# DCC Questions



## PhillipL (May 5, 2012)

All,

I have always been a DC railroader. I have accumulated a fair amount of DC European and US locomotives. Over the last year or so I have purchased three Bachmann DCC locomotives (GP7, GP9 and RS3) that I am running in DC mode. 

I have looked at a couple of DCC starter systems at modeltrainstuff.com. Here is my question, how are DCC system connected to the tracks. Are they connected the traditional DC way (two wires)? Also, is it possible to disconnect the DCC system and connect my DC transformer to run my DC locomotives? 

I am not necessarily interested in all kind of fancy functions and I doubt my DCC will go much beyond Bachmann and some Walthers Mainline due to a very small hobby budget.


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## gregc (Apr 25, 2015)

you can put a dpdt switch to connect either a DCC or DC throttle


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## flyboy2610 (Jan 20, 2010)

That's how I have my test track set up in the workshop. There's no reason you couldn't power a layout that way.


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## PhillipL (May 5, 2012)

I have been reading up on one of the DCC starter systems (Digitrax Zephyr Xtra Complete DCC Starter Set System with 3.0 Amp Power Supply). According to Digitrax website, I can set the system to 00 and then be able to operate a regular DC locomotive. Would this be safe for DC locomotives?


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## D&J Railroad (Oct 4, 2013)

That procedure will allow you to control DC locomotives on the DCC system, however, that imposes more wear on your DC locomotive motor than straight DC.
DCC is comprised of a square sine wave of AC power. Each square wave will carry the digital command to control the decoder on board the locomotive.
When 00 is dialed up on the DCC system, it will skew the sine wave one way or the other so that the DC motor will see it as a DC power source. The problem with this type of power application is that the high pitched AC signal sends continuous pulses to the DC motor which produce heat. Sorta like if you were turning the throttle to forward and backward at over 100 times a second. If you place a DC loco on the track without dialing 00, you can hear the motor responding to the ever present AC sine wave. This is referred to as singing.
You can operate like that but I wouldn't recommend doing it for very long, i.e. 5 minutes or more.


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## ncrc5315 (Jan 25, 2014)

You can operate it that way, as long as you keep the locomotive moving. When sitting at "idle", the system is sending a pulse to the positive side, then an equal pulse to the negative side. When the loco is moving, there are more pulses on one "side" then the other, which caused the loco to move. Yes it can be done, and it is safe, but you need to keep the loco moving, the faster the better.


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## gregc (Apr 25, 2015)

to be clear ... DCC applies a constant (~14v) to the track but alternates it's polarity. The time between polarity reversals communicates a 1/0 to a decoder creating a packet.

without a motor turning, a turning motor produces back EMF, the motor current is limited by the resistance of the wires. as others have said, an alternating voltages pushes the motor back and forth so that it never turns. 

This large current generates heat which can melt the wire insulation and damage the motor.

DCC can drive a DC motor by maintaining one polarity for an extended period of time. the polarity determines the direction and the percentage of time the polarity is unchanged results in an average voltage that is not zero causing a DC motor to turn. But at the same time, voltage of the opposite polarity is present, forcing the motor in the opposite direction opposing this motion. This results in more current than would occur if the motor were operated with pure DC.

this approach is certainly a compromise and not the best way to operate a DC locomotive along with other DCC locomotives at the same time. 

it would be better (less damaging) to switch to a DC throttle to operate a DC locomotive or to have blocks that can be connected to either a DC or DCC throttle.


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## Cycleops (Dec 6, 2014)

You could do as gregc suggests and have a switchable DCC/DC system but with decoders being so cheap nowadays its probably safer to try and convert your existing locos to avoid any nasty mishaps.


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## DonR (Oct 18, 2012)

You will be glad you went with DCC. To control more than
one train on your DC layout you need 2 or more
power packs, a complex set of switches, and a lot of
patience.

With DCC, you have 2 wires to the track (actually to
the track bus). Each loco has a unique address (often
the road number) You push a button to start the
loco, get it running, then as it continues you push a
button for the 2nd (or 3rd, or 4th)...You use the
controller as you do the TV remote.

But if you plan to run some of your older DC locos 
you should do as others have advised; Set up a
switch that one way powers the track with DCC and
the other way with DC. Then over time you can
convert your favorite DC locos, non sound decoders
sell for more or less than 20.00 each. Installation
in most locos is a simple couple of hours.

Incidentally, NMRA standards means you can use
one make controller and decoders of any of the
other makes. 

Don


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## CTValleyRR (Jul 26, 2014)

Replacing a DC controller with a DCC one is as simple as disconnecting the wires from the DC pack and connecting them to the DCC unit.

The problem then becomes what to do with your locos that aren't DCC capable. As others have noted, you can run ONE at a time using the Digitrax, but it's hard on the motor. You can set up an A-B switch and chose which type of power is being provided to the tracks. Or you can convert all your old locos.

If you're a decent hand with a soldering iron, installing your own isn't that hard. You may have to isolate the motor from the frame and add resistors for any lighting, but that's not hard either.

I'd recommend setting up the selector switch and gradually converting your locos. That worked well for me.

I think you will definitely prefer DCC once you get into it!


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## Lemonhawk (Sep 24, 2013)

I always worry about using a selector switch to switch between DC and DCC. If you inadvertently leave a DC locomotive on the track and switch to DCC, you'll probably notice the mistake when the DC locomotive starts to smell and becomes toast! You could have a separate (completely isolated) DC loop, that's a little safer. DCC decoder are inexpensive if you don't include sound, and if most of you locomotives are DCC ready, it really easy to convert them to DCC, biggest problem will be getting the shell off! You can't go wrong with the very expandable Digitrax system, I would sort of ignore the mention of using address 00 to control a DC locomotive on a DCC track. Whatever DCC system you get its unlikely that you will go back to DC, its just too much fun using a DCC system!


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## PhillipL (May 5, 2012)

All, Thank you for the information. I am going to consider everything discussed here. I am leaning towards delaying the switch to DCC for now. I have a fair amount of DC locomotives and only three DCC ones. I do really appreciate what has been shared, I really do not want to damage any DC locomotives especially the older ROCO ones.


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## BCFx (Jul 22, 2018)

gregc said:


> you can put a dpdt switch to connect either a DCC or DC throttle


This is what I'm doing. I grew up with DC so my collection is all DC. As I buy new, I'm buying DCC and selling my older DC locos. The newer stuff is generally better detailed and runs smoother. 

My layout is being wired in blocks with dual cab control. Cab A will be my old MRC Tech II that still works great. Cab B will be my new MRC Prodigy DCC system.


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## DonR (Oct 18, 2012)

BCFx said:


> This is what I'm doing. I grew up with DC so my collection is all DC. As I buy new, I'm buying DCC and selling my older DC locos. The newer stuff is generally better detailed and runs smoother.
> 
> My layout is being wired in blocks with dual cab control. Cab A will be my old MRC Tech II that still works great. Cab B will be my new MRC Prodigy DCC system.


Having two very incompatible power systems on
the same layout can result in damage to the DCC
system. This can happen if a loco crosses between
the DC track and the DCC track. The loco wheels
will connect the two systems and poof no more
magic dragon.

Even a power routing turnout can make a
connection and cause damage.

Consider removing any turnout that would 
permit loco movement from one system to
the other.

Or better yet, use the recommended double pole
double throw (DPDT) switch to power the entire layout
with EITHER DC or DCC but NOT both.

Don


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## beepjuice (Sep 17, 2014)

If you do get the DCC, I'd recommend the Digitrax Zephyr. I got it and it's very easy to run. If needed, the customer service is the best. Phone calls always answered! Plus, there are many tutorial videos on Youtube.


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## CTValleyRR (Jul 26, 2014)

beepjuice said:


> If you do get the DCC, I'd recommend the Digitrax Zephyr. I got it and it's very easy to run. If needed, the customer service is the best. Phone calls always answered! Plus, there are many tutorial videos on Youtube.


I would recommend that you consider the offerings from the big 3: Digitrax, MRC, and NCE. The same positives that beepjuice notes above apply equally to all 3. It really boils down to personal preference. If you can try before you buy, so much the better.

Mine is for MRC, but you won't go wrong with any of them.


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## tankist (Jun 11, 2009)

zephyr is a respectable system , but in my opinion it has several "no go " shortcomings. NCE with their powercab makes for a better overall stater system in my opinion. 

MRC was my primer into DCC, I do not see reasons to chose it over the above two. I remember it having many features with proprietary implemeimplementation, making it not usable with anything else on market. Perhaps things changed through the years, not following on their prodigy system updates.

As for running both DC and DCC Interchangegably it sure can be done. Will make for extra step setting things up everytime. Many DCC locomotives however will be configured out of factory to run on DC . They will not crawl well (not enough V at low end to power the system), but as soon as there is enough power on the rails they will interpret it into speed changes. My Tsunami sound decofer equipped engine does just that (sound works too)

Good luck


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## ncrc5315 (Jan 25, 2014)

I would also look at the ESu Cab Control system.


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## Cycleops (Dec 6, 2014)

ncrc5315 said:


> I would also look at the ESu Cab Control system.


Nice controller if you've got the dosh. Its static so you can't move it around the layout.


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## MichaelE (Mar 7, 2018)

It doesn't cost as much as I thought it would.

The cab is wireless so I don't understand your statement.


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## CTValleyRR (Jul 26, 2014)

And the takeaway is that the fans of all of these systems will come out and support the one that they prefer.

As I said, it's a matter of personal choice. Contrary to what Tankist says, there is nothing proprietary about MRC's offerings that is seriously limiting. You have to use THEIR wireless interface if you want to hook in a personal computer, but I'd recommend purchasing all the major system components from the same manufacturer in any case.

And the things that he considers "no go" shortcomings of a Digitrax may be things that you actually prefer.

There are no technological or performance shortcomings with any of these systems, but the look and feel, ease of performing certain functions, and the specifics of set-up and operation are different (sometimes markedly so), which is why I say try before you buy if at all possible.


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## Genetk44 (Feb 26, 2016)

CTValleyRR said:


> And the takeaway is that the fans of all of these systems will come out and support the one that they prefer.
> 
> As I said, it's a matter of personal choice. Contrary to what Tankist says, there is nothing proprietary about MRC's offerings that is seriously limiting. You have to use THEIR wireless interface if you want to hook in a personal computer, but I'd recommend purchasing all the major system components from the same manufacturer in any case.
> 
> ...


 :smilie_daumenpos::smilie_daumenpos:


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## tankist (Jun 11, 2009)

> Contrary to what Tankist says, there is nothing proprietary about MRC's offerings that is seriously limiting.


MRC connects to PC yes, but it did not interface with loconet or any other equipment, all it did is provide its own very limiting software for decoder programing (that couldn't program my particular digitrax decoders for some reason) and rudimentary train OP. its been almost a decade and perhaps things changed but I sold mine not because i didn't like the looks (i actually would have preferred to use the knob style throttle instead of NCE style scroll wheel) but because not having the functionality i needed . i've yet to see a big club that uses, but i guess it can be all that is needed for just running a few trains at home.

Zephyr the absolute position of the handle commanding the speed is the biggest turn off for me (id rather have a free rotating knob). the green numerical screen is limited to the info it can display not making for friendly operation, It was already dated on release, let alone 2018. and then the choice of tiny tactile buttons when a rubber dome is also dirt cheap to make. 
their boosters and com stations however are solid as well as hardware for transponders and signalling.



> but I'd recommend purchasing all the major system components from the same manufacturer in any case.


 I don't see why. two major components: command station and decoders. owning an NCE system i see no reason whatsoever to not use Digitrax decoders for new installs. if i come across bunch of TCS decoders i would not hesitate to install those either. and when you get into minor niche stuff like detection and signalling its hard to beat offerings by team digital (fully compliant with locoN BTW).

i don't think "fan" or "brand loyalty" is applicable here. any given system either fulfils the requirements of a particular user or it doesn't.


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## Cycleops (Dec 6, 2014)

Sorry I thought you were referring to the console version. Didn't know there was now a cab version.


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## CTValleyRR (Jul 26, 2014)

tankist said:


> MRC connects to PC yes, but it did not interface with loconet or any other equipment, all it did is provide its own very limiting software for decoder programing (that couldn't program my particular digitrax decoders for some reason) and rudimentary train OP. its been almost a decade and perhaps things changed but I sold mine not because i didn't like the looks (i actually would have preferred to use the knob style throttle instead of NCE style scroll wheel) but because not having the functionality i needed . i've yet to see a big club that uses, but i guess it can be all that is needed for just running a few trains at home.
> 
> Zephyr the absolute position of the handle commanding the speed is the biggest turn off for me (id rather have a free rotating knob). the green numerical screen is limited to the info it can display not making for friendly operation, It was already dated on release, let alone 2018. and then the choice of tiny tactile buttons when a rubber dome is also dirt cheap to make.
> their boosters and com stations however are solid as well as hardware for transponders and signalling.
> ...


Decoders from any manufacturer can be used with any system. When I refer to major components, I'm talking about the parts "between the wall plug and the rails", including boosters but excluding reverse loop controllers.

As far as the rest goes, you are entitled to you opinions with regard to the merits and drawbacks of each of the systems.

That doesn't change the fact that each user has his own set of requirements and preferences, and should base his evaluation on his own assessment of that, not everyone else touting the system they own.


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## J.Albert1949 (Feb 3, 2018)

The OP should spend some time on YouTube watching reviews of the various systems "out there"...


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