Triangle reverse loop problem.

[Anrew]

I'm very new to DCC control, just got back into modelling after 30 years.  I'm building a 009 scale layout around my loft and have a triangle to get in and out of my station and yard off the main round the room line.  I wired up the third side of my triangle today with a Gaugemaster reverse loop module and on testing, at one end of the triangle I get a momentary short on the points, the points at each end have Gaugemaster frog juicers and both rails at both ends have insulated joints. Any ideas? Thanks in advance. 

Edited August 2, 2019 by Anrew

[WIMorrison]

Andrew,

 

can you give us a drawing of what you are doing and show how it is wired up please, that will ensure we are looking at the same thing?

 

Secondly, have you come across the 009Society yet (http://www.009society.com/) - well worth joining and then there is NGRM Online (http://ngrm-online.com/forums/index.php) which you will find very friendly and helpful.

 

You will from my signature block why I know about these

[BoD]

Does it affect train running?

Don’t these devices rely on momentary shorts to work?

[Nigelcliffe]

As Iain says, a diagram is needed.   However, the questioner mentions two auto-reversing devices onto the same track - "frog juicer" and "auto reverser".   Its quite possible that there is a race-condition happening with the "wrong" device tripping.  Having two automatic short-circuit devices onto the same bit of track can lead to interesting problems. 

[Anrew]

Thanks for your replies so far, not sure if my schoolboy drawing will help much, but the short only occurs when a train is going over Point A from the direction of point B. Every other movement is fine. When the short occurs the overload alarm on my controller bleeps for half a second or so, train movement stops, then restarts when the alarm stops.

[russ p]

I've got a triangle, it's a double track one so its has two reverse loop modules. 

I need to move the modules to a the longer leg of the triangle as if the train is longer than than the isolated section it trips the system when the joints are bridged. 

Its only with very long trains  so I'm in no massive hurry to sort it out 

[RAF96]

Much will depend upon where A, B and C lead to relative to existing ‘polarity.

Edited August 3, 2019 by RAF96

[Anrew]

20 minutes ago, RAF96 said:

Much will depend upon where A, B and C lead to relative to existing ‘polarity.

A and C are on a full loop of the room, B leads to a dead end.

[Luke Piewalker]

http://www.gaugemaster.com/articles/guides/Reverse-Loops-part3.html

 

This suggests connecting beyond A to the Isolated section, rather than B.

[Grovenor]

You don't need a reverse loop module for that, just isolate all 4 rails at the frog end of point B and switch the polarity of the B dead end with a relay driven from the setting of point B.

Rgds

[Anrew]

1 hour ago, Luke Piewalker said:

http://www.gaugemaster.com/articles/guides/Reverse-Loops-part3.html

 

This suggests connecting beyond A to the Isolated section, rather than B.

That seems to have done the trick, many thanks, Luke.

[DCB]

Probably easier to have the B stub as the change polarity section rather than the A-B chord

Edited August 3, 2019 by DavidCBroad

[Phil S]

As Keith suggested - an Auto reverser is NOT required for this kind of trackplan:

The tracks at A and C onto the triangle should be isolated on BOTH rails.

POWER to B is changed via a DPDT Relay (OR extra contacts on the switch controlling the points A and C together**)

(**this may depend on what type of point motor you are using, or whether you use DCC to control the points)

 

Uhlenbrock make small accessory decoders with changeover relays - 2 models  

1 with 2 independent SPDT relays and 2 addresses (any address - not compulsory to be adjacent - learnt by push button)

the other with a paired /DPDT relay and 1 address.  

I use this technique [at EACH END of a helix connecting 2 levels] - and at each entry/exit I have such a triangle - the POINTS determine which way the power NEEDS to be applied .... so the relay uses the same address, and switches to match.

(In my case, they are each on separate boards - but if on the same board, you may be able to physically combine the switching.)

[WIMorrison]

On 03/08/2019 at 10:47, Anrew said:

Thanks for your replies so far, not sure if my schoolboy drawing will help much, but the short only occurs when a train is going over Point A from the direction of point B. Every other movement is fine. When the short occurs the overload alarm on my controller bleeps for half a second or so, train movement stops, then restarts when the alarm stops.

 

Andrew what you have drawn will work however the leg you have drawn it on needs to be longer than the longest train you have.

 

a more elegant solution (only because this is what I use  ) is found here

 

https://dccwiki.com/Reverse_Sections

 

the one thing I would say is use an auto-reverser as they remove any need to remember to throw switches and if you don’t need Railcom or occupation feedback you can get one for around £25