Connecting a dwarf signal to a Fastrack accessory track

You can't really do that with the accessory track, that's probably why you're confused.   For the dwarf signal, you need to add a SPDT relay so that you can alternately power the red and the green.  The relay coil will be switched from the insulated track, and the contacts have power going to the common, and the red on the normally open contacts and the green on the normally closed contacts.

You would have thunk Lionel would have created an accessory track with a relay shed (with a relay inside) just for this purpose of switching block lights.

You can use a relay as John said and make an outside insulated rail. Described here

http://www.jcstudiosinc.com/Bl...=410&categoryId=

Dale H

I suspected that, but I was hoping I wouldn't have to do that (getting under the table, but will have to anyway). My next question: What is the voltage for the relay and where is the best place to buy one. I live in a town that has nothing for guys like us.

Dale's the "relay man" here, but I'd probably just use a 12VDC relay with a separate power supply.

Here's the kind of relays I use, five for $8 shipped seems a reasonable price: http://www.ebay.com/itm/Signal...;hash=item1e6dd05cbd

These are DPDT, so you have two sets of contacts for other tasks.

I just ordered the relay switch, thanks. Okay...one more question. Since I can't use the accessory track for the dwarf signal, can I use it for crossing gates? If not, I'm sure I will eventually buy something it will operate.

Yes, the accessory track works for the gates.  Of course, you'll be using the track for the signal as well, you just need a relay too.

Gunrunnerjohn, Thanks for posting relay info. What type of diodes do I need to change AC to DC? Need 4?  How to wire?  What  # and where can I buy?   Art

Well, you really only need a single relay and a filter capacitor for a DC relay.  You can also use a bridge rectifier and a capacitor.  The capacitor is to prevent the relay chatter many DC relays won't properly function on unfiltered and rectified AC.

You'll want to supply this with something reasonably close to 12 volts DC, which is why I mentioned external power.  Just a simple 12V "wall wart" power supply will operate a number of those relays I referenced, and you can dispense with any diodes or capacitors.

Thanks Gunrunnerjohn, if the switch gets here this week. I'll install it on my next day off. In hindsight, I could have used my dremel to block my existing track since it is fastrack. Oh well...you live and learn. 

For Fastrack, you can remove the connection strips that join the outside tracks, then just cut a track at the start and end of the isolated track section.

If you cut Fastrack for isolation, check and make sure you leave at least two of the crimps under the track from the end so the rail isn't loose.  I like to smooth the edges fill the gap with JB-Weld so it's smooth as well.  Maybe not necessary, but it doesn't hurt.

My relays came in yesterday all the way from China. I didn't realize they would be so small. I'm going to have to buy a lighted magnifier that you can mount on you work bench so I can see what I doing when I wire it. I had one, but the arm broke.

Your arm or the magnifier?

Denny

The relay you purchased is PC mount and will work with low current applications. If you spend a bit more you can get relays with sockets and screw terminals. 

Dale H

Or look for one on the Internet.

Yes

As long as you get the terminals right. The relay linked has contacts with a 2 amp rating,OK for light switching.

Dale H

Great. Every answer I get brings a new question. This one is about crossing gates. Will I need a different type of DPDT relay for Crossing gates w/ lights?

NO, Just use a dpdt contact set.There is a diagram in my previous link for an MTH one. The Lionel is similar. 

Dale H

Just to let you guys know I have finally pulled together everything I need to do this project. I have to think about it for a couple of weeks before I start things.  I'll let you know how it turned out.

Okay this is absolutely insane. I have no idea what I'm doing. Dale I really appreciate your help, but I can't make heads or tails on what I suppose to do with the wiring. I see where to connect it to the relay, but I don't see how to connect it to the insulated track and transformer to make it work. I can live without signals.

The circuit shown in the diagram here works for me.  When metal wheel bridge the outside rails (one of which is insulated) the green light on the dwarf signal is extinguished and the red light is lit.

Ralph,

Is that a commercially available PC Board Assembly or a circuit you are assembling?

If available to purchase, how much and from whom?

I'd add a fuse to that circuit as well, right at the input from the accessory transformer.

Thanks Ralph, but I need a diagram for 'dummies'. I need to see where everything goes. That was my problem with other diagrams, I can see what needs to be done, but I need a blow by blow description.

There's really no point in building the circuit when all you need is the relay that Dale was suggesting.  It does the same function.

The relay circuit may be simpler to build and to understand, but to me this solid-state circuit is more fun.

The solid-state circuit is home-built from Radio-Shack components.

A "physical" diagram of the connections is shown below.

If you want to build it and need more help, you can also contact me directly at rlplatz@cox.net

/Ralph Platz

Dale, Gunrunnerjohn, I just want to let you know I finally got the relay wired and working. I used a test track to make sure I wired it correctly. Now I'm going to install it on the layout. Thank you for your help.

Ralph, I really appreciate your input, but I can't read schematics even though I know some of the symbols. Maybe one of these days I will try it your way.

The thing that was confusing me was the diagram I had was for a block. When I figured out what I had to do to make it a insulated section things fell into place. Ralph I now understand your diagrams better. Then I had to take a shovel and scrape my brains off the floor because my head exploded doing this project. My wife is glad I'm done too. She said I was a pain in the you-know-what trying to figure this out.

This?

It was a terrible thing to see as well!

Yuck!

Yep that was me. Chuck, if I had that diagram, I would have run down the street screaming then my head would have exploded. This is what I was using.

Denny, I am glad that you got the dwarf signal to operate with the simpler relay circuit.

The circuit which is shown in the diagram above seems confusing to me.  If I am reading it correctly, the U-C circuit from the transformer provides power to the bridge rectifier (whose DC output goes to the relay coil, #13, #14), but it does so only when train wheels contact the insulated outside rail at the top right of the diagram.  Wheel-contact here, therefore, turns the relay "On"; when no wheels are contacting the insulated outer rail, the relay is "Off".

The U-D circuit from the transformer provides power to the center rail for the locomotive and train, and it also provides power to the switching pole of the relay (#12), which in turn supplies power alternately to the red (#8) or green (#4) lamp.

There is also an insulated section of center rail, and this receives power only when the green light is "On".

I assume therefore that when a train passes in the direction shown in the lower right, upon contacting the outside insulated rail, it switches the signal from green to red and simultaneously cuts off center-rail power behind it, thus preventing any following train from moving forward. When wheels no longer contact the insulated outside rail, then the relay is turned off, the red light is turned off, the green light is turned on, and train-power is restored to the insulated center rail.

This design (for switching the insulated center rail off and on with the green light) works only for unidirectional travel in the direction specified.  If a train were to come from the opposite direction, it would contact the insulated outside rail first and shut off center-rail power in front of it -- a suicide circuit from which there would be no recovery.

Also note that whenever U-D train power is turned off (or interrupted), the power to the signal lights will also be turned off (or interrupted) -- both will go dark.

If that diagram is intended to use a DC relay, depending on the relay, it won't work as drawn.  I usually have to add a capacitor to smooth the DC for some smaller and faster acting relays.

A capacitor is almost always needed when a DC-coil relay is powered from half-wave DC.  But do you find this to be the case even when full-wave DC is applied to the relay?  And if so, is the capacitor needed only to reduce mechanical chattering, or is it also needed to hold the armature solidly?

Ralph

It is good practice to take out the ripple, with a capacitor, though the relay will work without it. Unlike an AC relay winding,the DC winding does not compensate for pulsed current. The pulsed current could put a small strain on the contact blades since they would move back and forth a bit,120 times per second if using a full bridge. Most likely with moderate use you could get away with out it.

If using a high value capacitor 4700 for example,you can also put a small value resistor (18 ohms for example) in series with one of the leads. This will reduce arcing on the train wheels which some people experience.

Dale H

Dale, that makes sense.  Thanks for clarifying it.

It depends on the relays.  Some of the faster acting relays will actually make and break on the 120hz from the bridge, others will only chatter, but still annoying.  Dale is right, a small value resistor is useful as well.  On a final note, if you're running DCS and powering the signal from track voltage, stick a 33uh choke in series with the power as well, the capacitor will attenuate the DCS signal if you don't.

That diagram is for blocked sections. What I did was run the wire from the #12 pin to the transformer like it shows, but I didn't run the wires to the third rail so the train will pass through without stopping. The whole thing is powered from the accessory side of my CW-80. Do you think the diagram is for post-war and MPC trains? The engine the guy was using in the DVD had a mechanical direction switch underneath. He also the trains had to be set for forward only.

The DVD I'm referring to is called 'Building An O Gauge Layout'. It's made by TM Books/ Video. It helped me build my table and all the wiring. A friend of mine who is a Lionel tech emailed me the diagram I posted. when I looked at it, I realized that it was the same diagram from the DVD.

Denny,

I am not sure that I understand your questions.  But here's a shot at it.

If you remove all the connections to the center rail that are shown in the diagram and apply power to the center rail independently of this relay circuit, then the relay circuit will control only the signal lights -- the signal lights will switch from green to red whenever the wheels contact the insulated outside rail, regardless of the direction in which the train is running.

And if the power to the relay and to its switching pole comes from an accessory tap on the transformer, then one of the signal lights will always be "On" -- even when center-rail train power is "Off" or interrupted.

If wired as described in the sentences above, this circuit will not stop any trains; it will let them all pass through, but it whill change the lights from green to red as they pass.  So this circuit will work (changing signal lights) with all 3-rail O-gauge trains: pre-war, post-war, MPC, and modern.


If, however, the circuit is wired exactly as shown in the diagram (such that it turns train power on/off at the insulated section of center rail), then it will work as intended only with locomotives operating under traditional transformer control, with their E-units set to forward and then disabled, and running in the specified directions.


/Ralph