DCC Track Wiring

[Dave4468]

These are probably the simplest questions related to DCC anywhere but I am having a time finding an answer to them! 

 

The first one is how to wire up the feeds. The layout in question is a fairly simple depot, track plan as below;

My basic understanding is that every siding needs a feed as does the middle pair of points of the run of four in the top left, the curved points in the middle, the two short bits of track towards the middle and everything attached to the turntable, so basically everything!   Firstly is that correct or do I need more/less? 

 

Next thing, I plan to use a Gaugemaster Prodigy Express to control this. To do this do I simply connect a common feed and common return (DDC Bus?) to the controller and then have individual droppers connected to each feed as needed? Is that correct? If so what sort of cable do I need? I assume the standard cable available from GM/Peco etc is suitable but what about the Bus?

 

And finally. There seems to be several answers to "will electrofrog points work with DCC out of the box?". Obviously the three way points already have accessory switches and frog polarity switching as its needed anyway so they are covered. What about the normal ones? Some say they work fine as long as IRJs are used on the vee rail. Others seem to say you need to snip the little wires bridging the gap on the frogs, fit an accessory switch and switch frog polarity that way. Which is correct/best?

 

Cheers for any help! 

[mikeg]

You also need to use isulated joiners on all frog rails to stop feedback shorts, otherwise it is two bus wires of quire large size, an droppers from each section of track, DO NOT rely on rail joiners, I have had to put in about 10 feeds due to faulty joiners in 7/8 years.

 

regards

 

mike g

[Brian]

Hi Dave,

You are on the right track (No pun).

But the Peco three way point doesn't have any built in switching other than its rails moving. If you obtain the Elecrofrog three way you will have to add some sort of change-over point operated switching for the frogs polarity. Often via a switch on the point motor - Peco PL10 with PL13 or PL15 switch, Seep PM1 or use Tortoise or Cobalt etc slow motion stall motor with built in change over switches.

 

In addition you will need to fit two Insulated Rail Joiners (IRJs) to each Electrofrog points Vee rail ends and four IRJs are needed on the three way Electrofrog.

 

As for the DCC bus pair you can use 32/0.2mm equipment wire or solid core wire often stripped from former mains cable the outer sheath being removed - 1.5mm² being about the smallest size for a DCC bus pair.

Droppers to the track are normally 16/0.2mm equipment wire, but if the actual dropper to the bus is kept short to around a max. of 300mm and you instal droppers to each section of track and on the points too then 7/0.2mm equipment wire can be used.

 

You may find having a read through my DCC  page of some help? http://www.brian-lambert.co.uk/DCC.htm

 

 

Edit to correct spelling.

[Dave4468]

You also need to use isulated joiners on all frog rails to stop feedback shorts, otherwise it is two bus wires of quire large size, an droppers from each section of track, DO NOT rely on rail joiners, I have had to put in about 10 feeds due to faulty joiners in 7/8 years.

 

regards

 

mike g

 

What, so basically every single section of track will need its own feed?

[Dave4468]

Hi Dave,

You are on the right track (No pun).

But the Peco three way point doesn't have any built in switching other than its rails moving. If you obtain the Elecrofrog three way you will have to add some sort of change-over point operated switching )Often via a switch on a point motor - Peco Pl10 with PL13 or PL15, Seep PM1 or use Tortoise or Cobalt etc slow motion stall motor with built in change over switches.

 

In addition you will need to fit two Insulated Rail (IRJs) Joiners to each Electrofrog point and four IRJs are needed on the three way Electrofrog.

 

As for the DCC bus pair you can use 32/0.2mm equipment wire or solid core wire often stripped from the outer sheath of mains cable - 1.5mm2 being about the smallest size for a DCC bus pair.

Droppers to the track are normally 16/0.2mm equipment wire but if the actual dropper to bus is kept short to around a max of 300mm and you instal droppers to each section of track and on the points too then 7/0.2mm equipment wire can be used.

 

You may find having a read through my DCC  page of some help? http://www.brian-lambert.co.uk/DCC.htm

 

I've already wired up the three way and paired it with PL-13s to do the switching as per its instructions. Each point already has the IRJs fitted. A quick read of your website would suggest that while the conversion of the points is not needed it will be worth it? I assume given that a depot is all very slow running it will be worth the effort?

 

Thanks for the bus answer. Somewhere I else I have seen these recommended as a good bus wire; http://www.maplin.co.uk/twin-power-cable-20666, I assume with those as each cable is independent of the other that can be both feed and return? 

[smokebox]

In an ideal world, every piece of track, including points, will have a pair of power feeds to ensure there is no reliance on rail joiners for electrical power.  It's not unknown for exhibition layouts to have two feeds "just in case"

[Crosland]

Thanks for the bus answer. Somewhere I else I have seen these recommended as a good bus wire; http://www.maplin.co.uk/twin-power-cable-20666, I assume with those as each cable is independent of the other that can be both feed and return? 

Being figure 8 is good as it hold the conductors in close proximity, minimizing stray inductance, but makes attaching droppers more fiddly. Maplin also do figure 8 speaker cable which is 42/0.2 (XR60Q), equivalent to the 15A cable you linked to, at a lower price. Even cheaper on a reel (N20AP).

 

I use individual conductors, as I find it makes stripping back a short length of insulation easier for connecting droppers.

 

Andrew

[Vonzack]

Hi Dave4468,

 

Nice track plan BTW.

 

I'd like to echo smokebox's comments, you really should aim to put track feeds on each piece of rail and each point. I typically have droppers every 30cm of track and try not to rely on just one set of droppers per rail.

 

You should aim to use wire which is rated in excess of your Command Stations output. As this will typically be 5A, then something 6A or over will be OK for bus wires. I tend to also fit dropper wires which are capable of conducting 3A, so there should be no way demand from the rails (in N) should exceed the droppers rating. I tend to use single conductor and twist the cables to keep them tidy under the board.

 

Consider modifying your points by isolating the frog and feeding the blades from the stock rails, this can eliminate micro shorts (which are caused by the point blades coming into contact with the opposing stock rails before the polarity has switched, these if long enough will shut down your command station as it may think its detected a permanent short). I haven't seen many of the Peco 3-way points, but looking at pics on the web, they appear to be manufactured with isolated frogs. A top tip is to use a jewellers saw to isolate the frog, they can be found cheaply on eBay and make a very fine cut.

 

Remember you will need an Auto Reverser attached to your turntable feeds.

 

Cheers, Mark.

[Crosland]

Remember you will need an Auto Reverser attached to your turntable feeds.

That rather depends on the turntable and the OPs locos.

 

A turntable with a commutator ring will switch the polarity for you, but may cause interruption with sound decoders when it switches. A reverser could be beneficial in the latter case.

 

Andrew

[Dave4468]

That rather depends on the turntable and the OPs locos.

 

A turntable with a commutator ring will switch the polarity for you, but may cause interruption with sound decoders when it switches. A reverser could be beneficial in the latter case.

 

Andrew

 

The turntable I am planning to use is the standard Peco LK-55 kit. Does that chance anything?

[Dave4468]

Is it possible to test DCC wiring using a DC controller or does it need to be done with a DCC controller? 

 

Question arises because I have wired my first few bits a track to the bus, attached the bus to an old H&M 2000 controller and boom, nothing. 

[mcowgill]

It should work fine with a DC controller.  

 

Regardless of whether it is DC or DCC, you are still wiring up a 2-rail model railway, the only difference is that you have no section switches to turn off sidings and you are not using the any form of 'self isolating' with points that automatically stop feeding a siding when you switch them to another route.

[mcowgill]

Do you have a multimeter or something similar you can use to check continuity?

 

I'm not sure I would know where to start without my meter, it can quickly tell you whether you have a short, probably from accidentally bonding one of the rails/droppers to the wrong side of the bus.  

[Dave4468]

Now you've said that I realised I had an embarrassingly obvious sort circuit! I've stripped insulation from the bus at lengths along it for future droppers to be fitted but I'd not separated the wires so there were simply touching! 

 

Now they work!

[mcowgill]

It's nearly always something simple, glad to hear you're moving in the right direction!

 

Martin

[Dave4468]

When I'm wiring the points for frog switching is it possible to use the bus to provide the current to switch the polarity of the frogs rather than having to solder to the rails. Surely if I connect the accessory switch inputs that would normally be soldered to the rail to the correct dropper wire it will have the same effect without needed to do more soldering to the rail. (I am trying to keep soldering to rails to a minimum, so droppers only where possible, I'm ok at it but not very neat!) 

[Crosland]

When I'm wiring the points for frog switching is it possible to use the bus to provide the current to switch the polarity of the frogs rather than having to solder to the rails. Surely if I connect the accessory switch inputs that would normally be soldered to the rail to the correct dropper wire it will have the same effect without needed to do more soldering to the rail. (I am trying to keep soldering to rails to a minimum, so droppers only where possible, I'm ok at it but not very neat!) 

That's fine, so long as you get them the correct way round :-)

 

Andrew

[Dave4468]

I assume if I've got them the wrong way round while I'm testing with DC the loco will just stall? 

[Crosland]

I assume if I've got them the wrong way round while I'm testing with DC the loco will just stall? 

It will cause a short when a wheel bridges the gap between a rail and the mis-wired frog.

 

Andrew

[Dave4468]

Coming across more point based bizarreness.

 

I've wired up a 3 way point (SL-E99) as per the in pack instructions which appear to be the same as those on http://www.brian-lambert.co.uk. Now when I test it the loco will happily go down the middle line and the right line from the point but stalls on the point when going down the left line. So the frog switching is clearly working for two of the lines but not the third.

 

Any reason spring to mind? 

[Dave4468]

Is the isolation gap 100% necessary in electrofrog points? I've bought an SL-E98 Y Point which doesn't have the factory fitted gap annoyingly and I don't have the tools to start attacking the rail. Can I hope it'll be fine or does it desperately need it? 

[Vonzack]

An isolation gap is not necessary if your polarity switching is perfect, but if the polarity of the frog switches too early or too late, then you can cause micro-shorts that will disrupt your command station. Re-read post #9. With OO / HO, the tolerances are much larger than they are in smaller scales, so you may get away with it.

 

Also, use a hand tool to make the cut, a dremel or other power tool if not used sparingly, will generate allot of heat and probably melt the sleepers near the cut.

 

Cheers, Mark.