Road Stone Posted October 24, 2009 Share Posted October 24, 2009 G'day All, Building a new layout in the New Year and compiling all the bits and bobs now. Going to use a CJ Freezer plan as a guide with a large reverse loop in it which I rather fancy. I use the Elite and am about to purchase a reverse loop module. Appreciate if any body can highlight any issues involved? Ie I'm assuming that there is no need to isolate any part of the track work etc as in DC. Cheers, Jerry Link to post Share on other sites More sharing options...
RMweb Premium BR60103 Posted October 24, 2009 RMweb Premium Share Posted October 24, 2009 Jerry: You need a section that is insulated at both ends in both rails. Ideally, it should be longer than the longest train that will run through it. Unless there are other considerations, it should run from the frog of the point that defines the loop back to the other side of the frog. The reason is that the black box that controls the loop will flop every time it is shorted. When the train enters the section it will flop, if required, to match the polarity of the main layout. When the loco reaches the other end of the section a new short flops the polarity the other way. If a car with metal wheels is still entering the section, it will flop back. Each set of metal wheels will flip and flop the section until the train is all in. If there is a wheelset over the gaps at each end at the same time, there will be a problem. If you have other tracks running off the loop -- spurs or even main lines -- it may be necessary to include at least the turnout defining the track in the reversing section. It is also possible to use the point motor's extra contacts to reverse the polarity, provided they change over fast enough. Link to post Share on other sites More sharing options...
noiseboy72 Posted October 24, 2009 Share Posted October 24, 2009 The Hornby reversing module works fine. I have used one on my layout without problems. The module has a swtich to set the sensitivity - Select or Elite. Ignore the instructions and use whichever settings work best in terms of not tripping out on shorts. The module has it's own overload protection that can trip before the controller. Link to post Share on other sites More sharing options...
Road Stone Posted October 25, 2009 Author Share Posted October 25, 2009 "Ignore the instructions". Love it! I have a reverse module on the way. So the entire loop has to be isolated. Does the power have to be conected by a seperate feed of does it go live when you switch the points the train is entering from? Hope that makes sense! Cheers, Jerry Link to post Share on other sites More sharing options...
RMweb Premium BR60103 Posted October 25, 2009 RMweb Premium Share Posted October 25, 2009 The reversing section will be completely isolated from the rest of the layout. From the main power bus, 2 wires go into the module and 2 wires come out to power the reversing loop. Any reversing loop in 2-rail requires 2 pairs of gaps in the rails. A quick sketch of the loop with 2 coloured pens will show why. Link to post Share on other sites More sharing options...
Road Stone Posted October 26, 2009 Author Share Posted October 26, 2009 Right! The lightbulb has come on now. Thanks, Jerry Link to post Share on other sites More sharing options...
Adrian Wintle Posted October 26, 2009 Share Posted October 26, 2009 Another thing to consider: If you want the reversing loop to be fully hands-off, with the exit over trailing points that are permanently set for the entry track, you will have to have an insulated frog so that you don't get a short when the exiting train hits the frog. Adrian Link to post Share on other sites More sharing options...
Road Stone Posted October 27, 2009 Author Share Posted October 27, 2009 Okay, so a normal insul frog point will do I take it? Am using Peco 100. Link to post Share on other sites More sharing options...
Adrian Wintle Posted October 27, 2009 Share Posted October 27, 2009 Okay, so a normal insul frog point will do I take it? Am using Peco 100. That should be fine. Adrian Link to post Share on other sites More sharing options...
Brian Posted October 27, 2009 Share Posted October 27, 2009 Hi My web site shows the basic wiring and IRJ placement needed for a DCC auto reverse module, if it helps? This link should take you directly to the item Reverse Loop Module If you're not taken directly to the item use the sub menu's hyper link titled "Reversing Loops" at the top of the page. Link to post Share on other sites More sharing options...
Road Stone Posted October 29, 2009 Author Share Posted October 29, 2009 Thanks guys for your help. I can only now give it a go when I start the layout. Brian, I have your web site on my favourites. It must have taken some time. Thanks again. Cheers, Jerry Link to post Share on other sites More sharing options...
Rick White Posted October 31, 2009 Share Posted October 31, 2009 Hi My web site shows the basic wiring and IRJ placement needed for a DCC auto reverse module, if it helps? This link should take you directly to the item Reverse Loop Module If you're not taken directly to the item use the sub menu's hyper link titled "Reversing Loops" at the top of the page. Hi there Brian : I agree that your DCC website is terrific, thanks. Scanning the information you've provided I came across the section on Overload Current Protection. I'm intrigued by the use of car lamps for cheap protection. What i can't seem to understand is what the lamps are doing when a short occurs on the tracks. Are the lamps always lit or only when a short occurs? What are they doing to protect the trains? Could you explain this please? Thanks and best regards, Link to post Share on other sites More sharing options...
RMweb Premium BR60103 Posted October 31, 2009 RMweb Premium Share Posted October 31, 2009 Rick: The lamps should only be lit when there is a short or overload. In DC operation the resistance of a motor is high enough that it provides most of the load and the lamp doesn't light. A direct short makes the lamp take all the load. A number of locos (Hornby Dublo ones especially) can cause the lamp to glow and even shine, impeding train running. I don't have DCC handy to experiment with. Link to post Share on other sites More sharing options...
Nigelcliffe Posted October 31, 2009 Share Posted October 31, 2009 Scanning the information you've provided I came across the section on Overload Current Protection. I'm intrigued by the use of car lamps for cheap protection. What i can't seem to understand is what the lamps are doing when a short occurs on the tracks. Are the lamps always lit or only when a short occurs? What are they doing to protect the trains? The lamps are current limiters. In normal use they are un-lit, only light when a short occurs. They work because lamp filaments are low resistance when cold. And they stay cold when the current flow is below a certain value. In normal running, the locomotive draws perhaps 200mA, this is hardly anything, so the bulb stays cold and low resistance. However, if a short occurs, there is the potential to send the entire command system's current through the short (typically 3A to 5A). The bulb will go to full brightness at around 1.8A, and then presents a resistance to the current. This means that the voltage drop occurs over the bulb, not at the short. The typical way to fit the bulbs is to use one bulb in the supply line to a large section of track (eg. the Yard is one section, the main line another, the fiddle yard a third). That bulb will current limit faults to the section, but even if illuminated, won't have any affect on other sections fed via other bulbs. What are they doing to protect trains ? Answer - they limit the maximum current to around 1.8A to a section, and they mean the voltage across a fault is very low when the fault has occured (so a short should no longer be capable of melting a plastic turnout crossing, whereas 5A at 16V through a short could easily melt plastic). Note that the bulbs mean the command station itself will NOT cut out. The command station just sees a load of 1.8A, which is a normal output. ( Some command stations which cut very very quickly might still cut out. Eg. the Dynamis has a reputation of cutting out incredibly quickly ). There is lots of debate about whether the bulb approach is "sensible" - one important point is to ensure that the bulbs are adequately ventilated; they will run quite hot when illuminated. Link to post Share on other sites More sharing options...
Rick White Posted November 1, 2009 Share Posted November 1, 2009 Rick: The lamps should only be lit when there is a short or overload. In DC operation the resistance of a motor is high enough that it provides most of the load and the lamp doesn't light. A direct short makes the lamp take all the load. A number of locos (Hornby Dublo ones especially) can cause the lamp to glow and even shine, impeding train running. I don't have DCC handy to experiment with. and The lamps are current limiters. ... There is lots of debate about whether the bulb approach is "sensible" - one important point is to ensure that the bulbs are adequately ventilated; they will run quite hot when illuminated. David and Cliff : Thanks for both your very valuable replies. I now fully understand the role of the car lamps as current sinks. And i think that it's a good idea; other than that it doesn't seem likely to trip off the command station. I can imagine that mounting such a bulb under the layout would be readily seeable when a short occurs. A great way of bringing your immediate attention to a problem. Thanks again guys for the info. best regards, Link to post Share on other sites More sharing options...
Road Stone Posted November 1, 2009 Author Share Posted November 1, 2009 There is more to this than meets the eye and I only wish I could experiment, which I can't at the moment. What is the likelyhood of damaging a decoder? Has anybody experienced the problem described? Cheers, Jerry Link to post Share on other sites More sharing options...
Guest Moria Posted November 1, 2009 Share Posted November 1, 2009 Another solution is to use circuit breakers such as the DCC specialities Powershield series between the Booster and the track sections. I have one booster and 7 Powershields feeding parts of the layout. In this way any short only affects part of the layout, the rest keeps running fine, and the powershields can be adjusted for the level at which they trip. As it happens, they also do an autoreverse unit, which is completely solid state, therefore much faster, no loud clicks and no sparks when triggerred. and can control points through either a tortoise or a snap action point motor automatically. Note :- I have no connection with DCC Specialities other than as a very happy customer. Edit :- As to your other question, I have had many shorts on this set-up, both accidental and intentional and with upwards of 30 locos on the layout and upto 10 moving at once (I use computer control) I have never had a short affect or damage a decoder, unless the short was because of a decoder short in the loco itself. I use a Lenz 100 system with Lenz silver mini decoders. However, as in all cases, your mileage may vary Regards Graham Link to post Share on other sites More sharing options...
Road Stone Posted November 1, 2009 Author Share Posted November 1, 2009 Another solution is to use circuit breakers such as the DCC specialities Powershield series between the Booster and the track sections. I have one booster and 7 Powershields feeding parts of the layout. In this way any short only affects part of the layout, the rest keeps running fine, and the powershields can be adjusted for the level at which they trip. As it happens, they also do an autoreverse unit, which is completely solid state, therefore much faster, no loud clicks and no sparks when triggerred. and can control points through either a tortoise or a snap action point motor automatically. Note :- I have no connection with DCC Specialities other than as a very happy customer. Edit :- As to your other question, I have had many shorts on this set-up, both accidental and intentional and with upwards of 30 locos on the layout and upto 10 moving at once (I use computer control) I have never had a short affect or damage a decoder, unless the short was because of a decoder short in the loco itself. I use a Lenz 100 system with Lenz silver mini decoders. However, as in all cases, your mileage may vary Regards Graham Thanks for answering my question. Just peace of mind required!! Cheers, Jerry Link to post Share on other sites More sharing options...
craigwelsh Posted November 2, 2009 Share Posted November 2, 2009 Re the bulb stuff, only a couple of expensive solid state circuit breakers can trip faster than the Dynamis command unit so the bulb method is a cheap way of guaranteeing that cocking up in the fiddle yard when railing something won't immediately stop everything in the scenic zone for example. Its intended for these short um shorts that you will sort out quickly and apart from ventilating the bulb its fine. Your wiring should always cater for the maximum output anyway with nice big bus wires.. Land rover tail bulb was trialled with Dynamis, 12V 5W, drop a screw driver on the track and command station doesn't trip. Loco was fine during this as well. Remove screwdriver and all back to normal. Dutch_master - not sure what you mean, why would you leave a short to go on and on when normally you note something went wrong, especially with a nice bright bulb to remind you! Take the bulb out and the whole layout would still trip. Hornby and Bachmann decoders sometimes lose their address if the loco shorts itself (ie run into opposite set point, bulbs can help here if you use DCC point control!). Its never happened to me with a Lenz chip though. Link to post Share on other sites More sharing options...
Parkerlaw Posted January 30, 2010 Share Posted January 30, 2010 Dynamis and Auto reverse modules The relay operated ones dont work. Dynamis trips quicker than the relay changes Did ask Bachmann for a solution or a module which would work with their system. This was at least six months ago and still no response eveen after resubmitting question several times I did'nt fancy using the bulb method or using switches. I spent ??45 on a good solid state electronic relay. Works really good Link to post Share on other sites More sharing options...
Suzie Posted January 31, 2010 Share Posted January 31, 2010 Dutch master's diagram above shows that you do not need to use a dead frog. Close examination of the diagram shows that the blue wire going to the reverse loop and the brown wire going to the frog are at the same polarity, so the frog can be connected to the blue wire and does not need a switch even when using a sprung trailing point when the frog will be powered by the autoreverse module. Link to post Share on other sites More sharing options...
RMweb Gold Donw Posted January 31, 2010 RMweb Gold Share Posted January 31, 2010 Alsoof interest in Frebruary Model Railroader short review of the Tam Valley Depot Hex frog Juicer. DonW Link to post Share on other sites More sharing options...
adriancr Posted February 16, 2011 Share Posted February 16, 2011 Hi All. I've been scouring the web and forums to find a cost effective Auto Reverse Module that works with the Bachmann Dynamis. From an advert in the Model Railroad Hobbyist on-line magazine I got to looking at the products from Tam Valley Depot. With the helpful assistance of Duncan Mcree at Tam Valley Depot and after installing Tam Valley Depot's DCC Dual Frog Juicer/Auto-Reverser/Circuit Breaker for the turntable on my layout, I can confirm that Tam Valley Depot's DCC Dual Frog Juicer/Auto-Reverser/Circuit Breaker (scroll about 2/3 down on the page) works great as an Auto Reverse Module with the Bachmann Dynamis and it is at a very competitive price. Regards, Adrian Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted February 16, 2011 RMweb Premium Share Posted February 16, 2011 Dynamis and Auto reverse modules The relay operated ones dont work. Dynamis trips quicker than the relay changes How about LDT KSM-SG module? Doesn't rely on a short circuit at all. It has two sensor tracks, one each end long enough for a loco and the main isolated section of track. Senses which polarity is required and changes without a short circuit. Keith Link to post Share on other sites More sharing options...
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