DCC Beginner Questions

[NSE456]

Hello,

I've always used DC but have since taken an interest in DCC and I am aiming to wire up a new 8x6ft layout to DCC. I have recently got hold of a nice pre-owned Hornby Select controller which is V2.0 and have watched all sorts of guides but since people seem to approach it differently (and I'm aware that will be the case here also) I'd just like to talk through some of my conclusions and plans and gather some opinions.

Wiring

Advice here seems to vary from just one connection will do, all the way up to having every bit of track connected with bus wires and isolated sections, circuit breakers etc.

I'm aware using the Select on an 8x6ft layout makes it quite a small and low powered system, but so I have room to potentially replace my controller at a later date. I was thinking of maybe putting in bus wires for the 2 loops with 3 or 4 dropper wires spread evenly around each loop, then wiring up all the sidings so they are live. Any thoughts on this approach?

Frogs

I have many Hornby and Peco points with insulated frogs and would like to keep these, from what I've gathered the main issue people have on these with DCC is locos stalling on the frog? Since most of my locos have multiple pickups and long wheelbase I do not think this will be an issue. I also plan to make my sidings always live using dropper wires from the bus. Can I just install the points as normal with regular fishplates?

How many Locos

I'm struggling to understand the details on this but my understanding with the Hornby Select is it may run up to 9 locos with the 4amp adapter but can program up to 59 locos, what does this mean exactly? Can I have 59 locos sitting on a shelf all programmed by the controller, and put any 9 of them on the layout at once and they will go?

Can I just swap them out whenever I fancy it without needing to reprogram?

Can I have more than 9 on the track but only be able to move 9 at once?

Dual Decoders

I was consdering buying a new HST but having seen the prices I've decided I'm actually quite happy with my old one. Either way I will be upgrading the lights and installing a decoder in either end so the lights can work. I understand other models such as the Javelin also need a Decoder in either end for lights etc.

My question is once I combine these on the controller, will they count as 2 out of my 9 locomotives I can run all at once or will they count as 1?

Is this futureproof?

Finally (and thank you if you got this far) I would like to ask if this is a good route to allow potential upgradability. I'm coming in at the entry level of DCC and while I'm only really interested in the lights and improved control features (things like sound, automation etc do not appeal to me) I may want to keep my options open for a more advanced controller in the future. Is there anything else I can do thats still cost effective today, but may make such an upgrade easier in future?

Thank you.

[P-Henny]

I was thinking of maybe putting in bus wires for the 2 loops with 3 or 4 dropper wires spread evenly around each loop, then wiring up all the sidings so they are live. Any thoughts on this approach?

 

 

A perfect solution for your planned size of layout. Noting that if your layout and/or track has been (or has been taken from) a previously existing Analogue DC layout. Then make sure all Analogue DC power tracks and/or track power connectors are either replaced with digital versions or modified for digital use by opening them up and removing the Analogue supression capacitors.

 

 

I also plan to make my sidings always live using dropper wires from the bus. Can I just install the points as normal with regular fishplates?

 

 

Yes

 

 

my understanding with the Hornby Select is it may run up to 9 locos with the 4amp adapter but can program up to 59 locos, what does this mean exactly? Can I have 59 locos sitting on a shelf all programmed by the controller, and put any 9 of them on the layout at once and they will go?

 

 

The Select has only 59 DCC Addresses (1 to 59) in its DCC Address pool that can be allocated to a DCC Locomotive decoder. It can only control one address at a time. But this does not stop you from having more than one loco running at a time. The number of concurrently controlled locos only being limited by the amount of current from the power supply to power them. So yes, you could have potentially up to 10 running concurrently on the layout if using the 4 Amp power supply, or maybe more if the locomotive electric motors in question draw very low currents.

Let me explain something that you haven't actually asked about i.e using a DCC Controller to control multiple locos.

Purely as an example for descriptive purposes. Let's say you have three locos on the layout that have been configured with three DCC Addresses. Addresses 10, 15 & 18. These three locomotives are placed one on loop 1, one on loop 2 and the third loco in the sidings.

The loop 1 loco with DCC Address 10 is selected by the Select and set going round loop 1.

The Select can now select the loco on loop 2 with DCC Address 15 and set that running round loop 2. The loco on loop 1 (Address 10) continues to run round loop 1 with the last command it received even though the Select is no longer in direct communication with it (as a different DCC Address to control has now been selected).

The Select can now select loco 3 with DCC Address 18 and control that to perform shunting duties in the sidings whilst the other two locos continue to trundle round the loops until selected again and told to do something completely different.

As an analogy, think of the Select controller (indeed any DCC controller) as being a virtual locomotive driver, and this driver is able to jump in and out of different locomotive cabs at will.

If you expand this concept, then this virtual driver (the Select controller) can jump at will in and out of any of the potential 59 locomotives and issue commands. The only limiting factors are:

1. Having enough current from the power supply to operate multiple locomotives.
2. The mental and physical dexterity of you to use the Select controller to remember what you are doing and keeping track of the locomotive control actions taken and activities invoked.
3. It is the 4 Amp power supply that limits you to running up to 10 locos concurrently. It is not an addressing limitation as described above.

 

 

Can I just swap them out whenever I fancy it without needing to reprogram?

 

 

Yes ... as long as all locomotives have DCC Addresses in the 1 to 59 range.

 

 

Can I have more than 9 on the track but only be able to move 9 at once?

 

 

You could have all 59 on the track, and control as many as you have the power supply current capacity to operate concurrently within your mental capacity & dexterity as mentioned previously.

 

 

My question is once I combine these on the controller, will they count as 2 out of my 9 locomotives I can run all at once or will they count as 1?

 

 

It depends. If the front power car decoder and the rear dummy car decoders are given the SAME DCC Address. Then only one DCC Address of the 59 Address pool is used to control both decoders. If the two decoders are given different DCC Addresses, then this uses up 2 addresses of the 59 DCC Address pool. In a HST scenario, it is typically normal practice to give both decoders the same DCC Address.

 

 

Is there anything else I can do thats still cost effective today, but may make such an upgrade easier in future?

 

 

For the physical size of layout you are proposing, I doubt that you will want to run concurrently more locos than the 4 Amp power supply can support. So I don't think you need to consider introducing 'power domains' which is a more advanced DCC power distribution concept.

Yes a more capable controller will provide more functionality than the Select, but such an upgrade is unlikely IMO to warrant or need any corresponding changes to the layout wiring etc to support a different controller. A different controller isn't going to inherantly give you the ability to run more locos concurrently. The concurrent loco limitation is a function of the power supply current, not the controller. A different controller can however give you the ability to configure more than 59 locomotive addresses. The Hornby Elite for example supports the DCC Address range 1 to 9999.

So far, you haven't mentioned controlling points and signals using DCC. The Select is also DCC Address range limited for Accessories too (61 to 99). Whereas the Elite Accessory range is 1 to 2048.

IMPORTANT: My reply is very long. Please do not use a 'Quoted Reply'. Just use the main reply text box at the bottom of the page.

[NSE456]

Hello and thank you for taking the time to respond.

I will be using my old DC track but since I used PECO powered fishplates on that I plan to either reuse these or to solder the dropper wires directly onto the underside of the rails. I will probably do a mixture of both as it seems to be the most cost effective option for me. I was going to do some testing with a DC Power track though so good to know to avoid those on DCC.

The virtual driver example is perfect as thats actually very similar to how I plan to run my layout. I will probably include a few trains on standby in sidings as I like the lights, but since I can set those up and leave the lights running when I jump to other locos that works for me.

The only thing I think I'm missing out on is the ability to name locos by class number if they are a number above 59, but thats fine I can write out a list.

It makes sense combining the decoders onto the same number for the HST, although I'm wondering how I can program it to know which end is which? If they are both the same would they both display headlights at the same time for example?

Truth be told its that side and the CVs and programming thats always scared me with DCC. Since I'm getting only a small amount of decoders at a time and upgrading my locos gradually I might well save that one for when I'm more confident with the basics, or maybe it will be a good learning experiance to get stuck into now.

[ColinB]

For the HST, DCC is direction dependant so if you think about one HST is facing forwards the other is facing backwards so when you tell the HST to go forward the white lights will come on the forward facing HST and the rearward facing HST will have red lights as it is going backwards. What I do is buy a decent decoder for HST with the motor in and buy a cheap decoder like a LaisDCC for the rear one as it is only controlling lights. You could use a function decoder but a normal decoder is cheaper. I very rarely program CVs unless I have to, but you will have to set the address in each loco. My layout was DC with lots of separate sections. I kept the separate sections although they are all powered by the same DCC feed, it makes it easier to find a short if you get one. For your insulated frogs the only issue will be those locos with a small wheelbase, same issue as DC, but with DCC you can add "stay alive" circuits which means the loco will behave like it is running on a battery for the sections of the track where it loses power.

[P-Henny]

With regard the rear dummy motor car of the HST. You say it will be an old one with a lighting kit fitted. This suggests it will not be 'DCC Ready' with a socket but custom wired either with a socket added DIY or just hard wired.

As Colin says, when the rear car decoder is commanded to go forward, you would want the red LEDs on it to light up not the white LEDs.

You can either adjust CV29 to set the 'reverse' bit OR just wire the white and red LEDs in reverse, so that the Red LEDs come on when the White LED wire is switched on, and vice-versa for the White LED. Some commercial HST lighting kit instructions include wire reversal instructions in the kit to save having to edit CV29. Noting that the front motor car would have the lights wired straight as per standard specification.

Noting also that some (not all) decoders need a motor attached before a DCC Address can be configured in the decoder. A common way to do this, is either to program the decoder with its DCC Address in a decoder tester or in another loco before installing it in the rear dummy motor car.

[NSE456]

It is an older HST which I guess had the ringfield motor at some point but has had an attempt at being converted into a CD Motor. I brought it on the cheap as a bit of a project for me to restore, so I'm going to fit new lights and solder on a DCC socket. Given that I probably wouldn't be comfortable selling it on with all those changes I'll probably try wiring the dummy cars LEDs in reverse as that would work for me.

Regarding cheaper decoders in the dummy car I was considering that but ended up picking up a load of decoders from Hattons sale, I think they may still be at the basic end since they are 8pin 2fn but I guess for a upgraded HST they should be enough in both ends since I understand the motor is function 0, then the forward/back lights with be 1 and 2?

On the points I'm hoping it will not be an issue as I do not really have many short wheelbase locos that I'm going to use on the DCC layout. I do wonder if the HSTs default pickup configuration may be an issue, or the class 08 may have troubles. I am happy to work on those as improvement projects later though and if stay alive circuits fix those I may look into those.

Thank you both for the advise, I do try to research but its an awful lot to take in so you've been very helpful in providing some clarity.

[96RAF]

No - F0 is 2 functions - fwd and rev. The motor is not a function but a basic comtrol.

[P-Henny]

I guess for a upgraded HST they should be enough in both ends since I understand the motor is function 0, then the forward/back lights with be 1 and 2?

its an awful lot to take in so you've been very helpful in providing some clarity.

 

 

In the context of providing clarity, there is another misleading inference in your reply that I can try to correct.

Physically a decoder has functions, but unfortunately these do not correspond to the logical function numbers that are used to switch things on & off.

Yes one of the decoders function is to control a motor, but the motor control function does not have a logical function number associated with it. Therefore 'function 0' (F0) has nothing to do with the motor.

Take a four function decoder for example (a Hornby R8249 is a four function decoder used as the basis for this reply).

As just stated, the motor is not really considered a logical function and has no F number associated to it.

The first 'Physical' function is the forward white lights connected to the R8249 decoder white wire.

The second 'Physical' function is the reverse red lights connected to the R8249 decoder yellow wire.

The third 'Physical' function is an optional physical function connected to the R8249 decoder green wire.

The fourth 'Physical' function is a second optional physical function connected to the R8249 decoder purple wire.

However, the logical functions (what F numbers switch those physical functions) are mapped differently on the R8249.

The 'Physical' functions (first & second) are for the white and red directional lighting and are linked together to be controlled (switched on & off) by issuing the F0 command on the R8249.

The third 'Physical' function on the R8249 green wire is switched by the F1 command.

Whilst the fourth 'Physical' function on the purple wire is switched by the F2 command.

I need to stress that the assignment of logical F numbers will vary with the decoder brand & model, but F0 is usually always used to switch directional lighting on & off.

For example, a sound decoder usually uses F0 to switch directional lighting on & off and F1 to turn on & off the sounds and F2 up to F28 to control other sound decoder functions. As just stated these F numbers will differ with different decoder brands & models and should be documented in documentation that comes with the decoder or loco model.

Therefore a two function decoder you mention would be motor control with the two physical functions for white and red directional lights switched on & off by F0. There would be no F1 or F2 function.

EDIT: 96RAF got in first whilst I was still typing mine.

[ntpntpntp]

Just a comment about insulated / dead frog points and DC .v. DCC: the method of power makes no difference, how well a loco runs over dead frog points is down to the wheelbase, the pickups, and momentum - regardless of whether it is running on DC or DCC. With DC a free running mechanism with a decent flywheel on the motor can help negotiate such dead spots. With DCC it is possible to add an electronic "stay-alive" module to many decoders and this helps to keep the decoder alive and the motor running if there's a momentary loss of power.

[NSE456]

[Brew Man]

If by, 'interference suppressor' you mean the suppressor capacitor strapped across the motor, and your other locos have these, then snip them out. They are a disaster waiting to happen as a short can take your decoders with them.

[NSE456]

Yeah its that one, and since the picture I posted may not be working its looking rather charred which is why I concluded that may be to blame.

I had heard in the past these may be a problem on DCC, but I kind of assumed that was more related to older converted locos.

I will snip it off and do some more running with the body shell removed, if all goes well I'll load it up with a rake of coaches and do some further testing.

Thank you.

[96RAF]

You are correct that a flashing screen means the Select was rebooting, this is in response to the 1-amp PSU self protecting during an overload or short.

The answer is per above - snip out the capacitor.

[NSE456]

Thank you its working great now. Bit of a scary moment to kick off my DCC experience but at least I know for future and my Mallard is still ok.