Converting a Layout to DCC - Guidance Appreciated

[NinthPlanet]

Hello all. I am planning to convert my 6' x 4' layout to DCC control (via an eLink unit). I have used AnyRail to come up with a rough DCC wiring diagram and would appreciate any comments on it. I'm particularly interested in knowing if I need to add any power boosters, additional link wires or insulate any parts of the layout. I only intend to run two locos on the layout at the same time and a total of six will be placed on the layout.

I understand that I need to fit power clips to the points, and that to use the Hornby R070 turntable I need to remove the brass contacts from the rotating section and use a loco decoder to command the turntable. The points are switched by hand.

The layout diagram is split into two parts: the external running loop detail and the internal running loop detail (because I used a trial version of AnyRail, it limited me to 50 pieces of track):

http://i.imgur.com/rd8rypL.jpghttp://i.imgur.com/qu0zmtm.jpg

[Chrissaf]

interested in knowing if I need to add any power boosters,

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No absolutely not

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When you had the layout as DC. Did you have insulated joiners between the crossover points facing each other between the two ovals at the 5 pm position. If you did, these will ideally need to be replaced by metal ones for DCC. Or alternatively just leave the R8201 link wire in place at the 8 pm position. Replacing the insulated joiners with metal ones may be more reliable electrically.

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You have no 'Reverse Loops', so that is one hurdle you won't have to jump over.

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The DC track power connectors (R602 or R8206) will need either replacing or modifying to DCC ones. DCC replacements are R8241 or R8242. The DC to DCC modification of the existing ones to DCC involve opening the cover of the power clip and cutting out the small disc capacitor you will find under the cover.

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The TT is your only 'sticky wicket' there is a topic thread running live at this very moment in time, that I would recommend you have a look at and ask further questions there if necessary. The later posts in the thread are more relevant to your question.

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The post can be found here

[NinthPlanet]

interested in knowing if I need to add any power boosters,

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No absolutely not

That's good to know, thanks.

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When you had the layout as DC. Did you have insulated joiners between the crossover points facing each other between the two ovals at the 5 pm position. If you did, these will ideally need to be replaced by metal ones for DCC. Or alternatively just leave the R8201 link wire in place at the 8 pm position. Replacing the insulated joiners with metal ones may be more reliable electrically.

The joiners (fishplates?) between the 5pm points are metal. I don't use any isolated rail joiners on the layout (it lets me be really lazy and avoid having to switch direction on the HM2000 controller when moving trains between the two ovals!).

The layout pictures in my earlier post show the layout as intended, not as it is currently. I don't currently use a wire link on the layout, but two DC power clips (one to each oval) connected to an HM2000 controller.

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The DC track power connectors (R602 or R8206) will need either replacing or modifying to DCC ones. DCC replacements are R8241 or R8242. The DC to DCC modification of the existing ones to DCC involve opening the cover of the power clip and cutting out the small disc capacitor you will find under the cover.

Thanks. I'm going to connect the eLink to the layout via an R8241 power track and buy R8242 power connectors for anything else.

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The TT is your only 'sticky wicket' there is a topic thread running live at this very moment in time, that I would recommend you have a look at and ask further questions there if necessary. The later posts in the thread are more relevant to your question.

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The post can be found here

Thanks. I'll have a read of it. You've been very helpful.

[96RAF]

Aimed at the sticky wicket TT case  - and based on experience and lack of space to fix it- try to get a straight run onto your TT, never approach on a curve, else a derail is likely

[RDS]

@NinthPlanet

Is the extra length on each TT output so that you can store multiple Loco's, otherwise I would have thought that the maximum length would be just a bit more than the length of the track on the TT.

[NinthPlanet]

Aimed at the sticky wicket TT case  - and based on experience and lack of space to fix it- try to get a straight run onto your TT, never approach on a curve, else a derail is likely

The run onto the turntable does work OK without derailing (occasionally it happens - usually with my apple green Tornado), but I agree with your advice - hence why the other ramps up to the turntable are all straight. There is a Peco ST-202 79mm straight before the Hornby on-ramp straight, so enough of the loco is straight before entering the turntable. I've found that ensuring that the path up to the turntable is as gentle a gradient as possible also helps to reduce the likelihood of de-railing.

[NinthPlanet]

@NinthPlanet

Is the extra length on each TT output so that you can store multiple Loco's, otherwise I would have thought that the maximum length would be just a bit more than the length of the track on the TT.

Yes, the three straight turntable outputs are used for storing locos. I like to keep my locos in Peco loco lifts to avoid damaging them - especially Tintagel Castle which has that [many expletives] four thin wire connection between loco and tender. What I like to do is roll the loco out of the lift and then reverse it back to the buffer. That's why I aim for an R600+R601 in length - so the loco can safely exit the loco lift with enough straight track before the turntable to prevent a de-railing.

[Dazzler down under]

Hey guys, hope you dont mind me chiming in, but seen as there is a diagram ive gotta ask, in the first diagram there is only 1 ramp onto the tt, on a dcc layout would it be possible to just leave the tt dc and control it independent with a dc controler seen as it will be used for only turning locos?

[Chrissaf]

You can certainly keep the TT turning under DC using a DC layout controller dedicated just for the TT to turn it. The bridge track still needs isolating for DCC use though. Even if there is only one lead in track (with no output tracks) as soon as the TT starts to turn (DCC track is live all the time remember) the moving rail will short on the fixed rail as it turns - see drawing.

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/media/tinymce_upload/e1799f16970dd6f3684e11b352bee28b.jpg

[Dazzler down under]

But both rails are dead once the TT turns so how can there be a short?the only time the tt rails are live is when the bridge is aligned with inlet ramp, once the bridge turns the tt rails are dead. Im gonna hook up my tt tonight and find out.

[Fishmanoz]

DCC runs at full volts all the time, even when all locos are stopped.  So as soon as you make a contact to the bridge, it is always there and will short out as per Chris's diagram when it rotates.

[Dazzler down under]

Just hooked up my tt, drove loco onto tt, turnt loco no probs with no short, unless the bridge is aligned  to the outlet there is no power to the bridge so as soon as it moves its dead, ive done a dozen rotations with no probs whatsoever, then drove loco off the tt.

[Dazzler down under]

Also on diagram 1 where he has the link wire  from the outside oval to the inside oval i dont think its required as the point clips at the crossover should ensure power to both loops?

[Chrissaf]

Assuming the standard unmodified Hornby R070 TT. This turntable has wires underneath the TT from the input track to the bridge rails. On a DC layout, the power is off thus the input track and the bridge rails are dead. But on a DCC layout, these rails will be live all the time. The bridge rails are electrically connected to input rails, so that the bridge rails can transfer power to any outlet tracks that might be attached when the loco is required to drive off the bridge and into a previously dead siding.

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This is how it is supposed to be, using an unmodified Hornby DC TT and unmodified track approaches to it on a DCC layout. If your TT bridge is dead as it turns. Then it has either been modified in some way, or the wire links under the TT are faulty in some way.

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We are assuming of course that your TT is a Hornby R070 one. If not, then it is likely that your particular TT model does not have the bridge link wires as part of its design.

[NinthPlanet]

Also on diagram 1 where he has the link wire  from the outside oval to the inside oval i dont think its required as the point clips at the crossover should ensure power to both loops?

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Hi. From what I understand the link wire is a good idea because it allows a lower resistance, higher current connection between the outer oval (where the DCC control signals enter the layout) and the inner oval. The point clips are just thin bits of metal, so will have a higher resistance and a lower current rating than a piece of cable. This may not be a problem for my layout, but larger layouts with more running locos will draw a greater current through the point clips and may cause the point clips to heat up. The manual for the Hornby Select DCC controller advises a link wire between two ovals rather than relying on the point clips.

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What I'm not sure of is whether I should use insulating fishplates between the two points at the crossover between the loops in order to avoid two copies of the control signals flowing around the inner loop.

[NinthPlanet]

Just hooked up my tt, drove loco onto tt, turnt loco no probs with no short, unless the bridge is aligned  to the outlet there is no power to the bridge so as soon as it moves its dead, ive done a dozen rotations with no probs whatsoever, then drove loco off the tt.

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How is your turntable's motor connected to the layout? Is it via a yellow lever (R046 - Two-way lever switch 'on-on')? If so, power is only provided to the turntable motor or the track - not both at the same time. This setup won't work under DCC because a) DCC won't provide the DC voltage required for the turntable's motor via the lever and b) the DCC control signal will reach the turntable's bridge anyway.

[Chrissaf]

What I'm not sure of is whether I should use insulating fishplates between the two points at the crossover between the loops in order to avoid two copies of the control signals flowing around the inner loop.

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No you won't need isolation between your two ovals. The digital signal propagates very fast. It is not the speed of light as most people think, but could be considered so for the size of your layout. You would need to have 100s if not 1,000s of metres of track before digital signal phase distortion** became an issue.

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** distortion caused by two copies of a signal arriving at a destination point via two different paths at different times.

[Rog RJ]

Now if it was me, i'd say fitting insulated fishplates between the two ovals is a good idea for a number of reasons.

 

Firstly it can help with some locos that can cause a short circuit to occur when passing through.  It shouldn't happen but sometimes does. I have a flying Scotsman that does it for some reason.  It doesn't create a short circuit anywhere else except one of my crossovers and insulated fishplates prevent it from happening.

 

Secondly, if you ever need to fit a booster (which you probably never will) you have a track break already fitted which can be used to break the layout into two power districts, the inner loop and the outer loop.

 

Thirdly, can be very handy for fault location purposes, allowing a fault to be quickly localised to the inner or outer tracks.

 

[Dazzler down under]

Sorry guys I didn't explain myself very well, I'm not using the inlet with the brass contacts at all, there is no power going to that ramp at any stage of the rotation, I'm using a non powered inlet ramp so the only way power gets to the bridge is when it's aligned with the track as soon as the brass contacts disengage the track the bridge is dead for the whole rotation ill post up a video later if I can figure out how and put it on my own thread, sorry for hijacking this one 

[Dazzler down under]

Sorry guys I didn't explain myself very well, I'm not using the inlet with the brass contacts at all, there is no power going to that ramp at any stage of the rotation, I'm using a non powered inlet ramp so the only way power gets to the bridge is when it's aligned with the track as soon as the brass contacts disengage the track the bridge is dead for the whole rotation ill post up a video later if I can figure out how and put it on my own thread, sorry for hijacking this one 

[Dazzler down under]

Sorry guys I didn't explain myself very well, I'm not using the inlet with the brass contacts at all, there is no power going to that ramp at any stage of the rotation, I'm using a non powered inlet ramp so the only way power gets to the bridge is when it's aligned with the track as soon as the brass contacts disengage the track the bridge is dead for the whole rotation ill post up a video later if I can figure out how and put it on my own thread, sorry for hijacking this one 

[Fishmanoz]

Dazzler, you can avoid multiple posts by not hitting reply multiple times.  Even if your browser progress bar appears to lock up, your reply will be posted.  Navigate back to the original site and you'll see your post showing as the latest one made.

 

Your method does work as you've found except there are 2 provisos.  The first you know, you can't use the inlet track.  The second is you can't use out,ets at 180 degrees to each other either or you are back to the short condition in Chris's diagram as soon as it starts to rotate.  And of course you have to power every inlet/outlet. And down the track if you get sound locos, they'll lose sound as soon as the bridge rotate, get it back in blips as you pass each powered outlet, and not get it back until the TT stops at the final position you turn it to.

 

It it doesn't matter which method you use with this TT, there will be upsides and downsides because of its DC design.  If you can understand what they are, you can decide which method is best for your situation.  That includes using john's solution - buy one designed for DCC and not have these problems in the first place.

[NinthPlanet]

Now if it was me, i'd say fitting insulated fishplates between the two ovals is a good idea for a number of reasons.

 

Firstly it can help with some locos that can cause a short circuit to occur when passing through.  It shouldn't happen but sometimes does. I have a flying Scotsman that does it for some reason.  It doesn't create a short circuit anywhere else except one of my crossovers and insulated fishplates prevent it from happening.

 

Secondly, if you ever need to fit a booster (which you probably never will) you have a track break already fitted which can be used to break the layout into two power districts, the inner loop and the outer loop.

 

Thirdly, can be very handy for fault location purposes, allowing a fault to be quickly localised to the inner or outer tracks.

 

Food for thought. Thanks. :)

[Dazzler down under]

O dear, sorry about the multiple posts guys, thats exactly what happened Fishman the progress bar locked up for an extended period and i hit it a few times out of frustration thinking it wouldnt post but it did and i was on my break at work . Lesson learnt.

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If you have a look at the 2009 plan9 on railmaster thats exactly how my yard is set up, there are no other ramps off the turntable, only the 2 inlets so all i wanna do is turn the loco. I will loose sound upon rotation but i can live with that because the TT motor is loud as and  if i have other sound locos running on the layout  the loco on the TT will be drowned out anyway.

thanks for the help guys and i promise you wont have to read this post 27 times lol.

[NinthPlanet]

By way of update, I have completed phase one of the layout conversion. I fitted insulating fishplates between the inner and outer ovals as Rog (RJ) suggested. Everything is working well at the moment. 😀

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The turntable has been disconnected from the layout until I decide what wiring approach I should take. I fitted the basic Hornby DCC loco decoder to my Rebuilt Baby Scot (which helpfully had a little slot for the decoder) and R.E.M.E is working well. Ketley Hall has spent the first running hour coating the tracks (and the wheels of her Pullman coaches) with oil! I didn't apply any oil myself - it's the stuff the factory applied.