What is a relay??

[Anonymous]

Ive heard this term before, and i think you use this type of circuit to run many trains an on same track the old style, without any tmcc or dcs. how does it work, and how do you do it??

[FJ and G]

A relay is nothing more than a switch to control other switches.

dav

[Jim Duda]

Think of a "relay" as a simple toggle type switch. How do you control that switch? You toggle it with your hand, right? Now add a solenoid to it so when you energize the solenoid, it opens and closes the switch contacts. So you wire what ever you want to control through the relay contacts as if they were a regular switch and wire the solenoid to whatever you want to fire the relay...track sections, magnetic switches, pushbuttons on your control panel, etc.

Here is what the relay looks like that controls the crossing gate...

JD

[Big_Boy_4005]

Lets go a little further for our young friend Dave. A relay can be used to control things. It often consists of an electromagnetic coil, and a set of contacts. There are "solid state" relays, but let's not go there. The thing about realys that is really handy for us as model railroaders is, that they can be used to control things of different voltages.

Here's a real common use. Say you have a signal with a red and a green light, and you want to control it with an insulated rail on the track. The problem is the track can only give you an on and off action. But, by using a relay with the right contacts, you can switch the power from the green bulb to the red bulb when the train goes by. When there is no train, the relay's coil is relaxed. When the train is there, the coil is energized, and off with the green and on with the red.

The other nice part is that your voltage that runs the signal's lights, is totally seperated from the track.

Of course there are tons of other aplications for relays. [;)]

[FJ and G]

There are some snippets about train relays here (click into the several links provided):

http://www.scottsodds-n-ends.com/p1-relay.htm

I purchase my electronics hardware from Jameco, however, as they are a lot less expensive than hobby shops or Radio Shack.

DAV

[Big_Boy_4005]

Oh yeah Jerry, change the question on me.[;)]

The train control part is the next step in my signal example. Same coil, but now another set of contacts for the track power. The coil still does the same thing as before.

Jerry, I forget, how old are you again? I suppose I could look it back up in the old topic.[:)]

[Anonymous]

im 13.

--- for everybody else, i thought a relay was a thing that you would use to make insulated blocks to run 2 or more trains on one track. i guess not, so can anybody tell me in detail how to run two trains on a track, but simple enough thats so ill understand. diagrams would be usefull to me also. thanks[8D]

[lionelsoni]

There are lots of complicated ways to do it; but the simplest and oldest way is to divide the track (electrically) into several pieces, which are called "blocks". You do this by putting a plastic insulating pin in the center rail at the end of each block.

Next, you need either two separate transformers or one transformer with two controls that can act like two transformers. You wire the center rail of each block to the common terminal of an electrical switch, called an "SPDT", for "single-pole-double-throw". This switch can connect its common terminal to either of its other two terminals, according to which way the handle is pushed. Those other two terminals then go to the outputs of the two transformers, or to the two controlled outputs of the larger dual transformer. The other wire from each transformer, or the common wire of the larger transformer, goes to the outside rails.

You can install these SPDT switches on a panel with a diagram of the track, with each switch in the middle of its block. To run the trains, you switch the block that one train is in to one transformer and the block that the other train is in to the other transformer. As the train moves around the layout, switch the blocks ahead of the train so that the same transformer keeps on controlling the same train. This can get pretty exciting if you are running by yourself. It is exciting enough if you have one person running each train and just watching out for his own blocks.

You can also get SPDT switches with a center-off position, which can be handy if you want to leave something (like another locomotive) somewhere on the layout with the power off while you run the trains elsewhere.

[Big_Boy_4005]

Thanks for reminding me and telling everyone else how old you are. It is important so that we don't get too technical with you. I think this is a great subject for you to ask about. When I was your age I had no clue about this stuff. I hadn't even heard of a relay. I'm sure there are a lot of guys older than you that don't have a clue. By the way, I'm almost 43.

Yes, you can control more than one train using relays, but there is quite a bit more to it than just getting a couple of relays and bam it's done. There is a bunch of wiring, and some other things that we need to to understand to build a system. I have all kinds of diagrams that I can post or email.

Let's begin with an insulated track section. You are using 027 track right??

Here is an old Lionel diagram showing how to make a one, by prying up the tabs that hold one of the outside rails in place, and placing a non conductive material around the bottom of the rail where the ties are, and replacing the rail.

The easiest way to do this is by taking the insulators out of some rusty junk track, but you can also make your own. Look at the center rail to see what they should look like.

Don't forget the fiber pins in both ends of the newly insulated rail. (I almost did) You will need to remove the metal ones fron the tracks next to this one when you install it.



The relays will come, but we need some of this other stuff first. Beside, the insulated section is a basic concept. As a matter of fact my entire layout will be made up of hundreds of them. Let's stop here for now.[8D]

[Big_Boy_4005]

Thanks Bob that is a great explanation, and a much easier method than relays. I just happen to have a diagram handy, which I drew a while back for someone else.



Jerry, no matter which way you choose, you will need enough track on your layout for at least 3 blocks in order to run 2 trains. Actually dividing the track into blocks is one of the steps in the relay method as well.

The insulated track section is handy for other things too. you can use it to operate crossing gates, semephores, gateman, banjo signal, and a whole list of other accessories that need a simple on-off control.

[lionelsoni]

Elliot, quite a few lines are missing from your picture as seen on my computer. I don't know whether you can do anything about it.

By the way, from my point of view, you're not that old--closer to Jerry's age than to mine!

[Big_Boy_4005]

Sorry Bob, if you click on the images they will enlarge, and the lines will fill in.

I have learned over the past few months, that you and I are very similar. We both want to help people. The problem is that we have different styles, and when topics such as this come along we tend to see those styles clash a bit.

I like to try to get to know everyone here on the forum, and try to be friends with all. I feel that I know both you and Jerry fairly well, though you two may not know each other. I anticipated your finding this question, by asking Jerry his age. You saw that, and gave a very easy to understand resopnse.

I was not trying to belittle you Bob. On the contrary, I was trying to compliment you. I know that you are an electrical engineer, but sometimes that fact can work against you. Not from the perspective of knowing the material, there you truly ARE an expert. The trick is in communicating it in terms that laypeople can understand, which can sometimes be difficult for someone of high intelligence and education.

We mustn't assume too much prior knowledge from our audience, especially in a case like this where we know the person asking the question is young. Jerry started out asking about relays, and multi train control. We really have no idea what the specifics of Jerry's situation are, or if this was simply a rhetorical question.

So, with that said, let's set aside our differences, and focus on the task of helping our young friend figure out what the best way for HIM to run his trains is.

Sincerely,
Elliot

[lionelsoni]

Elliot, I certainly did not take offense at anything you posted and did not expect you to think that I thought you were belittling me. I suppose that you must have taken my comment about age as something other than the self-deprecation of my fossil status that I intended. If so, I regret it.

I really don't think that we have any differences to put aside. In particular, I like your picture and think that posting it can be very helpful to Jerry. I was just worried that he and others who could benefit would not be able to see it any better than I. But you have disposed of that worry for me.

[Big_Boy_4005]

No problem Bob!!! I have very thick skin.[swg] A simple misunderstanding. Things like that happen all the time in this medium. That's where the stupid smileys can be handy.[tup]

That is a quirk of posting line drawings made with MS paint. I'm trying to find out the best line width, and image size, and that was an old drawing. Another quirk is that I can't post a bmp type image, only jpg. I get around that problem by converting using an old photo editor, kind of sneaky.[;)]

I can't remember, have you posted any photos here?? It is a real handy trick to learn. If you ever want to have a diagram of something that you can't find out on the net, just ask, and I might be able to whip something up. It's kind of fun to take those images from the old Lionel manuals, and share them.

I also do photos of things. After the discussion on flanges I went out and found a diamond and took photos. What I discovered was very interesting. If there is ever a slow stretch, I'll grab that topic and we can revisit it. It may help explain derailment problems with some of our trains, and offer some possible solutions.

By the way, those white/yellow LED's were cool, I saved that link. Thanks!!