Lost at Hello

[itsallaboutme]

I want a simple DC layout, and I bought a model railroad basic wiring book and I read all about the fundamentals of DC.
Chapter 2, already lost.
This book says tie the entire common (negative) track together, but isolate the positive sections so you can control the trains independently in separate blocks.
Does not compute. How can the whole layout have a single common rail? How can one rail always be negative through an entire layout? If I want a train to go the other direction, don't I flip a switch and reverse the polarity? Doesn't that mean negative becomes positive and positive becomes negative? If the common rail suddenly gets a positive charge how come that doesn't fry something?
Then the book says to connect all the negatives to a ground, they suggest a water pipe. That I think maybe I grasp, it's some kind of a relational thing between the two poles. But is that what you do at train shows, go around searching for a metal water pipe?
I want to do more than a single circle someday, so I hope somebody can explain. Thanks.

 

[weekendrailroader]

Okay, here's a diagram I made:

Brown lines = rails

Red squiggles= negative power wire

Black squiggles= positive power wire.

Grey lines- plastic rail joiners.

The box with the circle inside is the POWER PACK/ TRANSFORMER. You need to connect one wire each to both of the D.C. (Direct Current) knobs/screws. Do NOT attach to AC power, as this will fry your locomotives. Connect one wire to one rail. This will be your negative rail. You will always use metal rail joiners for this rail when adding more track.

Meanwhile, connect the other DC wire to a SELECTOR (represented in the diagram by the box with the rectangles inside). The selector will allow you to select which "blocks" receive power at any given moment, and which don't. Blocks are created by electrically isolating a section of the positive rail from other sections. You can either cut gaps in the positive rail, or you can use plastic rail joiners which will not transmit electricity. Run wires from the selector and connect them to the positive rail. You will need as many blocks as you have positive wires, and you will usually only need one wire running to each block (unless you have a very long track).

The locomotive will pick up electricity from the positive rail once the selector turns the block which the locomotive is in on. The locomotive will use the electricity, and return the positive charge to the negative rail.

Hope this helps.
http://www.modelrailroadforums.com/forum/attachment.php?attachmentid=18080&stc=1&d=1264815181

 

[Grant F]

dcc might be easier for you, the bachmann ez dcc set is very simple, just programming of the engines and allows you to run a few engines at once,

all the track is on the same circuit just positive and negative

 

[itsallaboutme]

Thanks, but that explains the power as long as none of the trains want to back up.
In order to make a locomotive go backwards don't I have to reverse polarity? How can you reverse polarity if one rail is always connected to the negative?

 

[Grant F]

the controller will control forward and reverse, you dont need to rewire the track

 

[itsallaboutme]

Thank you. So I connect one controller positive wire to one block positive rail on each block, each block must have its own controller.
Now, can I connect all the controller negatives to the common rail? And it will still be okay if I throw one of the controllers into reverse?

 

[Grant F]

if you go dcc you can use one controller for many trains and not have to worry about multiple controllers and multiple power blocks

 

[itsallaboutme]

Do I understand you correctly -- you think DCC is easier to understand than DC?
I was sort of under the impression it was graduate level.

 

[IronBeltKen]

Do I understand you correctly -- you think DCC is easier to understand than DC?
I was sort of under the impression it was graduate level.

Maybe, if you start out trying to install decoders into old locos where you have to isolate the motor [electrically] from the frame. Usually you can buy locos with decoders already in them but they'll cost ~double what you'd pay for a straight DC loco of the same model.

Wiring, OTOH, is much simpler. You won't have to spend a fortune on toggle switches to keep the power blocks separate.

 

[flyboy2610]

Thank you. So I connect one controller positive wire to one block positive rail on each block, each block must have its own controller.
Now, can I connect all the controller negatives to the common rail? And it will still be okay if I throw one of the controllers into reverse?

You will only have one controller, unless you will be running more than one train at a time. It will have two wires, the negative goes to the track(which will be the negative rail), and the positive will go to the block selector. From the block selector, a positive wire will run from each switch (not controller) on the block selector to the positive rail of each block of track.
Each block will be energized or de-energized by a switch on the block selector. You can have every block on your layout energized at the same time, and run them from one controller. Study the diagram carefully and you'll see what I mean. The controller will have a knob or lever, depending on brand. Neutral, or off, will be in the middle, and forward will be in one direction, reverse in the other. The controller will automatically change the track polarity, depending on the position of the knob, so you don't have to do anything there.
It's like the electrical wiring in your house. The power panel is like the controller, and the individual circuit breakers control the different circuits, or blocks, in your house. Each block is powered by a breaker, but all breakers get their power from the power panel. It's not a perfect analogy, but it may help you to see what it's all about.

 

[hamltnblue]

Hi itsallaboutme.
Welcome to the forums.
Lets start over.
What are you trying to do?
Size of layout, amount of trains running same time etc.
Your original post talked about ground going to water pipe etc. Drop that completely.
There are 2 main types of HO model rr control.
1. DC. This is what most people grew up with. It stands for direct current. One wire goes on the outside rail and the other goes on the inside rail. Just like a car battery. You increase the throttle and it increases the voltage to make the engine go faster. To go in reverse it's just like swapping the battery leads to make the engine run backwards.

2. DCC. Same basic wiring for most layouts. One lead on the outside rail and one on the inside rail. The difference is that the controller sends a digital (computer) signal along with the track voltage. inside the engine is a decoder which reads the signal and responds with things like turn light on and off, speed up, slow down, and many other things including sound if you have a sound decoder. Each engine has an address which usually corresponsds to the loco number. The nice thing is that you can control each loco individually including speed, sound, direction, lighting etc.

This time of year most model rr clubs have scheduled open houses. I suggest you visit one or 2 and ask questions while checking out what they have.
Any questoins ask away.

 

[itsallaboutme]

Hi.
Okay, starting over.
I have a 4'x6' board (that in a former life was an architectural diorama) I have three circles of N scale EZ track and I connected the circles with turnouts 1>2>3>1. I still have track and space to someday make a little yard. I have multiple controller/power supplies. I want to run more than one train at a time.
I started isolating the blocks (circles/turnouts) with plastic rail connectors when I realized that I would be creating an inch of dead space (correction -- overlap) on each of the turnouts, in the area between the frog on one side and the plastic rail connector on the other side.
That's why I'm asking, I thought maybe by using common rail I would avoid the problem of those short dead areas. I can understand block control, but I can't understand common rail. If you wire a track that way, how can you back up a train without all the other trains backing up?
Thanks.

 

[CSX Robert]

...How can one rail always be negative through an entire layout? If I want a train to go the other direction, don't I flip a switch and reverse the polarity? Doesn't that mean negative becomes positive and positive becomes negative? If the common rail suddenly gets a positive charge how come that doesn't fry something?..

Common rail wiring is hard for many new comers to understand. It is also hard to explain and most books do not explain it very well. I don't know if I can explain it any better, but I'll try. Anytime you are looking at something electrical, no single point is positive or negative unless measured relative to another point that has a common reference. This means that a single terminal on a power pack is neither positive nor negative by itself, but it becomes positive or negative when measured relative to the other terminal. Since the power packs are isolated from each (this is a result of the step down transformers), they do not have a common reference. Since they do not have a common reference, one terminal of one pack is neither positive nor negative relative to one terminal of another pack. You can hook these terminals together and they become the common reference. The common can be positive relative to the other terminal on one pack, but at the same time be negative relative to the other terminal on another pack.

 

[itsallaboutme]

Thanks, that's helpful. So it is relational. I don't have to connect to a water pipe, that's a relief. But I guess I have to hook these power supplies in series somehow. I think this book might help me with that, or maybe something on the internet. I was struggling with that positive and negative concept.

I appreciate this resource, you folks are great.

 

[itsallaboutme]

Uh-oh. Now I am reading that common rail is not recommended for DCC(?)
I'm waffling now because I may want to upgrade to DCC someday.
If I wire in blocks, what do you recommend for that inch on the turnout piece that is live on one rail and dead on the other? Should I cut the track on the live side exactly opposite the frog? Or should I wire around the frog on the dead side and put insulators at the next rail section?
Or should I not worry about compatability with DCC and go with common rail?
Thanks.

 

[Selector]

Seriously...no...really seriously...you want to start in DCC. All you'll need are a power supply (if not included in the DCC set), the DCC system, and some wires. Heavier wires for a short bus to get the voltage largely whole out to the extremes of your rail system's major axis, and then a few pairs of thinner gauge feeder wires up to, and soldered to, the individual rails. That's it.

No blocks.

No need.

The decoders run the engines, just like little engineers, but you get to tell them what you want the engine to do.

In DC, in the same contiguous length of powered rail, what one engine does in directional motion, the other must also do...placed reversed on the track or facing the same way as another engine...makes no never mind...they'll both run the same direction unless you switch polarity manually.

In DCC, you don't switch polarity...the decoder does that for you, and that is what makes the engine reverse (and lights go on or off as you wish, and even sounds added if you have a sound decoder)....even in the very same contiguous length of powered track as another locomotive. In fact, unlike DC, you can make a DCC engine run into a parked DCC engine because you never told the parked engine to get out of the way!

Does that help?

DC = running the layout.

DCC = running the locomotive.

-Crandell

 

[itsallaboutme]

Crandell, you crack me up. It's easier to have a train wreck with DCC? I'm sold.

 

[Littlefoot14]

Did a re-railer come with your track? For the ime being it would make things alot quicker, especially cause you said you just re-started.

Looks like this.

Obviously you would want to upgrade it when you do scenery and track work. However ive been reading through this and im a bit confused with what you want help with, do you just want to learn to wire track or are you wiring track and are stuck?

 

[bkpigs]

Forget the Pos and Neg. for now

IAAM,

Forget about the positive and neg. Just remember it as the inside and outside rail. DO NOT cross them up. A DC motor does not care which side is Pos. or neg. It just wants a complete circuit. If the common rail happens to be "pos." when you switch directions it will not hurt anything. The blocked rail will then become "neg" and the train will only move when the "neg" side is completed. A good example is take a small light bulb (like out of a flashlight), two short pieces of wire, and a battery. Connect one terminal of the bulb to the Pos. Nothing happens. Take the same terminal and connect it to the Neg. Nothing happens. Now, connect one terminal to pos and the other to neg. It will light (granted that you have a decent match of battery and bulb). Switch the + and - and it will still light. A DC motor works the same, except when you switch the + and - it changes rotation.

The only time something can get fried is when both sides are + or you have a very high voltage.

Something good to look at is a household wiring book. While it is AC, the idea of source, load, then switch is covered. The three and be change to any order you want as long as your switch breaks the circuit (in this case your block selector).

Sorry for the long post but electric can be confusing and you will never learn everything about it.

 

[bigB]

As others have said, go DCC. Its easier and if you end up liking the hobby, youll want to do it eventually. Start slow and easy with like the Bachmann dcc installed products.

Have fun.