# DCC for G Gauge, advice required.



## Trevor (May 8, 2012)

Hi
I am doing some investigation on DCC for G scale on behalf of my dad who is looking at starting up a new G gauge layout; we have plenty of experience with N & OO (HO) gauges but not G or in setting up DCC. Although I have quite extensive knowledge of how it works I have never used or set one up.
Please could people answer the following questions, any other useful tips practically related to G gauge & DCC:

1) We need to work out what the total power requirement is, what is the best & worst case for power consumption (Amps at G gauge voltage) of an average to large size G gauge engine (4-6-0). I understand OO (HO) is about 0.5-1A depending if it’s new or old, so I gauss G gauge would be 1-1.5A per motor depending on size?

2) Is CV read back that important, can we manage without to start with or if we are not that interested in sound.

3) We are looking at the ‘Super Empire Builder Xtra Set - Duplex Radio’ as one possible option, can you use a separate programing track with this? It has the same number of connecters as the Zephyr & Super Chief but the info suggests it can only do main line programing.

4) What things to look for in reasonable price decoders, and what power rating should we use.

5) Your recommendations for DCC starter set for the following layout – Outside layout with 30-40m (100-130 ft) of brass track and 6 turnouts as of the current design, more turnouts may be added during 1st layout. In the first 5 years there will probably be a maximum of 3 average to large size engines, probably all running at once, with long wheelbase coaches & box cars, all US style.

Thanks for your help.
Trevor


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## lownote (Jan 3, 2008)

I would go for ten amps. I have a similar sized layout, about 1/2 or so stainless steel, four DCC controlled switches. I use the NCE ten amp system and most of the time it's enough power. Occasionally I get a shut down, if i'm running a lot. I have sound decoders in every loco and lights in everything that should have lights--seven passenger cars, cabeese, etc. But I've converted all the lights to LEDs to reduce current draw. We also run some led lights for buildings from the track. I would say ten amps is fine for me, but any less would be a problem. As you probably know, current draw varies with the length of the train and with grade. You could get away with less, but not all the time, I would argue.

It's usually argued that USA Trains locos are more power hungry than others. I've not always found that to be the case, but people more knowledgeable than me have. NCE makes a special 8 amp decoder just for USA trains

I've used the "large scale" decoders from NCE, Digitrax, QSI, ESU, and Lenz. When it comes to non-sound decoders, I think I like the Digittrax DG583 best. It's smooth at low speeds, quiet, and seems to have plenty of power. 

As to sound decoders for large scale, you can find them from ESU, Massoth, Zimo, and sort of for digitrax. QSI has been promising a new large scale decoder for about two years--it's not here yet but may be soon. QSI has the best collection of American loco sounds, I think. 


There are two excellent page sof DCC tips--George Schreyer's: (http://www.girr.org/girr/tips/tips.html) and Greg Elmassian's (http://www.elmassian.com/trains)


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## Cougar Rock Rail (Jan 2, 2008)

You asked about best/worst case on amperage requirements. I'm sure Greg will give you the super-power-user perspective, so I thought I'd give you mine at the other end of the spectrum. I run all LGB, Swiss prototype engines, so all are efficient Buehler motors. I can have three double motor locos with sound, cars with lights, running at relatively slow prototypical speeds and still not trip my LGB MTSIII central station running only 5Amps. I use wireless Massoth Navigators for control. Running a single train (with sound and lit cars) usually consumes between 0.7 and 1.5 amp. My track is all LGB brass, grades


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## JPCaputo (Jul 26, 2009)

I am fairly new to DCC, but can you use the Dcc system for HO/N scale but run a booster for large scale from the output? 

JP


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## Greg Elmassian (Jan 3, 2008)

1. There is a wide range of power used by large scale locos, from LGB and small speeders and rail trucks to large locos that run pittman motors. Figure under an amp to an amp for LGB, and maybe 1.5 to 2 amps for larger locos under load. So your guess is good for the best case.


2. I'm guessing that your CV readback means bidirectional communication on the main line, like Digitrax has. (you can always read back CV settings on the program track).... the readback is neat for automated systems, and eventually the NMRA will decide on the standard well enough to use it, but you don't need it for sound or any non-automated systems. Note well, having an automated system does not need that feature either, you can use inexpensive block occupancy detectors to do this.

3. The duplex radio throttles are much better than the simplex ones. My NCE is duplex. I find it hard to believe you would not have any way to have a programming track output from the command station.

4. Don't get too wound up in the amperage of the decoder as the driving force for decisions. Stay away from cheap decoders, they don't last. You normally want a decoder that can handle over 3 amps, but there is a wide selection of decoders, so pick what is appropriate for the loco. Ask here, there's lots of expertise to help you. Look more at the features, do you need extra lighting outputs? sound? direct control of the smoke unit to make it puff in sync with the drivers?


Overall, 5 amps on your booster will be marginal with more than 2 locos. 8 amps will suit many people well. I use 10 amps, and will be going a bit more, but I run long trains, several at a time, and lighted passenger cars. One train that is pictured on my main train page on my site is 3 Aristo e8's and 10 USAT streamliners, all lit with the factory lights. This train pulls 9.7 amps up my extreme 3.4% grade. Now that's a worst case train, the locos are 1/3 of the power, about 6 amps is from the lighted cars. I'll change the incandescent bulbs to LEDs and drop those 6 amps to about 2.


Hope this helps,

Greg 



Posted By Trevor on 08 May 2012 03:46 PM 
Hi
I am doing some investigation on DCC for G scale on behalf of my dad who is looking at starting up a new G gauge layout; we have plenty of experience with N & OO (HO) gauges but not G or in setting up DCC. Although I have quite extensive knowledge of how it works I have never used or set one up.
Please could people answer the following questions, any other useful tips practically related to G gauge & DCC:

1) We need to work out what the total power requirement is, what is the best & worst case for power consumption (Amps at G gauge voltage) of an average to large size G gauge engine (4-6-0). I understand OO (HO) is about 0.5-1A depending if it’s new or old, so I gauss G gauge would be 1-1.5A per motor depending on size?

2) Is CV read back that important, can we manage without to start with or if we are not that interested in sound.

3) We are looking at the ‘Super Empire Builder Xtra Set - Duplex Radio’ as one possible option, can you use a separate programing track with this? It has the same number of connecters as the Zephyr & Super Chief but the info suggests it can only do main line programing.

4) What things to look for in reasonable price decoders, and what power rating should we use.

5) Your recommendations for DCC starter set for the following layout – Outside layout with 30-40m (100-130 ft) of brass track and 6 turnouts as of the current design, more turnouts may be added during 1st layout. In the first 5 years there will probably be a maximum of 3 average to large size engines, probably all running at once, with long wheelbase coaches & box cars, all US style.

Thanks for your help.
Trevor


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## Trevor (May 8, 2012)

Hi
Thanks for every ones comments so far, I have a further question on power requirement.
Assuming I get a 5A starter DCC set, when we buy more locos (some of which have two motors), we would also get another 5A booster and split the large circular layout in half into two power districts.
We still want to do double or triple headed trains, but what do other people do when the total power required by this train exceeds the available power in each power districts.
2 engines with 2 motors each = 4A-6A
Are we better off going for a 10A starter kit, with its additional risks of damaging rolling stock in the case of derailments?
Trevor


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## Greg Elmassian (Jan 3, 2008)

First, if you have a train that uses one loco and pulls 2 amps... if you take the SAME train and double head, the total amps will only be slightly over 2 amps, like maybe 2.3 amps. Why? 

Because the current drawn is mostly proportional to the load. 

Now, of course, if you double head, AND pull twice the cars, then you would be looking at 4 amps. 

So you need to think about what you will do. 

Please also remember that lighted passenger cars will draw a fair amount of current... I have one train that pulls 9.7 amps worst case, but it is 10 lighted passenger cars (which use very inefficient bulbs, stock) and 3 Aristo E8 locos up a 3.4% grade. 

This is an idea to give you the worst case. 

Bottom line, if you have any grades over 1%, or will pull long trains, or triple head, go for 10 amps right off, you will thank me. (The 3.4% grade is in the background, not the small loop you see)





Greg


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## mbendebba (Jan 22, 2011)

Trevor: 
The cost of setting up a DCC system in generally high regardless of which system you choose, systems that appear to be relatively inexpensive at first glance can endup cost you about the same or more than an initially expensive system. 
Two 5 amps transformers, a central station and a boooster cost more than a 10amp system, regardless of who makes the sytem. 
I am a Massoth dealer and I sell 2 wireless stater sets that feature just about anything you would want in a DCC system. 

Mohammed 
http://www.massothusa.com


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## adelmo (Jan 2, 2008)

Hey Trevor, 

If you like the NCE handheld, I would recommend the NCE 10amp wireless set over the 5amp. 

This will allow for future power additions and also allows for track voltage adjustment. 

The NCE 10 amp set is your best bang for your buck IMO. Made in USA too! 

Alan


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## krs (Feb 29, 2008)

Posted By Trevor on 11 May 2012 06:10 AM 
Hi
Thanks for every ones comments so far, I have a further question on power requirement.
Assuming I get a 5A starter DCC set, when we buy more locos (some of which have two motors), we would also get another 5A booster and split the large circular layout in half into two power districts.
We still want to do double or triple headed trains, but what do other people do when the total power required by this train exceeds the available power in each power districts.
2 engines with 2 motors each = 4A-6A
Are we better off going for a 10A starter kit, with its additional risks of damaging rolling stock in the case of derailments?
Trevor

I wouldn't go for anything less than 10 amps especially if you're going to run passenger trains with lighted cars and/or locos with smoke and/or sound all of which require additional power.
The sweet spot for me is actually a 15 amp system and multiple 15 amp boosters as the power requirements grow.


As to the risk of damaging equipment with the higher output units - that depends a lot on how sophisticated the shut down protection is.
For low output systems, say up to 5 amps, a very basic overcurrent shut down is probably adequate - but when one gets to the 10, 12, 15 and 20 amp range, I think one needs a more sophisticated shut down circuit - one that detects when a short circuit has occurred well before the maximum current output of the system or booster is reached.
Trouble is that DCC system/booster manufacturers don't provide much information in that area.

Knut


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## Cougar Rock Rail (Jan 2, 2008)

Regarding the sophistication of the shutdown/short circuit detection, the Massoth is the only one I'm aware of that has adjustable timing. This is one of the reasons you pay a little more for it but you get what you pay for in my opinion. 

Keith


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## krs (Feb 29, 2008)

Keith, 

By "sophisticated shut down circuit" I was thinking of a design where a short circuit is detected at a current level well below the maximum output current capability of the system or booster. 
Say your running a small train that draws only an amp or so to run, train derails causing a short. Well one doesn't rally want the output current of a 10 amp system to have to rise to above 10 amps before shutting down the system but that's exactly what systems with very basic short circuit protection would do. 
Being able to adjust the short circuit trip time is nice, but I could never understand why manufacturers chose the delay intervals to be that long. 
Last time I looked at Massoth, the available settings were 2, 3, 4, 6, 8 and 10 seconds - do I really want to wait 10 seconds after a short is detected before the system shuts down? Or even 2 seconds? 
One sometimes does get momentary shorts running through certain track work but even 2 seconds to allow for that is stretching it, I think. 

*PS: These shut down times are no longer correct! - see Keith's post below.* 


Haven't really done any testing though, maybe Massoth has and that's where these setting options come from. 
I remember the 20 amp booster by Perandones has a specified short circuit shut down time of 4 milliseconds. With that one better not have any momentary shorts during normal operation. But that booster was used in large HO scale layouts where locos can take much less of a fault current before being damaged. 

Knut


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## Greg Elmassian (Jan 3, 2008)

I use DCC specialties breakers / autoreversers... they are "way smart" and not only adjustable, but programable. For me they do a great job of discriminating between a short and a momentary surge. 

Greg


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## Cougar Rock Rail (Jan 2, 2008)

Knut, not sure where you got those numbers from, but Massoth is adjustable from 0.1 to 0.8 seconds. They recommend 0.4seconds in the manual as a good starting point. 


Keith


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## krs (Feb 29, 2008)

Posted By Cougar Rock Rail on 11 May 2012 12:32 PM 
Knut, not sure where you got those numbers from, but Massoth is adjustable from 0.1 to 0.8 seconds. They recommend 0.4seconds in the manual as a good starting point. 


Keith 
Those were the specs of the original DiMax 1200 system that I had picked up when doing a spec comparison of the various DCC systems suitable for Large Scale.
But that was years ago.
The range now that you specified makes much more sense.

Knut


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## Dan Pierce (Jan 2, 2008)

The Zimo station has a programmable current limit and is set from the hand held unit.


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## Axel Tillmann (Jan 10, 2008)

Personally I would test 20 short circuit protection before I commit to buy the system (of course only when the system specs state that it has short circuit protection







)

Connect the DCC system to the track and put a metal bar over the track. It should have tripped the system, then lift the bar and repeat (at least 20 times). That will show you how good the short circuit protection is. You will find that some of the systems that claim they have short cirucit protection haaaavvvve it but still burn up.









I have created probably more than 100 short circuit while working on my layout, or on my test tracks (all coinicidently of course), and my system is still standing


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## Dennis Cherry (Feb 16, 2008)

Posted By Axel Tillmann on 21 May 2012 04:09 AM 
Personally I would test 20 short circuit protection before I commit to buy the system (of course only when the system specs state that it has short circuit protection







)

Connect the DCC system to the track and put a metal bar over the track. It should have tripped the system, then lift the bar and repeat (at least 20 times). That will show you how good the short circuit protection is. You will find that some of the systems that claim they have short cirucit protection haaaavvvve it but still burn up.









I have created probably more than 100 short circuit while working on my layout, or on my test tracks (all coinicidently of course), and my system is still standing









If the track does not short circuit trip on a portion of track it might indicate poor power connection also on that section.

Every year in the spring I check my track using a Tech HO Power pack rated at 2 amps, they have a limit around 2 amps with short circuit protection. Next before connecting to the track I set the power to Full and with a DVM set to DC Current 10 amps I put the DVM probes across the Track terminals on the Power Pack,and take a reading of the maximum short circuit current and write this down. (Ie 2.16 amps).


Now connect the Tech power supply to the track as a power source and go to several sections of track with the DVM and place the probes across the rails. You should read close to the initial reading of the power source. If it is slightly off then you are fine but if you see a major change then you have found a bad or weak electrical connection to that section of track. Keep doing this for the whole layout then you can go back to the weak sections and use the same shorting out method until you find how long the weak section is and you might find the problem at the same time.


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## Greg Elmassian (Jan 3, 2008)

Dennis in your test, are you measuring current? Specifically your 3rd paragraph. 

I built an 8 amp load, clip it to the rails and then measure voltage drops... I can spot a weak connection very easily and quickly. It does take some really nice big resistors to do this when you run about 24 volts, but it's really easy to detect the weak connections since the high current "amplifies" their effect.

Greg


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## Dennis Cherry (Feb 16, 2008)

Posted By Greg Elmassian on 21 May 2012 11:26 PM 
Dennis in your test, are you measuring current? Specifically your 3rd paragraph. 

I built an 8 amp load, clip it to the rails and then measure voltage drops... I can spot a weak connection very easily and quickly. It does take some really nice big resistors to do this when you run about 24 volts, but it's really easy to detect the weak connections since the high current "amplifies" their effect.

Greg 
I am measuring current in amps. Current is the flow of electrons which is what the motors need to move your engines. You can measure voltage but the actual load to measure is current.

It is easier to me finding bad connections using the current test then just measuring voltage drops.


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## Greg Elmassian (Jan 3, 2008)

Got it Dennis.... Degrees in physics, computer science, minored in electrical engineering. Gotcha on current flow, physics in high school.

Just checking since you CAN measure the voltage drops at intermediate locations easily if you have a load "at the far end" of the circuit. 

(maybe you did not understand, I measure voltage drops on each side of a rail joint, not across the tracks) 


I just touch my probes on either side of a rail joint. I can also measure the "local voltage" across the rails too, but this works for me. 


To me, quite a bit easier on the meter probes, with the sparking of connecting what is essentially a short circuit when checking current. 

I know you are only using 2 amps, so not so much, but I found it much easier to locate a problem (i.e. larger "meter" variation) with a heavier load. 

Not impuning your method, I guess I run heavier loads in general. 

Nice side effect of DCC: under load, a poor connection "sings" from the AC wave. 

Greg


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## Dennis Cherry (Feb 16, 2008)

Posted By Greg Elmassian on 22 May 2012 07:36 AM 
Got it Dennis.... Degrees in physics, computer science, minored in electrical engineering. Gotcha on current flow, physics in high school.

Just checking since you CAN measure the voltage drops at intermediate locations easily if you have a load "at the far end" of the circuit. 

(maybe you did not understand, I measure voltage drops on each side of a rail joint, not across the tracks) 


I just touch my probes on either side of a rail joint. I can also measure the "local voltage" across the rails too, but this works for me. 


To me, quite a bit easier on the meter probes, with the sparking of connecting what is essentially a short circuit when checking current. 

I know you are only using 2 amps, so not so much, but I found it much easier to locate a problem (i.e. larger "meter" variation) with a heavier load. 

Not impuning your method, I guess I run heavier loads in general. 

Nice side effect of DCC: under load, a poor connection "sings" from the AC wave. 

Greg Very true, your systems works also. 

The lighter load will tell you volumes about the rail joint condition also. just using lower amperage to do it. Hate to burn up a 10 or 20 amp power source, it is easier replacing a $30.00 HO supply if the short circuit device fails.


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## Greg Elmassian (Jan 3, 2008)

Yep, agree... turns out my power source for DCC will put out 11 amps all day, and if it fails there, then it's no good to me anyway ha ha! (too many high current trains) 

I just found that the higher current is a greater "multiplier" for finding a poorly conducting joint... so the poor joint really "stuck out". 

As an aside, this lead me to not connect everything in a "circle" but independently fed blocks. It becomes apparent right away if there are any weak connections, i.e. the "2 paths of power to the same point" in a typical "loop" kind of masks problems until you have TWO weak joints. 

It does make me have to use heavier feeders, but I notice problems right away. 

Anyway, just some rambling thoughts on how I have done this in what is pretty much a high current environment. I also have stainless rail, which theoretically should need more feeders than brass, though I have not found that to be true from a practical perspective. 

Regards, Greg


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## JackM (Jul 29, 2008)

As an aside, this lead me to not connect everything in a "circle" but independently fed blocks. It becomes apparent right away if there are any weak connections, i.e. the "2 paths of power to the same point" in a typical "loop" kind of masks problems until you have TWO weak joints. 

It does make me have to use heavier feeders, but I notice problems right away. 

Greg - I'm glad you mentioned that. It'll be fairly simple for me to split my layout between the yard and the loop out to the front of the house (the other loop is a reversing section), instead of the reversing loop and everything else. As you said, it should make problem-solving easier. 

Occasionally, MLS is worth its weight in gold. 

JackM


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## Axel Tillmann (Jan 10, 2008)

That's why I actually advocate to have only 1 connection to the track. If you are re-feeding, you may mask problems until you are totally lost









What I described in my test, is a 4 feet piece of test track, and short circuit that, no resistor just a straight screw driver







This test is designed to separate the good from the bad. The little red box thingy dies on first attempt


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## Dennis Cherry (Feb 16, 2008)

Posted By Greg Elmassian on 22 May 2012 10:25 AM 

As an aside, this lead me to not connect everything in a "circle" but independently fed blocks. It becomes apparent right away if there are any weak connections, i.e. the "2 paths of power to the same point" in a typical "loop" kind of masks problems until you have TWO weak joints. 

It does make me have to use heavier feeders, but I notice problems right away. 




My last railroad was wired that way, finding 1 or more bad rail joints is easier to find. If everything is in one loop it is harder to find just one bad or weak rail joint.


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