Running DC on DCC

[Nodrog1826]

Just one of those daft questions.

I know you can run an analogue loco on DCC, depending on your set up, and other variables.

But I am after a the answer to the question of running DC on a DCC equipped layout, i.e., would disconnecting my Massoth controller and connecting on it's own, say an LGB 1Amp controller to the track, do any damage to point control units, etc that are in situ.

I hasten to add I am not intending to do it, but it's just one of those things that have me wondering, would it all go bang.

 

[Fred2179G]

the answer to the question of running DC on a DCC equipped layout,

When I first looked at DCC many moons ago, it involved constant voltage on the track with electronics in the locos to decide how much power to use. The locos got their commands via a signal imposed on the track voltage.

So as I recall, track DCC is DC+signal. Without the signal, anything with a DCC chip will not pay any attention. So supplying a DCC equipped device with constant or variable DC but no signal shouldn't do any harm.

Or have things moved on since then . . ?

 

[idlemarvel]

In theory you can run a DC loco on DCC powered track on address 0 but it is highly unrecommended.

Not sure what it would do to accessory decoders but I wouldn't risk it. It's better to have accessory decoders on a separate bus if you want to run an analogue DC signal on the track from time to time.

You can run DCC loco on DC powered track if the decoder is configured to handle it.

 

[Fred2179G]

you can run a DC loco on DCC powered track

I think Nodrog (Gordon?) is thinking of supplying variable DC to his track and running a DC locomotive, ignoring all the DCC equipment. His track would not be DCC-powered, as you put it.

This old thread that Google found says much the same:
Is it possible to use the DCC layout to run DC locos?
Most of the answers assume that DCC-power is still on the track. This answer makes a lot more sense, if I understand your question properly:
"If you're not going to convert, you really only have 2 options: 1) a separate loop for DC locos, or 2) a selector switch so that you can power your layout EITHER from a DC power pack or a DCC system, just not at the same time. The drawback of option 2 is that if you forget and try to apply DCC with a DC loco on the track, you may cook something."

In other words, don't leave any DC locos on the track when you switch back to DCC power!

 

[dunnyrail]

I think about this part of his query:-
do any damage to point control units, etc that are in situ.
I am not sure but I do not think that any DCC point control units would be happy with other than DCC particularly if driving Analogue D.C. locomtives with change of direction.

 

[Fred2179G]

I am not sure but I do not think that any DCC point control units would be happy with other than DCC particularly if driving Analogue D.C. locomtives with change of direction.

I don't see why they would care. A DCC chip has a full-wave rectifier on it to account for polarity in the DC, so direction won't matter. If there is no signal, then why would any DCC unit pay any attention?
Where's the DCC experts when you need them! Too busy with July 4th. . .

 

[PhilP]

I don't see why they would care. A DCC chip has a full-wave rectifier on it to account for polarity in the DC, so direction won't matter. If there is no signal, then why would any DCC unit pay any attention?
Where's the DCC experts when you need them! Too busy with July 4th. . .

This is correct IF we are talking analogue DC.
If PWM DC is fed into some DCC equipment, it can become confused.

There is a very slight risk of damage to the equipment.

PhilP

 

[meiningen8]

This is correct IF we are talking analogue DC.
If PWM DC is fed into some DCC equipment, it can become confused.

There is a very slight risk of damage to the equipment.

PhilP

From my limited experience having blown a DCC chip when powered by a PWM controller I would agree Pure DC ok,, PWM DC not so ok

 

[dunnyrail]

Aha so it looks like the LGB 1A Controller as asked in post 1 is unlikely to cause damage, BUT PWM or perhaps other fancy Electronic systems may be an issue.

 

[ntpntpntp]

Accessory decoders fed pure DC will just do nothing in my experience. The PWM question is interesting, I know in the small scales some folk are wary of running loco decoders on PWM DC but I never experienced a problem.

Anyhow, just to avoid any possible problems I wired my accessory decoders on separate circuit to the track power. Both circuits simply joined together at the command station, but I could disconnect track power from DCC in order to run DC (or indeed no track power at all if anyone turned up with a battery or live steamer having uninsulated wheels). The points remained active under DCC.

 

[Diesel2000]

It can be done easily if you set up you layout to switch the power feeders from DCC over to DC. I actually built my layout this way intending to slowly ease into DCC. I ran a separate wiring bus for the switch decoders so those could be controlled via DCC Massoth Nav while the layout was powered by DC. As stated DCC-equipped locos need DC and not PWM DC. It confuses them and they assume its a DCC signal when its not. I had 2 of my 4 loops operable via 15 amp DPDT on/on switch for DCC or DC power (I left the yard and reverse loop DCC-only for obvious reasons).

Ultimately I never really ran anything in DC anymore as I enjoy sound and functions too much and just converted everything to DCC.

 

[LGB333]

Just one of those daft questions.

I know you can run an analogue loco on DCC, depending on your set up, and other variables.

But I am after a the answer to the question of running DC on a DCC equipped layout, i.e., would disconnecting my Massoth controller and connecting on it's own, say an LGB 1Amp controller to the track, do any damage to point control units, etc that are in situ.

I hasten to add I am not intending to do it, but it's just one of those things that have me wondering, would it all go bang.

Nodrog1826 - I asked the Massoth Service Office last year would there be any harm to their DCC switch decoders powered by track connections if I disconnected DCC command station to my track layout and connected DC power to it to operate LGB DC analog locomotives temporarily. The answer was no harm to the switch decoders. So, I assume that would also apply to any brand switch decoders designed for G scale trains. Of course the downside is you can't activate the switches while running DC trains!

 

[Andrew_au]

Anyhow, just to avoid any possible problems I wired my accessory decoders on separate circuit to the track power. Both circuits simply joined together at the command station, but I could disconnect track power from DCC in order to run DC (or indeed no track power at all if anyone turned up with a battery or live steamer having uninsulated wheels). The points remained active under DCC.

That's quite clever.

I know a lot of the smaller scales run a separate accessory bus, but I believe that this is more to do with power transmission reliability through the rails. G scale rails are big enough to transmit power and signal without much risk of loss, but having an accessory bus means you can de-power some or all of the rails without also disabling the accessories.

That said, it's certainly convenient to use something like a LGB 55524 (or cheaper alternative) to drive a distant turnout without needing to run separate wiring.

 

[dunnyrail]

Nodrog1826 - I asked the Massoth Service Office last year would there be any harm to their DCC switch decoders powered by track connections if I disconnected DCC command station to my track layout and connected DC power to it to operate LGB DC analog locomotives temporarily. The answer was no harm to the switch decoders. So, I assume that would also apply to any brand switch decoders designed for G scale trains. Of course the downside is you can't activate the switches while running DC trains!

Hm ok not something I do not like to do, fully ok according to all LGB and some other DCC systems but why not run your DC locomotives (1 at a time obviously)on address 0?

 

[PhilP]

Hm ok not something I do not like to do, fully ok according to all LGB and some other DCC systems but why not run your DC locomotives (1 at a time obviously)on address 0?

Because it makes a horrible noise, and can fry the motor(s).
Just, electrically, not a good practice..

PhilP

 

[dunnyrail]

Because it makes a horrible noise, and can fry the motor(s).
Just, electrically, not a good practice..

PhilP

I know that, we have this conversation with regular monotony.

But it is an option and was suggested in the old days by LGB. We did have a couple of Bachmann Locomotives on 0 all day at the Ruschbahn (1 at a time of course) plus the odd unchipoed LGB Locomotive all day and no damage ensued. And yes the noise is an orrible electronic whooshing wizzing sort of sound even when not moving.

As I said I do not like to do it but it is something that is, has and will de done by many as it is in the LGB and others instruction manuals. Though not sure if LGB-Maerklin say anything about it.

 

[Greg Elmassian]

The answer was in post #7...

This is not about the "address 0" feature, a.k.a. "zero stretching" in old DCC systems, which seems to keep coming back in this thread...

It's about putting DC on the rails on a DCC layout (instead of DCC) and if other items - specifically switch/turnout controllers would be damaged by DC.

The answer is NO, BUT!!! If you use a "DC" supply that actually puts out PWM, then DCC devices can become confused, and depending on the brand, damage can ensue. (post 8, and also my experience)


So, if it was me, answering the question...

1. If I was to put "pure" DC on the rails, don't worry, any DCC equipment connected to the rails will ignore it.
2. If I was to put PWM (pulse width modulated) power to the rails, I would test that separately on the devices I had connected.

In my case, I use Digitrax DS-64 accessory modules to control my switches/turnouts. They ignored the PWM signal put out by my MRC Power 10 "transformer".

Greg

 

[Nodrog1826]

Thanks for the answers.

So i have an idea that it's safe going forwards, should i choose/need to do it at some point.

One thing i had considered is getting one of the new Massoth LED light control modules, when they come out and finances allow,
but was wondering if i would need a dpdt circuit to run the lights as a night time garden feature from the batteries when the track is not powered.

 

[PhilP]

I would advocate a separate supply for lights..
Depending what you would like to do, we might be able to make suggestions..

Perhaps a different thread, on lights, and their control?

PhilP

 

[Greg Elmassian]

I'd turn on my system and run the lights from the rails, rather than add extra expense and maintenance of batteries.

If it works with DCC on, what is the issue?

Greg