DCC and DC Dual Capability Layout

[Isambard]

Our HO modular club is poised on the point of introducing DCC to the club layout, while maintaining the current DC capability. We have bought a Digitrax PS 2012 20 A. Power Suppply, a DCS 100 Command Station /Booster and two PM42 Power Managers (allowing creation of eight power districts) and a number of Digitrax IR capable throttles and receivers.

Our currrent cab controlled DC layout consists of two mainline loops plus a centre staging yard connected by a wye and crossovers to the two mainline loops. Each of the mainline loops is powered by its own source and constitutes a single power district. The yard can be powered from a local yard power unit or by connecting to one of the mainline loops and that loop's cab control.

Some of the modules also have local control power for local tracks that can be switched to control the mainline sections on that module. Our current power bus is unreliable and needs replacing in any case, as does the mainline and local wiring on some modules.

We intend separate DCC and DC operating sesssions, not mixed.

The problem that we are now working on is how to arrange new power bus(es) that will cater for the current DC configuration while also doing so for the eight DCC power districts, while minimizing amount of bus wiring, connectors, effort etc etc, and providing for fail safe/fool proof protection to equipment, whether DCC, main DC main or local module DC.

One solution is not to go there; scrap the idea of maintaining DC for those few members present or future who want to run DC locos, thus greatly simplifying our task in time and effort, shortening the time we get DCC up and running reliably.

Another (partial) solution could be to limit DC operations to certain parts of the layout e.g. mainline loops and yard, not local tracks.

Another solution could be to go DCC only and allow DC loco operation at specific sessions. With one command station this would presumably limit to one DC loco at a time?

Comments welcomed from those who have been there before.

[Anonymous]

the great thing about DCC is that if you are converting a DC layout over it's not hard at all and can pretty much keep the same wiring.... and most DCC systems allow you to use 1 DC Locomotive with it by having it on a certain channel or connecting another source to the actual DCC unit.

so all of your clubs DC only guys should be alright if you go to DCC.

[Anonymous]

Whew... I was thinking this is for a home set up. But a big time club.. that is a tough question.

If this was a home layout I would just leave all the DC infrastructure intact and run new a new bus for DCC next to the old DC bus under the tracks. In effect simply supply a route for the DCC to feed the rails, switches and reversers (If any)

You could create dedicated "dead" tracks for analog DC equiptment to hide away from the DCC activity. Run that analog engine onto that dead track and kill the current. Then the rest of the layout can run DCC until everyone was done with the session.

It should not matter what is ALREADY on the layout when you show up to hook that brand new DCC system on it. Just check your reversing loops and switches with it's own power feed away from the old Analog infrastructure.

That is the extent of my idea. I feel that I am not qualified to address such a large issue facing your club.

[rrinker]

The EASIEST thing to do would be to create 8 DC blocks - exactly the same as the DCC power districts. All you need to do is put a DPDT toggle on each section. One side will go to the output of the PM42. The other side will go to the DC power supply. The center will go to the track section.
This is obviously a bit limited in DC operation, but anything more will require more complex wiring to switch blocks between DC and DCC power. I would recommend all or nothing - if you are trying to run both DC and DCC at the same time and a loco crosses the gap between a section on DC and a section on DCC, you could damage your decoders, booster, PM42, or loco motor.
And yes, with only one command station you can only control one DC loco on DCC at a time. You can RUN as many as you have power for, but they will be controlled at the same time.

--Randy

[Isambard]

QUOTE: Originally posted by rrinker

The EASIEST thing to do would be to create 8 DC blocks - exactly the same as the DCC power districts. All you need to do is put a DPDT toggle on each section. One side will go to the output of the PM42. The other side will go to the DC power supply. The center will go to the track section.
This is obviously a bit limited in DC operation, but anything more will require more complex wiring to switch blocks between DC and DCC power. I would recommend all or nothing - if you are trying to run both DC and DCC at the same time and a loco crosses the gap between a section on DC and a section on DCC, you could damage your decoders, booster, PM42, or loco motor.
And yes, with only one command station you can only control one DC loco on DCC at a time. You can RUN as many as you have power for, but they will be controlled at the same time.

--Randy

Thanks Randy.

A further question for you or others. Being a modular club (23 modules, 4 ft long, for total of 92 ft.) we want our power bus wires to be robust, readily disconnectable/connectable and foolproof. We'll have bus wires running from the two PM42's to the eight power districts and between modules-configuration yet to be determined, also whether we'll maintain a dual DC and DCC capability (separate operating sessions).
We are currently looking at making up bus lengths using either two or four conductor 14 gauge stranded plastic sheathed wire, as used for house wiring, or power tool extension cord. Bus ends would be polarized plugs and track feeder connections to bus at mid module points would be soldered spade lugs to rugged terminal blocks.
We'd appreciate comments as to this approach or alternative solutions.
[:)]

[rrinker]

SOunds reasonable, although you might want to use #12 wire instead of #14 over those lengths.
Just do NOT use any sort of normal 120v or 220v plugs and sockets for connections - all it takes is one person to mistakenly plug it in to an outlet and at best damage some equipment and at worst electrocute someone.
There was a modular S scale layout at the local train show today. They had one line hooked to a standard AC transformer for stock Flyer locos, and the other main was connected to a Digitrax system running converted locos. As a modular group, that's another way to handle DC/DCC, if you have a 2-track main. One of the members there said most of the club has converted to DCC but they have a few die-hard holdouts who want to continue the Flyer AC.

--Randy

[mcouvillion]

Isambard,

I've worked with two modular layouts that essentially address all of your questions.

DC/DCC on same wiring: From what you described, using a switch to change from DC to DCC and back would work in all areas except the wye. One leg of the wye will need an automated polarity changer for DCC, and a DPDT switch for DC. Shouldn't be too hard for someone with a little wiring knowledge to figure this one out.

I selected 4-conductor connectors from Mouser for the two buses under our layout. These locked when connected and were a male/female pair. One side had tabs so that it could be attached to the module. The wires are 14 AWG and paired yellow/gray and orange/blue. We used suitcase connectors to connect the track feeders to the bus and to connect secondary buses to the main bus. We have not had any voltage drop problems, but our layout is a little smaller than yours. You could always use a booster and circuit breakers on further areas of the layout to give you more power districts and less susceptibility to shorts, since the command signal travels on the LocoNet (or equivalent) until it is dropped on the power bus. We put terminal strips at each end of the modules, using spade lugs at the terminal strips.

The pigtails for the connections between modules were built to a standard at the bench, one male with wires about 18" long and one female, recessed under the table, with wires about 6" long to reach the terminal strip. We tried to build it idiot-proof. I have used trailer plugs on the other layout, and it is supposed to be idiot-proof, but once, an idiot figured out how to circumvent the wiring. We had to change it slightly.

You should be fine as long as you do not have common rail wiring. With color-coded wire pairs, if you use same-colored drops from the rails, you'll be hard-pressed to have a wiring problem you can't readily figure out.

Send me an e-mail if you want the specific part numbers of items we used. Guys who are not the least mechanical or electrical can set up and get the layout running in 45 minutes.

Mark C.

[Isambard]

QUOTE: Originally posted by mcouvillion

Isambard,

I've worked with two modular layouts that essentially address all of your questions.

DC/DCC on same wiring: From what you described, using a switch to change from DC to DCC and back would work in all areas except the wye. One leg of the wye will need an automated polarity changer for DCC, and a DPDT switch for DC. Shouldn't be too hard for someone with a little wiring knowledge to figure this one out.

Mark C.

Thanks for that info Mark. We'll use one of the PM42 outputs in auto reverser mode for the wye section, another for the programming track.

On Saturday we substituted my Digitrax DB150 Command Station/Booster for the club DC supply and ran both a decoder equipped 2-8-0 and a no-decoder 2-8-0 around our outer loop (92 ft long continuous loop power bus, power bus fed from power supply at one point only, track feeders every four feet or so). The first runs went well, the second runs not so well.

The decoder equipped 2-8-0 hiccuped and stalled a number of times, particularly when furthest away from the DB150 i.e. around 40-42 feet, then went dead. This is probably confirmation that we have work to do on new bus wiring and track connections, also probably that I've rushed too fast and have fried my first decoder. [:I]