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[chadnn]

Hi all,

I'm planning on doing this layout: http://www.scarm.info/layouts/track_plans.php?ltp=61 minus the sidings for now.

Will be running two trains so plan on having 2 blocks, block 1 starting at the west end of the station going around to the east end, then block 2 starting there and going back to block 1. Being old and simple minded how do I wire this? To make it easier for me to understand, lets call the train closest to the station #1 and the outside train #2.

So train #1 is going to head west from block 2 into block 1 and train #2 will move east from block 1 into block 2. Have 2 PWMs but not sure how to do simple wiring to make it work.

Thanks for the help. Pictures would be a great help too.

[dkightley]

Having looked at the layout, I can see that the basic track plan is virtually the same as The Bridge....ie basically a loop. And simply splitting the track into two sections and having a PWM controller powering each section is not that good an idea on its own without adding some form of isolation section between the two powered sections.

The basic problem is when a power car passes over the gap between two sections, because both bogies pick up power, the powered unit will connect the two track sections together for the time the unit straddles the gap in the track. This is likely to cause havoc with the controllers and might even damage one or both controllers.

The solution is to split the track loop into four sections...your track#1 and track#2..with a short track section in between each of the joins. You can then put a switched supply to each of the in-between sections that connects the section either to track#1 or track#2...and then you will need to manually flip the appropriate switch to change over the control from one PWM to the other. If these two short sections are hidden under scenery, then the viewer will not see any stop/start or speed change as the switches are flipped.

On The Bridge and martinK's Sarum Bridge the need to manually flip switches goes away as we both have a cpu driven controller (or Martin's design!!) that controls three trains chasing each other round the loop...a fantastic system that has me (and visitors who see the layout at shows) mesmerised watching it!

[chadnn]

OK, I understand that. So here is what I would have:

Block 1 would be at the station for train #1, the block just a bit longer than the train. Block 2 would be the loop going west. Block 3 would be at the station for train #2 and block 4 would be the loop going east. Right? So with both trains stopped at the station I would power up blocks 1 and 2 with cab A for train #1 and blocks 3 and 4 for train #2 with cab B. If that works great. However......

What if I didn't want to stop at the station? Or if I wanted to run train #1 with just cab A and train #2 with just cab B? BTW I'm running the HST with 3 power units (each end and middle). Maybe I could get Martin to sell me a CPU

[chadnn]

Upon looking around the internet I think I found how to wire 1 cab for each train. If I understand it correctly I would take the wires from cab A and run them to the bottom posts of a dpdt switch. Then run wires from cab B to the top posts. The wires from the track go to the center posts. I would do this for each block. So if I had all the switches for cab A open then just train 1 would run. And for those of you that might remember the TV show The Addams Family, I could run each train in opposite directions and have them run head-on into each other.

Now would you do a common rail or two rail hookup? And would telephone wire work, I have rolls of it.

Thanks again!

[martink]

As Doug has been saying, setting up a block system on a single track / dogbone layout like this has more than a few potential pitfalls and complications. Also, size - it works well for layouts like The Bridge & Sarum Bridge because each track section is 4m-5m long. More than one train can be moving at the same time, while on a smaller layout each train has to take its turn to shuffle forward one section.

That's why most people go for a plain double track scheme with two controllers, keeping the two lines completely separate. My new one will have it both ways - double tracks, each with its own block control, and with some additional size-related refinements taking advantage of the visible and non-visible sections.

A year or so ago, Ozrail was playing with a really sneaky scheme to use the standard Eishindo PWM controller and its two sensors to have two trains following each other around a layout similar to yours, but I haven't heard anything more about it. One train stopped in the station until the other was about 2/3rds of the way around, then it started, then the other took its place at the station. That only required the standard kit, half a dozen diodes and two isolating track pieces. However, there were two potential drawbacks: the sensors really needed to be mounted at an angle to the track to ensure reliable train detection (possibly requiring a bit of surgery on the sensor base and the piece of track), and the diodes cause a noticable voltage drop and hence poor low-speed running.

The key is deciding EXACTLY how you want your layout to run. If you are planning to fit the points at a later date, then just having a isolating section for each loop lets you manually select one train to run.

For one of your other questions, if you do go for a block system then I would probably recommend against using common return. Its main purpose is to reduce the amount of wiring needed for a large layout with dozens or even hundreds of sections, but the advantages are minimal for a smaller design. However, since the controllers are battery powered, it would work fine. Six of one and half a dozen of the other.

[chadnn]

Thanks guys,

My layout will be 6 ft by 3 ft so am thinking each block will be about 7 ft long in 28-30 ft of track. Still short yes but I think doable. I'll just be flipping switches a lot