DCC...What?????

[LDBennett]

I bought a Bachmann HO Single Truck Birney "DCC ON-BOARD" Trolley to run on my little point to point layout. Since there was no DCC some fifty years ago, the last time I did an HO layout, I do not have a real handle on DCC. My little point to point layout is running non-DCC, just straight variable DC voltage to the rails from the small Bachmann Power Pak.

The instruction sheet shows a Dummy Plug and there was one in the box. The instructions show how to install it but does not say why or when. The trolley runs on the variable DC voltage track but am I damaging the DCC Decoder by not changing to the Dummy plug?

So what is the purpose of the Dummy plug and removal of the Decorder? Should I be replacing the Decoder with the Dummy plug for straight variable voltage DC operation?

Besides the fact that Bachmann is a German company, why are their instruction for their products written in poor English? Is our USA market for their products not large enough to give us USA customers a better translation job and more complete instructions?

LDBennett

[jward]

most decoders are dual mode. they work on dcc, but will also run on dc as well without damage. the electronics in the decoder use several volts of electricity, so using a decoder on dc results in much poorer speed control than if the decoder were not there. the dummy plug replaces the decoder and allows full dc control of the trolley or locomotive.

having been out of the hobby for some time, you may not be aware of how much locomotives have improved. in particular, most have better motors than even the top of the line stuff from as recently as 30 years ago. install the dummy plug. i think you'll be impressed by how well your trolley runs.

[wjstix]

If the trolley runs fine 'as is', I wouldn't bother to change anything. Unless otherwise noted in the instructions or box, you can expect any factory-installed decoder to be a two-way one, which will work on DC or DCC. DCC systems use AC on the track, and the decoder can detect which type of power it's getting. If it's DC, it just passed the DC signal thru to the motor.

If the engine has a lightboard, removing the lightboard and decoder will speed up the engine, since the lightboard gets DC power and routes it to the lights first, then after a certain power amt. is reached, gives power to the engine. This allows you to stop the engine and still have the lights on in DC. The decoder itself really doesn't use power (unless it's a sound decoder), and removing it won't really change anything in the way the engine runs.

Besides the fact that Bachmann is a German company, why are their instruction for their products written in poor English? Is our USA market for their products not large enough to give us USA customers a better translation job and more complete instructions?

Never heard that one before??

I could see it if you had assumed they were Chinese....

[jward]

If it's DC, it just passed the DC signal thru to the motor.

The decoder itself really doesn't use power (unless it's a sound decoder), and removing it won't really change anything in the way the engine runs.

a decoder has a bridge rectifier, among many other components, which it needs in order to convert ac to dc to run the motor.  the bridge rectifiers i am familiar with  use about 1.5 volts just by themselves. in practice, a decoder uses about 3 to 6 volts of the 12 volts available from a dc power source. that's half of your speed control right there.  decoeders DO use power even on dc, thus the provision of a dummy plug to replace the decoder.

[richg]

The logic on the decoder requires about 5 volts DC before anything begins to happen. The decoder circuits are not using up power, it is just the logic circuits have to wake up first.
You usually get lights and sound around that time. The logic circuits feed the motor the power so the motor cannot respond without the logic circuits operating. The motor gets PWM, not pure DC.

The power to the motor has to work against any resistance by the motor armature. gearing, weight of the loco, weight of the cars it is pulling, etc.

Many users have to turn the DC power pack up much more than with a identical loco with no decoder and only the adapter.

Read the below links and save them to Favorites. There is a learning curve for DCC. Some do not like to say that.
Try not to compare to DC operation. It doe not always work.. Do not assume with DCC. It will bite you.
http://tinyurl.com/7cpwuxc

Below is a block diagram of what a decoder looks like. The circuits for sound are not shown.

http://www.awrr.com/dccintro1.html

Remember, the circuits are not robbing power to the motor. They require about 5 volts DC to wake up.

Rich

[richg]

Remember, this is the digital age. Just about everything is controlled by digital circuits that usually require about 5 volts DC to wake up.

Rich

[LDBennett]

Thanks for the info. The articles look to be the key to understanding DCC. My Google searches did not reveal the design details.

By the way I am aware of the digital age. I started as a design engineer in aerospace when the first digital IC were being introduced in the 1960's. I worked as a digital design engineer for 30+ years before retiring. I saw the whole of the evolution and was deeply involved. One of my digital instruments went to Venus to help map it.

LDBennett

[CNE Runner]

LD - One thing to keep in mind is that DCC requires uninterrupted electrical power (especially if you are 'running' a sound decoder). Any interruption in electrical power (dirty track/wheels, breaks in continuity, poorly designed power routing turnouts, etc.) will result in the locomotive stopping and 'rebooting' before any further action is possible...this can be very annoying.

My layout has a crossing that will stall my GE 45 Ton locomotive unless it is sped up slightly (and even that technique isn't 100% effective). The Bachmann GE 45 Ton is dual mode; but because of the aforementioned electrical 'glitch' I choose to run it in DC. Changing that recalcitrant crossing would entail extensive surgery on trackage ('had I started with DCC, I would have installed a Peco Electrofrog crossing and a Digitrax AR-1 reversing module to handle the power feeds. Ah, hindsight.).

Getting started in DCC is really easy (much of the advanced procedures aren't). The Internet is filled with assistance. A good place to start is the Wiring for DCC website at http://www.wiringfordcc.com/ as the 'author' words things in a manner that is easy to understand.

In any case, good luck.
Ray

[LDBennett]

CNE Runner:

Thank you for the insight but currently all I am doing is a point to point layout (18 inches wide by 8 feet long) with a single track that breaks at one end to the main track and two storage tracks, one each for the two trolleys I have. The most complicated control I have besides the Circuitron auto reverse module and the time delay module train detectors (two intermediate stops that have an adjustable delay of the stop period along with auto reversing at the end of the main track) is a electrical manual switch to turn off the appropriate storage siding for the trolley not in use.

The bottom line is DCC is not in my future. My question was whether to remove the DCC controller in one of the trolleys and replace it with the provided dummy plug, which has been answered. I have now done that.

I stumbled back into this model railroading when I inadvertently ordered an HO trolley instead of the N gage one I wanted for my grandson's little layout. Rather than return it I decided to make this trolley layout and so far I've enjoyed it. I am past the planning stage, have made the table, have nailed down the track, and wired as much as I can until the Circuitron modules arrive. I have a bunch of scenery supplies ordered and have all the buildings I want to use including four I built and a handful of other buildings that I bought assembled that have super detailing and weathering.

Its all been fun so far. I wonder how many 70 year olds start a model railroad project after having been away for about 55 years? I also have to help my 11 year old grandson with his N gage layout as it got destroyed by the cat after a family move.

Thanks for the help.

LDBennett

[Doneldon]

LD-

You might decide to expand your layout and use DCC in the future. If so, you can avoid the rebooting problem mentioned by CNE by adding a capacitor to the trollies. However, you probably already know that from your work experience.

                                                                             -- D