Wiring help with fiddle yard throat

[paul.b]

Hi all i have bought a made to order fiddle yard throat which is all insulfrog (see pic) the problem i have is the tracks keading to the throat come from the main but from different directions so when the meet at the throat the negitives are next to each other ( see pic) am i going to cause a short if so is there a way around it i just cant get my head round the wiring 

 

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[Chrissaf]

You posted this in the DCC sub-forum, which would infer that your layout is DCC, but I have not assumed that in preparing this reply.

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The triangular section of track in your design is called a "WYE reverse loop" and YES it WILL create a short circuit.

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How you deal with this, depends upon whether your layout is DC Analogue or DCC Digital controlled. In either case whether Analogue or Digital, the WYE section will require strategic placement of Insulated Rail Joiners (IRJs) in association with a track polarity switching arrangement.

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If analogue, then you need a mechanical track polarity switching arrangement. Google WYE Reverse loops and you will find some options on how to do this. If digital, then you can use a RLM (Reverse Loop Module) to deal with the whole short circuit problem automatically and in real time (still needs the IRJs fitted).

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This previous question and reply fully details the WYE issue on an Analogue layout. It explains how the short is created and some options for dealing with it.

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https://www.hornby.com/us-en/forum/layout-advice-please

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If your layout is DCC, then here is a link to my PDF "RLM Tutorial" document which covers DCC reverse loops in great detail.

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https://btcloud.bt.com/web/app/share/invite/ubIhRds4Ym

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Note: when you click the RLM Tutorial link that appears on the linked page above. Depending upon how your browser is configured nothing may appear to happen. Just check your nominated browser download folder and you will more than likely find my PDF document has downloaded silently in the background.

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There is potentially a second Reverse Loop present in the fiddle yard. Which is the one your posted query relates to.

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This will more than likely create a secondary short circuit. The reason I am being hesitant to confirm one way or the other is due to the complexity of the custom throat points configuration. If it does indeed create a reverse loop short circuit, then it will be in the form of "Fig 16 - Example Layout WYE Loop 2" on page 28 of my downloaded PDF doc.

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If your layout is DCC, then you will need to deal with both potential reverse loops individually. This will probably involve installing two RLMs. This is going to be very awkward, because with your current layout design, both reverse loops are adjacent to one another without any static DCC reference track in between. This will break Rule 3 in my PDF document - see Section 5.3 on Page 17. This can be overcome by inserting a couple of straights in the long fiddle yard loop that are connected to the main DCC BUS - see Page 18 in my doc.

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When wiring the middle custom throat point section and connected fiddle yard tracks. It is very important to maintain the same rail polarities consistently throughout the middle light blue section. In other words, ALL the light blue lower rails connect together and ALL the light blue upper rails connect together before being connected to the output of RLM 1. In this context, upper and lower as being a reference to the drawing above. More details on this can be found in my document on Page 29 & 30 in the text relating to Fig 18.

[paul.b]

Hi chrissaf thanks for the reply iam indeed dcc i have bought 2 hornby dcc reverse loop modules to fit i will have a look at the pdf 

thanks pebo

[Chrissaf]

Pebo, bumping this post to bring to your attention further edits of detail added to my reply since your your last post above.

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Pebo, you are the first forum member other than the other Mods and Adam to see my "RLM Tutorial PDF". So I would really appreciate some feedback on whether it was informative or not. The intention is to continue to push Hornby to publish the PDF on the forum as a permanent fixed download link similar to my existing 'Getting Started....PDF".

[paul.b]

Hi Chrissaf thanks for the diagram all my points are electrofrog exceot for the purpose built throat it is all insulfrog will this make a differance to the two RLM also the two entrance track to the fiddle yard will have the negitive next to each other (   +  -   - + ) 

[Chrissaf]

See my last paragraph edit to my earlier reply regarding wiring the throat points. Using Electrofrogs on the rest of the layout will (should) not impact negatively.

[paul.b]

Hi Chrissaf i have uploaded a pic of what i think i need to to its a bit of a crude drawing but i think you will get my meaning  and am i correct in my thinking /media/tinymce_upload/919960695f6885d650cabcc7ee714261.jpg

[paul.b]

The PDF was very helpful it was easy to understand how the RLM works and where the isolated rail joiners go i used it to figure out the post with my layout pic with the coloured lines 

[96RAF]

Those twin double slips appear to be electrofrog as I cannot see any plastic in those areas at all I.e. on the left end of the top picture - fiddle yard end in the 3D.

Rob

[Chrissaf]

In principle, that compares well with my more conceptual drawing. You might want to move the two black sections on the fiddle yard loop slightly more over to the left. So that the track length of the green track compares more equally with the blue track lengths to where they meet with the main layout on the right. In other words, make the distance a train travels on the green section match the distance the same train would travel on the bulk of the blue track.

[paul.b]

Hi Chrissaf

the total length of the fiddle yard loop from main layout back to main layout is 300 inches so are you saying i should make the green section 150 inch and the blue section of the loop 150 inch or do i need to take into account the fiddle yard as well 

 

thanks pebo...

[Chrissaf]

If you make the green and blue sections 150 inches each less the length of the black track sections. Then that means you can maximise the length of a train (loco plus hauled rolling stock) to close to 150 inches too. 150 inches being 12.5 feet = 3.8 metres which should be long enough for any rolling stock you that you might want to run as a train.

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The length of the fiddle yard sidings is not an issue, because being sidings they are dead ends and I assume that they will be longer than any length of rolling stock that you might want to park on them.

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The sidings being dead ends means that they do not provide a transit route through the fiddle yard back onto the layout somewhere else, or onto the fiddle yard return (reverse) loop. Thus they are less significant from a RLM design point of view.

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In my last reply I wrote:

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"In other words, make the distance a train travels on the green section match the distance the same train would travel on the bulk of the blue track."

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Given your clarification query above, then maybe my text would have been clearer if I had wrote this instead:

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"In other words, make the distance a train travels on the green section match the distance the same train would travel on the 'through route' blue track sections, excluding the fiddle yard sidings"

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In other words try and make the section of track indicated by my three red arrows all the same length as far as you can by positioning the intermediate black track sections as appropriate. Remember the black sections only need to be longer than your longest piece of rolling stock, so they can be relatively short. Say about 350mm.

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As you can see in the drawing above, the green track section looks to be a lot longer than either of the two indicated blue track sections. By moving the intermediate black sections slightly to the left, then all three indicated track section lengths can become more symmetric (length wise). Maximising the overall train length that can be accommodated.

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PS - No reason why the black sections need to be straight track lengths, they can be part of the curves of the fiddle yard return  loop.

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You might want to post an image of the WHOLE layout (some of it is currently cropped off screen in your last posted image). Then I could assess if there are any other reverse loops in the unseen part of the layout that you might have overlooked.

[2e0dtoeric]

AS an aside to the topic - where did you get that nice space-saving piece of track-work from?

[paul.b]

hi Ericm0hff i got it of ebay here is a link to the guy that makes them he can make them to your track plan

 

www.ebay.co.uk/itm/153198149102?ViewItem=&item=153198149102

[paul.b]

here is the layout chris/media/tinymce_upload/bfa3d4cdf8de891592203f684cb80037.jpg

[96RAF]

I thought at the start of this thread - ‘thats going to be a few quid’. I wasn’t wrong.

Rob

[paul.b]

Hi Rob

yes a few quid is right but realy it cost me nothing as i won a few hundred on a scratch card and thought why not   😀 she who must be obeyed knows nothing  😛 if she knew i had won i would have been mugged as soon as i stepped through the front door

[96RAF]

If you look at the costof the basic elements and factor in the conversion work then I reckon its not overly expensive -relatively.

I baulked at nearly £30 to post it to Cyprus.

[2e0dtoeric]

Thanks for the link, Paul.

[paul.b]

Your welcome Eric...thanks guys for all your help think i have got my head round this wiring so had a play last night with trying to represent this on Railmaster ready to try when i fit the point motors. I had a look at the double slip plan in railmaster but cant understand all the coloured circles and what they mean. Being that  the throat is two double slips and two three way points i cant seem to plan it on railmaster where it looks anything like the throat 😢  

[96RAF]

The only sensible way to plan it on RM is to represent the doubles and three ways by using singles left and right in sequence. It won’t look the same and will take up a lot of plan-space but the operating logic will be there. Good luck with the RM double slip - it has been covered in the forums before As people struggled to get the firing correct.

 

The circles are the point ‘operating buttons’ and need to be dropped onto the centre of the point on plan to correctly lock into place. Each set of buttons needs to be right clicked and set up to ackle as required and this is where the double slip complication arose previously.

Rob

[Chrissaf]

RM track plan is a logic diagram. You will never get it to look like an accurate representation of your custom throat point configuration. As Rob says, each element of your points will take up at least an individual square in RM or more than one square (double slips & 3 way points for example), so the overall representation of your custom throat is going to take up a lot of RM track plan space.

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If Ray sees this supplementary question, he might draw up an example in RM that would probably work and post an image of it back here. He has before in replies to similar 'How Do I' in track plan type questions.

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Also, you might need to upgrade to RailMaster ProPack (if you haven't already) to access the additional ProPack point symbols that are available in it.

[paul.b]

Hi Chris

I have railmaster pro the coloured circles i was refering to are the dark blue and black ones that appear as you fire the points in railmasters double slip plan. Also i was going to setup the throat logic plan in the middle of my main layout plan  as there is lots of space on screen to fit it in 

[Chrissaf]

For the information of the forum membership:

See new thread started in RailMaster forum for a continuation of this RailMaster track design query

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https://www.hornby.com/uk-en/forum/how-would-i-design-this-in-railmaster-pro-/?p=1/#post-264427

[Chrissaf]

Hi Paul, I like the dropped river crossing scenic addition. No other reverse loops that I can see that are in addition to the ones already previously discussed.