This is now working on an oval with two blocks. A locomotive on its own will continually run around. When attaching cars making the train longer it will stop when the last wheelset is still in the previous (read next) block.
As the relays are 24vdc and the track ac I have included a bridge rectifier in line with the coils. One relay is a two-coil DPDT type, the other a "normal" DPDT.

This works in one direction. Ideas and or comments are welcome.
Cor

Hi Per, I am sure it is not the easiest drawing to study but pls. allow me to explain.

Firstly I am an old retired mechanical engineer, not electronically trained so this drawing I made in AutoCad.


What you are looking at are two dc relays (so the bridge rectifiers are to adjust ac to dc) and rail sections that form part of two blocks.

The lines are continual and dotted because I am using cat5 cable code to connect block to block

So, the first Blue dotted line to the relays of the previous block has the same function as the Blue dotted line of this block, they are connected to an insulated section of the track in the block to registrate the (last) wheel of a train. That way a train is not limited to the length of a block. Like in real a train may cover multiple blocks, but I digress.


So, for as long as wheels are in that block section the relay is activated by receiving - from the track thus powering the bridge rectifier, disconnecting the feed to the insulated pukos so a train will stop there. The Yellow lines are the + and - ac feed to the 3 rectifiers, the dc poles are connected to the coils of the relais. When the rectifiers receive a - they will feed dc to the coils. This also means that for as long as the block is occupied the latching relay has changed.

Now, the continual Blue line is connected to a switch in the puko area (24994) and you may now see that this will cause the latching relay to go back to its original position, disconnecting the puko feed so any train following will stop. When the last wheel has left this block the Green lines will be disconnected because the Blue dotted line has lost the - deactivating the coil. This means that a train in the previous block may now enter this block.

I hope this helps. If you have a digital controlled layout this will be of no interest to you, I understand that. But I am still happy you asked your question. My next bit to experiment is to use the free contacts of the latching relay for the Green/Red lights of the signal post... Not to mention a PCB layout to solder these components onto

I will post some pictures of the bits and a little test video of a circle with one locomotive

All the best and thanks,
Cor

Edit:
As the video is too big for this site I ‘ll post it on Facebook page instead
C.

Edited by user 23 August 2024 09:17:48(UTC)  | Reason: Not specified

OK Goofy. but the solid Blue line goes to the switch track 24994 putting the latching relay back

Please, as I am not an electrician but do have an understanding of it, if the sketch has mistakes do outline those with Red circles and instructions as where I go wrong and I will digg deeper to sort it out, hoping that when it works reliably others may have use of it too.


Thanks for your comment,
Cor