My Story on Electronic Device for creating loops

About 15 years ago, I wanted to build a layout where the trains went about the layout in some sort of a random fashion. I wanted a device which would make the turnouts switch between 'green' or 'red' based on some pattern which was not controlled by human hand, and make the train continue onto a track which was effectively chosen by random choice.

And so I built myself an analog electronic looping system.

I did some research using 555 timers and capacitors and resistors, and built a switching electronic device for looping through 6 relays on an electronics board. In practice, a relay would be by way of example in the open position for about 30 seconds, and then closed for about 30 seconds, then open again for 30 seconds, then closed again, etc., in a continuous loop.

Next, I connected a Marklin 5146/5147 Circuit Track through the relay to activate either the 'green' or the 'red' of a turnout, depending on whether the relay was open or closed. I placed these circuit tracks just in front of the turnouts on the layout.

So, a train approaching a turnout would first trigger the circuit track, and then this would activate either the 'green' turnout position or the 'red' turnout position for the turnout, depending on whether the relay was open or closed.

This was fun, and worked very well, so I designed and built a Marklin M-track layout with signals and turnouts to enable the random process to work.

Johns Random Marklin Layout

You can watch the video, and watch how the trains trigger the circuit tracks and switch the turnouts ahead in a seemingly random fashion. I used to watch this layout for hours and hours, watching to see whether patterns repeated themselves, and whether artificial randomness on the layout had been achieved.

In the foreground of the video, you can see the electronic board with the 6 relays switching away based on the 555 timer and the capacitors/resistors.

Excellent! I need to understand the world of 'random control' better!

At the moment I'm putting in a 6600 controller which will give me analogue shuttling, pausing, controlled acceleration and braking (with a bit of effort) but it is a long way from being random!

Only use locos that do not have decoders when using a 6600. The reversing pulse it gives will destroy any decoder, even the earliest Marklin ones.

Nice! I use the same kind of "fishbowl" apporach in my control.
Instead of homemade electronics, I use a couple of industrial PLCs, and the "magic" is in the software.
It is indeed SO interessting to watch it working, that I spend hours running the trains and tweaking the system, instead of building the landscape decoration...


(The random numbers I use is a copy of the BIOS code of the pseudo random number generator of an ancient ZX Spectrum, but when you factor in the time, I believe you can get a truly random number.
I also use detections for sorting out the trains; slow, fast, long, short, passenger, freight, etc, in order for the PLC to random decide how to treat the trains, and where to send them, so that it makes sense, according to their type...)