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Decoders do have a job to do depending on how those consists are created. In Basic Consisting all decoders are programmed with the same address. QUOTE Advance Consisting is a newer method and has added more flexible. It can also be the most confusing. This method uses the decoder to do all the work and the Command Station only sends out a single command for each operation. The key to Advance Consisting is CV-19. A decoder knows it is in a consist when the value in CV-19 is greater than zero. Advance consists use an address range of 1 to 127 (decimal). Some system only use 1 to 99. This is the same address range as used by 2 digit addressing. This can also cause a conflict if you have a locomotive on layout using the same 2 digit address as used by a consist. The consist address is stored in bits 0 to 6 of CV-19. Bit 7 is used for direction control of the locomotive while in the consist. Bit 7 has a "weight" of 128. If a consist address is 10 then a locomotive facing backward would have a value of (128 +10 =) 138 in CV-19. This is the way the decoder knows which direction to run when it receives a consist speed and direction command. Most systems will automatically add 128 to the address in CV-19 when a locomotive is reversed when you setup an Advanced Consist. If a locomotive is removed from a consist without changing CV-19 to 0, it will not respond to speed commands using the locomotives normal address, but the lights and sounds will work. (From Tony's Train Exchange)

BTW,

What has caused you to rethink using NCE or Digitrax? It would be interesting to see if your conclusions are valid or not.
 

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DCC and Points - can someone discuss
insulfrog, and Electrofrog and what the deal is with points on a DCC layout?

I am using atlas #4 switches (I'm in US), which may not be something you find in the UK, but I think that maybe the concept is universal on all track points.

Some of my locos, particularly the smaller ones with less electrical pickups (Percy!), stall over points. I am looking for the best way to work around this. I have been reading on the Hornby forums that they make these electrical clips for their points that power the frog - any opinions whether these would work on other brand points (my Atlas points, to be specific).

I found them for sale online here: http://www.modeltrains4u.co.uk/displayCate...clip&page=1
Click on "page 2" and they are about halfway down.

Also, if anyone has any info/photos about how these are applied to the layout, that would be especially useful!

Regards,
Jim C.
 

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Jim, Allan Gartner's "Wiring for DCC" website is the best place to start for information on how to wire points etc for DCC. I think he covers all you could wish to know and more..

David
 

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It certainly does that!

Thanks for the advice.

I took a quick look - more wiring knowledge than I have at the moment, but I have been diving in to this stuff head first for the past few months, with very little catastrophe (knocking on wood!). I will study his info carefully.

Best,

Jim C.
 

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DT
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Back EMF (electromotive force) is a voltage that is generated by the electric motor due to movement between the armature of the motor and the external magnetic field. Measuring this voltage allows you to very precisely measure motor speed and position.

QUOTE (http://www.acroname.com/robotics/info/articles/back-emf/back-emf.html)Typically a motor takes power in the form of voltage and current and converts the energy into mechanical energy in the form of rotation. With a generator, this process is simply reversed. A generator takes mechanical energy and converts it into both electrical energy with a voltage and current. Most motors can be generators by just spinning the motor and looking for a voltage/current on the motor windings.

When doing Back-EMF measurements for motion control, this fact that a motor can also be a generator is exploited. The motor is run almost continually as a motor with current being supplied to turn the windings. Occasionally, and for a very short period of time, the process is reversed. The windings are allowed to float and the inertia in the motor keeps it spinning while a measurement of the voltage from the spinning motor/generator is taken.

The voltage observed when the motor is spinning is directly proportional to the speed the motor is running. This fact can be used to "peek" at the motor's speed with no optical encoders or other forms of active feedback.

Normally a decoder just sends out a voltage to the motor and the loco moves accordingly. With Back EMF DCC, the decoder can determine the speed of the motor - that might be under strain as it goes up an incline, or going faster down the other side - and can adjust the output voltage in a way that keeps the loco going at a constant speed. Adding move voltage to the motor up the hill and reducing the voltage down the hill.

Back EMF does help the loco move at slow speeds too without stalling.

I've always found constant speed settings in model locos a bit strange as it is normal for any vehicle to struggle up a hill a little. Modern cruise controls in cars send more gas to the motor and perhaps down-shift to maintain speed up a hill, but old-fashioned steam engines never had cruise control and it looks good when the model slows to go up an incline.
 

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HI all, Ive just read all this jargon busting on these two pages and all I have to say is " my head hurts"
I'm sending my first DCC set back unopened, getting into bed, pulling the duvet over my head and staying there until DCC dies the death. How does a newby cope with all this gobbledey ****
?
Cheers ken (head hanging brain fried).
 

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QUOTE How does a newby cope with all this gobbledey ****

Don't try to read and understand it all at once - it's just not possible and for most people not necessary.

There are just two things you need to know to get started -

  • To run on DCC, a model loco needs to have a "chip"/"Decoder" in it to make sense of the signals being sent down the track
  • Unlike the old DC version of control, you can put two locos on the track next to each other and drive them away in opposite directions at the same time with just two wires attached to the track - no switches, no funny boxes attached to the track either.
When you've got used to that, other questions arise - like do I really only need two wires?

Anyway try those two thoughts, but don't stay under the duvet, you're missing something really good.

David
 

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QUOTE (dwb @ 26 Mar 2009, 22:29) <{POST_SNAPBACK}>Don't try to read and understand it all at once - it's just not possible and for most people not necessary.

There are just two things you need to know to get started -

  • To run on DCC, a model loco needs to have a "chip"/"Decoder" in it to make sense of the signals being sent down the track
  • Unlike the old DC version of control, you can put two locos on the track next to each other and drive them away in opposite directions at the same time with just two wires attached to the track - no switches, no funny boxes attached to the track either.
When you've got used to that, other questions arise - like do I really only need two wires?

Anyway try those two thoughts, but don't stay under the duvet, you're missing something really good.

David

Hi Ken,

Welcome to the forum


Follow David's advice here and take DCC one step at a time i did and now have absorbed more information as i've moved on in it and am still learning like all subjects in life its a learning curve ..... joining the forum here is one of the best things you could have done to find out more about DCC.

If your not sure about anything in DCC ask as often a link with pictures helps ...... members know about these links and have built them up as references.
 

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DT
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You definitely don't need to learn it all before you try it out, hey I used to test batteries by licking my finger, touching one end, then sticking my tongue on the other end. Now I know better. I learnt the hard way. Take it one step at a time - but don't lick the rails
 

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Hi Ken... I really sympathise. I see this problem of overload and well meaning info bluffing brains often in relation to DCC.

Perhaps the following will help - its a direct paste from my own catalog and the introduction I use for a DCC course I teach.

DCC really is easier than we all make it sound - its a thing best taken a step at a time, and like driving, from wondering if the clutch and accelerator will ever work together, one day very soon after you start learning, it simply becomes natural.... and never bothers you again.

(My 52 page catalog is available free to all MRF members - just PM me your snail mail address and we'll pop it in the post.)

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DOUG - Hope this is OK.. I added a couple of MRF references... if not, by all means change or delete... or add it to the Jargon buster area if you like.

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DEMYSTIFYING DCC

Seldom has a concept that was designed to simplify and improve the performance of something as simple as a model railway been so totally confused & complicated by misinformed marketers, overenthusiastic supporters and unnecessary new words!

We work with DCC every day, operate our own layouts with DCC and install for others, teach DCC subjects regularly, consult on DCC system design and troubleshoot for modellers with wiring problems, so we think we know it pretty well.

Forget the nonsense.

DCC is simple and it will transform the quality of running and operations on your layout. Read this page and we are sure you'll understand the basics&#8230; which are totally Jargon free - and be convinced!

So what's the big difference?

With DC control: pickups on the locomotive take power from the track directly to the motor.

The layout is divided into selectable or isolatable track sections and the controller is connected to individual sections of track as needed. Running multiple trains needs multiple controllers.

The locomotive will change speed and direction based on the controllers varying DC output voltage and the polarity of that section. All locos on the same section of track will react the same way, with no fixed direction relationship between forward and reverse as this is dependent on polarity.

Tuning a locomotives performance with a DC layout is almost impossible without changing gearboxes or motors. Any lights on locomotives or rolling stock will vary with voltage.

low speed means low voltage, and stalling is therefore common unless track is perfect.


With DCC control:
Each locomotive has a "decoder" installed (tiny - can be as small as your little finger nail). This decoder acts as a receiver for a digital signal created by the controller.

Because every locomotive can be given its own digital address (nothing more complicated than say the number on the side of its cab) and will only respond when it is specifically addressed by the controller, the whole layout can, at its simplest, be treated as a single section of track.

Each locomotive is able to operate independently and there is no unwanted interaction with others, so there is no operational need for separate controllers or isolated sections.

Because the controller provides full voltage at all times, loco and coach lighting is always constant, and the availability of higher track voltage means that starting and slow speed running are often significantly better than when the same locomotive runs on DC.

Tuning a loco and changing acceleration, starting performance, momentum and top speed, etc. with DCC can be accomplished by simply changing a few of the instructions given to the motor via the decoder settings.

This is simple to do with the DCC controller, and can be done separately for every locomotive. These "settings" are called configuration variables, or "CV"s, and are simply numbers entered by the keypad while the locomotive is in a special "programming mode".


They say I have to rewire my layout for DCC?

Well actually, you don't really. If the layout works well on DC, then it will work well on DCC too. There is a simple test for layout wiring that will remove all doubt and let you get going with a minimum of fuss. It is quick and easy and is called the "Coin test".

Simply disconnect all DC controllers and any other DC related stuff such as electronic track cleaners. Remove all locomotives and connect your DCC system. Turn on all sections and do the following.

Place the DCC control box where you can see the overload or short circuit protection light. Now take a coin and walk around the layout, short circuiting the track every metre / yard.

Watch the overload light&#8230; if it always goes off immediately, then the wiring is probably good enough. If it's a bit slow going off or hesitates, then mark that point and after you have finished the test, add another pair of power feed wires to that piece of track. That's it! Now you can start operating with DCC&#8230; easy wasn't it!


OK, but I (choose any) "Model in N": "Have older loco's I don't want to part with": "Can't afford to convert all my locomotives".

Size isn't an issue - We regularly fit decoders in tiny HO and OO locos and fit them to the smallest of N scale locos too. No problem:

Age isn't an issue - In fact every loco can be converted, and if you want help then a professional installer or Model Rail Forum can provide it. If you don't feel comfortable doing it yourself, then it can be done for you at a very reasonable cost!

Take your time:

Start by adding decoders to a few locos. You see, a loco with a decoder will work perfectly on normal DC, so you can get a few done early and be ready to operate as soon as you get the DCC control system (In fact, lighting often works better even on DC once a decoder is installed, and loco's often run better then too!).

I don't want to complicate my life with lots of new digital stuff - or computers on the railway - I just want to run trains!

Good, so do we; and we love DCC!

DCC can be as complex or simple as you want it to be, and you'll still get all the advantages that DCC offers: For example buy any DCC system & simply replace your existing controller - that means disconnecting two wires, and connecting them to the new controller. What can be simpler?

The difference is, with DCC you DO have choice.

With DC you must break the layout into electrical sections, you must have one controller per loco running and you have no choice but to run a large quantity of wire for even a small layout. With DCC, your layout can be a simple common electrical circuit if you want - or for the wiring enthusiast, the sky is the limit!

They say I only need two wires with DCC. Is that true?

Well&#8230; "Yes and No". At its simplest, you only have one common track circuit (called the power bus) and no section breaks are needed.
However as your layout grows, you do at least need to add "droppers" at regular intervals from the rails to the power "bus" wires. That means one common circuit with several points of electrical contact to the rails. Dead easy, but not quite "only two wires".

What's this nonsense about needing heavy wire - why should I use huge cable when even light wire was OK on my DC layout!

Well&#8230; actually no, it wasn't. You see the issue has nothing to do with voltage or current capacity - it's all about voltage drop.

If you take a long length of light wire, connect it to 12v and measure volts at the other end it will still read 12 volts. However, connect a load such as a car tail-light bulb & measure again - now its only 9 volts.. So what changed? The answer is the "load" of the bulb.

It's the same with DCC: However, whilst we can only run one loco at a time with DC, because we can run many locos on DCC we can also make a much heavier load on the wiring.

To make sure we don't have voltage drop, we use heavier wire. Simple, isn't it.

--------------------------------------------------------------------------------

Need more information? Just post your question on Model Rail Forum, call us on +61 8 9437 2470 or email us at [email protected] for a quick, honest, plain English answer!


Regards

Richard Johnson

(The information given above is reproduced directly from the DCCconcepts Pty Ltd catalog and may not be used or reproduced in any form other than specified above without specific written permission)



QUOTE (bypassm6 @ 27 Mar 2009, 04:16) <{POST_SNAPBACK}>HI all, Ive just read all this jargon busting on these two pages and all I have to say is " my head hurts"
I'm sending my first DCC set back unopened, getting into bed, pulling the duvet over my head and staying there until DCC dies the death. How does a newby cope with all this gobbledey ****
?
Cheers ken (head hanging brain fried).
 

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QUOTE (bypassm6 @ 27 Mar 2009, 08:16) <{POST_SNAPBACK}>HI all, Ive just read all this jargon busting on these two pages and all I have to say is " my head hurts"
I'm sending my first DCC set back unopened, getting into bed, pulling the duvet over my head and staying there until DCC dies the death. How does a newby cope with all this gobbledey ****
?
Cheers ken (head hanging brain fried).

DCC in its many forms has been around for over 20 years.

I think that it is here to stay.

John
 

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To dwb,and you other kind gentlemen,
Thankyou for the sound advice I will do what you say, I have my head above the duvet now and my head has stopped hurting
. Its good to be treated in the manner that you have treated my post and endears me more to this forum.
Sounds gushy but you know what I mean Ken
 
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