Comments on: Confusion With DCC

By: Graeme

Graeme — Wed, 06 Apr 2016 02:28:01 +0000

Hi Drew I run an oo scale layout which is in a u shape 17′ x 10′ x 17′ with a helix at both ends rising 15″ to another level of the same dimensions. The helix both run twin tracks. Altogether there is well over 300′ of track + a Walters 130 scaled foot powered dcc turntable with 7 twin engine sheds and I run 5 dmu s with lighted coaches and directional lights 4 diesel loco’s 3 steam engines and 1 shunter + take my building lights + signals from the same dcc unit which is an NEC powercab with 1 5amp booster. Never had a problem runs the whole layout from 2 power feeds.

By: Jean Alain

Jean Alain — Sat, 26 Mar 2016 01:09:25 +0000

Sorry for you guys, BUT, DCC is neither DC nor AC voltage. DC power is like the 12V battery in your car; it’s a steady 12 V. with lots of Amp. plus DC has no frequency. AC power is like the juice in our household outlets; it’s a Sine wave curve which oscillates at 50 or 60 Hertz depending on the country you live in. So, what is DCC then ?? DCC (Digital Command Control) is a Pulse width modulated square wave. The wave looks like the ‘0’ bit or ‘1’ bit in a computer. Square wave means the top and the bottom of the wave are flat. In the DCC world, the ‘1’ bit is faster in frequency than the ‘0’ bit. Hence the term Pulse width modulation or PWM. Most DCC system will run into the ultrasound range so we can not hear them. Don’t forget here that the audible range for human beings goes from 20 Hertz to 20 kHz.
For example, my NCE DCC command station runs at 31.5 kHz which is really out of the AC 60 Hz range.
As a summary: DC= 0 Hertz, AC= 50 or 60 Hertz and DCC= 20 Khz and above.
Now do we need a booster? If your layout is wired with 10 amp. wire gauge and if all the metal joints are thight enough to keep the best conductivity (= zero resistance) between each section of trackl then the booster is useless. Unless your main line exceeds 30 meters long. Run your trains first before buying a booster. You will then find out. Good luck Drew with your findings.

Jean Alain

By: David Woodruff

David Woodruff — Fri, 25 Mar 2016 17:07:00 +0000

Whom is considered the better restoration shops in re-paint, can motors, LED lighting, lettering, etc?.
I have several late 40s-early 50s loco/tender I would like restore,,d to good running condition to give my grand kids when I check out. I wish them to enjoy the trains without having to piddle with the old AF reversing units and other finicky stuff like headlamp, drooping boiler fronts, etc.
Thank You,
Best to all,
David Woodruff

By: Tom Hudspeth

Tom Hudspeth — Fri, 25 Mar 2016 07:38:54 +0000

In reply to Tom Adams. DCC is NOT AC, it is pulse modulated DC. You can not run AC engines on it. It has about 14VDC with command pulses added to represent 1's and 0's.

By: David

David — Thu, 24 Mar 2016 20:39:27 +0000

Good point Charlie. The KISS principle should always apply, and I do TRY to remember I was once a novice. Back to my post about bus wires and droppers – I hope I made myself understood – bus wires under the baseboard, droppers from the rails to the bus wires from each piece of track. Drew, don’t allow yourself too much grief in the DC/DCC debate. Get your system and connect it up according to the manufacturer’s instructions and run some locos. For a small layout it might just be the mythical 2 wires.

DCC is not so hard to understand if you are starting from scratch – it is a bit harder for old fossils like me who sometime mix my whites with my coloureds as it were.

By: William Kirk

William Kirk — Thu, 24 Mar 2016 19:30:02 +0000

In reply to Guillermo Patterson. A snubber circuit is simply a non polarized capacitor and a resister in series across the track. The size for HO should be 100-15-ohm 1w (recommend 2w or 5w, keeps it cooler), capacitor .1 - .47uF.

By: charlie di bella

charlie di bella — Thu, 24 Mar 2016 04:04:01 +0000

Just want to put my 2 bobs worth in, if i may.

Please Please Please , If anyone wants to reply via this post then when discussing things (anything) then please try and explain things in a simpler way.

Some of you may have years of experience and knowledge re railway, dc , dcc etc etc, but,,,
many of us do not understand your lingo and become very frustrated re explanations.

By: Guillermo Patterson

Guillermo Patterson — Thu, 24 Mar 2016 02:45:02 +0000

In reply to Banks. What ia a snubber circuit?. Explain it in plain words please. English is not my father lenguage. Thanks. Guillermo, from the Patagonia Argentina

By: Kevin Ching

Kevin Ching — Thu, 24 Mar 2016 01:54:33 +0000

Hi Drew
To understand how DCC works firstly you need to understand how a DC motor works. Briefly a DC motor or permanent magnet motor has one or two magnets acting as the field magnets around the outside of the motor the Armature is a series electro magnets that supply the magnet force to turn the armature the more voltage supplied to the armature the more magnetic power is generated to turn the armature faster. On DCC the main feed is AC power and the electronics that supply the motor with power to turn the armature of the DC motor convert the ac to dc in other words a small rectifier. the speed of the motor is supplied by increasing or decreasing that converted power through another or other part of that integrated circuit. now to control the variable power another part of the chip is fed via a digitally imposed signal on the ac power from the controller also this chip is programmable to an address that can be coded into the system so that it only picks up that signal that is intended for the operation of that particular loco or other device. To explain properly I would need to write a book. Now some do and can operate a DC loco on DCC but by not having the loco moving the spike voltage that is generated can and will burn out the DC motor over a period of time, this is why the motor has to be isolated from the ac and run via a decoder. Now all systems using power will incur a voltage drop depending on the distance from the controller, to over come this we use a booster pack placed at intervals around the layout to build this power back up to the optimum voltage again but the track has to be isolated from the first pack and so on. Usually three packs are sufficient for most medium layouts and the bigger the layout the more packs that will be supplied. you can also run a larger size track cable to offset this to a certain degree, However the more loco’s and other devices that you have running will drag more power or Amps from your system again increasing the voltage drop. In saying all that do not say I wont run DCC just because it sounds complicated learn as you go and I am sure you will never regret the decision and as with this or other system there is the added increase of costs. I converted from Dc to DCC a couple of years ago and have never regretted it.

By: Newman Atkinson

Newman Atkinson — Wed, 23 Mar 2016 21:28:46 +0000

Drew,
All is true. Don’t get tied up with AC power as you say. DCC is just DC with a constant power to the tracks and the control signals go out through the tracks with just a few volts higher than Standard DC. Like they said you only need boosters if you are running a lot of engines I have had 8 running on mine without boosters The constant power is to be able to send your signals to the engines and their chips at any time. There are some needs if wiring will go a long long way. and most of that is your throttle controller and the distance your cables for them go back to your DCC System to send the signal through your tracks. Any big distance in your track Buss Wires if there is power loss those long distance wires may need to be a heavier gauge like 16 or 14 gauge which will carry it farther. I have a 24 foot by 16 foot with wires to over 200 feet of track so far and I am only using 16 gauge trailer wire. My plan though is to link up some modules I had back in a club one time and they will be out in the second bay of the garage and I plan to feet that power with 14 gauge just in case. When I get my link bridge finished to connect the main layout to these module’s will give me a lot more layout when the guys come over for a lot more running room. Just think of DCC Power as DC with a twist. If it was really AC then I would not be able to try a DC engine on a DCC system to see how it would work , I don;t know about other systems but Digitrax will allow a DC engine be test run on the DCC system on a zero zero code even while running your DCC engines. (Caution though don’t run them to long under DCC and don’t let them sit on the track stopped under DCC as the voltage is still going to the engine even if it is stopped). It merely allows you to see how that engine might perform under DCC power. The Southern Pacific Cab forward running a test run in DCC. It was a very old DC engine but We did not leave it stopped on the track and we only took it around the layout a couple of times as with the extra few volts DCC has can overheat the motor of a standard DC engine if let sit on the track without a chip installed. Some MFG’s tell you on some of their engines that Not to run them at all on DCC without being converted to DCC. It could be the light circuit board or the wiring to the motor.But they will say that on the box. But most older engines can be tested on DCC as I just stated. I work with older engines and I test them to make sure it should perform well under DCC before I spend the money on the chip.
from Newman

By: Jim

Jim — Wed, 23 Mar 2016 21:11:04 +0000

In reply to Banks. Good point I knew that the bus wires should not form a complete loop. I completely missed the point that the track needed to be double gaped some place to prevent forming a complete loop in the DCC signal path.

By: Joel Dee

Joel Dee — Wed, 23 Mar 2016 13:04:57 +0000

Drew,
Wire the Controller and all the boosters. Wiring is the most difficult so do it all at once and not
piecemeal. Each controller and booster acts as its own
circuit breaker so all of the transformers must be identical to maintain even power. Place the
controller unit in a central location and the boosters, if wiring permits, are best spread around
as having them all together creates excessive heat and you will need a computer fan to cool
them. Wiring to the individual blocks will determine placement. Blocks should be separated
by use and NOT by track length or size of run. ei- use the boosters for yard power as the number of loks and decoders can be extreme. Next would be an area with heavy siding use for industries. Last would be the mains. Buy a RRampMeter V1 from amhobby.com which gives accurate track voltage and amp readings and is something you will need to find shorts and dirty track as time passes.
I don’t know the gauge on your layout, but use cheaper zipcord wire for the main track buss wires from each unit. This is known generally as cheap speaker wire at the box store and use 12 AWG or in the EU 4 or 6. Zipcord has low inductance, but I suggest three twists per foot or 10 per meter.
It is not solid core so one will need to use a series of terminal buss strips or terminal strips to distribute power to track feeders, etc. as soldering is out. Using terminal strips makes it easier to repair track power and to track-down shorts and there is no soldering or suitcase attachments to remove. These buss wires are very large, lose less power over distances, but you must take a solid copper wire and insert/solder/shrink wrap it into the ends to make smaller wire size connections to the controllers, boosters, and feeder terminal strips. Track Buss Wiring is the backbone of the entire system. and you have the boosters to do it right.