WEAVERS - [Complicated DCC Reverse Loop Issue help needed]

[Chrissaf]

Pedro, your problem is that this is not a simple figure of 8. Think of it as an oval loop around the outside. Then you have 2 reversing loops (RLs) across the middle, each made up of an "A" on one side and "NO GO" on the other.

 

Easy to prove - run a small wagon around the outside loop starting at the bottom. After one loop (or many) it comes back to the bottom facing the same way.  Now go around via either of those A/NO GO tracks and it comes back to the bottom facing in the opposite direction. That's the definition of an RL.

 

How do you handle it - you need an isolated section longer than your longest train and a Reverse Loop Module (RLM) to power it. Do a forum search for these terms and you'll soon turn up some detailed instructions from Chrissaf on how these work.  He may even be typing a solution to your layout with diagrams right now. 

[Chrissaf]

Simple figure of 8 but can somebody tell me how to reverse the polarity where it says 'NO GO'

This DCC is new to me and I would like to know why there is no power.

Appologies for the drawing on 'Paint'/media/tinymce_upload/8c1b6cbba6c67627ca0688d9ea96edf6.png

[Chrissaf]

The fact that any of that works at all is amazing. I deduce that either you have fitted some Insulated Rail Joiners in the locations that you have the red arrows pointing at (but not annotated on your sketch) OR you have not fitted any DCC R8232 point clips yet.

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Given your 'No Power' comment rather than a 'No power due to a short circuit' comment then I suspect that IRJs are fitted.

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I will provide a more detailed answer with a 'Reverse Loop' solution later when I have more time available .. check back later.

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In the meantime. You can download my 'Reverse Loop Tutorial' from here:

https://btcloud.bt.com/web/app/share/invite/TVjeV58CqN

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TIP: As a newbie poster on the forum, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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[Chrissaf]

Detailed reply as promised.

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In order to resolve your issue you will need to electrically isolate the whole of the middle cross-over track section with 'Insulated Rail Joiners' [iRJs] and add a 'Reverse Loop Module' to power this isolated section.

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If this is Hornby Track then the IRJs are Hornby R920.

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/media/tinymce_upload/8cec3e2b912e36187702fa31b1712a27.jpg

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There are Reverse Loop 'rules' than must be adhered to. These 'rules' are explained in the PDF tutorial I provided the link to in my earlier reply. The only 'rule' I will highlight here is the 'rule' that the length of the RLM protected track section must be longer than your longest train (train as in locomotive plus hauled rolling stock).

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Relating this 'rule' to the above. The track distance between A & B, A & D, C & D and C & B must be greater than your longest train. Thus the IRJs need to be placed as close to the main outer loop points as possible.

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I also strongly advise (assuming Hornby track) that if not already fitted, that all the points are fitted with R8232 DCC point clips.

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Rather than expend energy and time describing the following RLM operational concepts in this reply ... read my tutorial for the details:

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• What does a RLM do?
• How does a RLM work?
• RLM trigger currents, and why they must be lower than the current the DCC power supply can provide.
• What brands and models of RLM are available and their specs.

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I will however dwell on 'Trigger Currents' for a moment as this is really important because you are using a Select controller.

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For a RLM to function, its trigger current MUST be configured to be less than the current that is available for the track from the controller.

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The Select (as standard) comes with a 1 amp power supply. Many RLMs on the market either have fixed trigger currents or adjustable trigger currents that exceed 1 amp. Hornby's own RLM [R8238] had a switchable setting to cater for the 1 amp supply, but even then the R8238 RLM tended to be tempremental using that setting.

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The R8238 is now obsolete and no longer available form Hornby, but there may be stock still on some retailer shelves. My RLM Tutorial details other brands and models of RLM that are available. Note that my tutorial was written when the R8238 was a current Hornby product, so it is documented extensively in the PDF.

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I strongly suggest that to minimise reverse loop RLM switching issues, that you upgrade your Select 1 amp power supply to the official Select P9300 4 amp upgrade power supply.

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When reviewing my PDF Tutorial section on alternative RLMs to the obsolete Hornby R8238 RLM. Do bear in mind that any RLMs that are indicated in my tutorial as needing CV adjustments to set them up, will require your Select to be at either firmware revision 1.6 or 2.0 or later. Select firmware below those revisons cannot configure the relevant CVs. Thus a RLM with a fixed trigger current at about 2 amps (using a Select 4 amp supply) will be ideal. Personally, I use the TamValley RLM which has a physical link selectable 1.7 amp trigger option. This works flawlessly in conjunction with my Hornby P9300 4 amp supply.

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This is a very long reply .. so please do not use the 'Blue Button' to reply.

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Particularly as my reply includes an image, using the 'Blue Button' will result in your reply being held back for image approval, even though it is an existing image.

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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