don't know just how lucky they are to have access to such fine toys. And we get to enjoy our toys with them. My son only had system trains, and really enjoyed them ages 4 to 8. I have purchased a used Duplo train that I hope to share with our granddaughter aged one when she quits eating Duplo. My biggest worry is that there are so many different types of Duplo trains and track that what we build will not work.

And the circle continues...

It is fascinating to read how much theory explains how and why certain Duplo track layouts work. Now if I can get Hubby (physics engineering and can figure out anything given enough time...phew!) to focus on building Duplo instead of his N scale, maybe we can duplicate at least one of these layouts before all of the required pieces are chewed up by little boys and girls everywhere. It appears to be a race against time with the rate at which they are gnawing up the parts. Anybody care to write and videotape that algorithm? Cheers!

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Hi everyone,

Mike: you didn't buy that train off ebay in Australia by any chance? I recall seeing an item for sale that matched your description. As it happens, I have an open (non-working) intelli-train somewhere on my workbench at the moment. The problem with mine is a stripped gearbox, so the circuit board may still be OK. If you like I could take a photo of the circuit board for reference.

Legogal: I'm pretty sure that all the different types of Duplo track fit together. I think that the main problem is that with the different lengths making a closed layout can be a bit tricky. On the other hand, having a variety of different length straight tracks gives you more flexibility.

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Hi Peter,

Yes! I actually did buy it off EBay Oz. my grand-daughter will love it like it is but my compulsive obsessive disorder wants me to fix it!!! A photo of the top circuit board would be good. Especially of the three legged component next to the resistor.

Thanks.

Mike

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Hi Mike, I think that component is actually an infrared transmitter or receiver. When you connect a smart carriage, it communicates with the engine via infrared. Will snap a photo when I get a chance...

BTW presumably you are in Australia. If so, I'd be happy just to post you the circuit boards as spare parts--I suspect the chances of me doing any repairs on my engine are slim to none...

Edited by Peter Nolan

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Hi Peter. That's what I thought it was but wasn't sure. Yes, I am in Australia! If you really don't want the boards, of course I would accept them gratefully. Can I give you something for them (and pay for the postage of course)? I have a postal address to which you could send them. Regards, Mike

Edited by fireman08036

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Mike--I tried to send you a PM, but it failed for some reason. If you send your details to me by email or PM I'll organise postage.

Cheers,

Peter

Edited by Peter Nolan

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Just a quick photo of the auto-run layout described in my previous post #189. It is the first (upper) circuit, but with just 2 stages instead of 3. Each pair of points is linked with a wire loop as usual.

maxrun13.jpg

It has an auto-run length of 12, which took the train 1 minute 23 secs. More stages can be added, with each additional stage more than doubling this time. Unfortunately the train times out (auto stops) after 2 minutes, although the electronics can apparently be modified (post # 170).

Edited by Guy_Walker

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Guy these layouts are what I have been searching for. Do you know of anyway to link the switches with blocks. Just looking for something that I can use with my kids on their sets.

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