Block signal wiring

The transformer supplies HOT and RETURN. (some call it GROUND, which is not quite accurate, but for ease in understanding, we will call it GROUND.)  An energized track has HOT on the middle rail, and GROUND on both outer rails. If you insulate a section or two of outer rail on one side, it will become grounded only when a train goes by, by the action of the wheels bridging the two outer rails. It is this ground activation that we use to activate a simple (on-off) accessory, such as a gateman, or semaphore. The other terminal of the signal must have constant HOT connected to it, from the same transformer or another transformer that is in phase with the track supply transformer. The HOT waiting on the signal must use the same ground that the track supply uses.

In a simple example, using a traditional ZW transformer, you would use the A and U posts for the track supply, and you would use the B post, set at 14 volts, to activate the accessory. The track and the accessory both share a common ground return.

For a signal that has two "ON" states, such as a block signal like the 153, a relay performs the switching of the two ON states.

The relay at rest (no electricity to its coil) supplies power to the green lamp, through its normally-on contact, and when activated, switches power off the green lamp and switches power to the red lamp through its normally-off contact.

The insulated rail activates the coil of the relay, in the same way that it would activate a simple accessory.

The relay takes the place of the 153C contactor, which is a weight-activated device. It works OK, but using a relay is much more reliable and trouble-free.

As the train go past the insulated rail section, the relay coil returns to its normal (de-energized) condition, and the red lamp goes out, and the green lamp comes on.

This scheme has been discussed many times on this and other forums. It is described in a wiring schematic in the Lionel operator's manual, too.

Caleb,

Back in the day Lionel had a traditional way of illustrating block signal wiring using relays and insulated track sections.  It appeared in multiple yearly editions of a booklet entitled "How to Operate Lionel Trains and Accessories".  It shows the wiring for a single block and its signal, repeated 5 times in a row.  Consequently, it's fully functional for a layout oval with 5 blocks and signals.  Here's a look at the 1965 version; the block signal wiring for multiple blocks is shown on the bottom of Page 19:

In a previous post I colorized a copy of this to help folks sort out what were track sections, how many made up each block, where insulating pins are placed, and how the wiring was typically connected for each block.  Note the faint white letters on the green track sections.  The ends of what is drawn as a set of sections of straight track (labeled 'A' through 'T') actually wrap around to form an oval in real life (follow the letters):

Follow this link to my original post, capturing an additional lightly-detailed description:

      Block Wiring (12/1/21) | Mellow Hudson Mike

This may be a little overwhelming if you're a newbie but the colors may help sort it out.

Let us know if you get lost.

Mike

That diagram may be a little confusing at first, because it not only provides for controlling the block signals, but also turns on and off the track power as the signals go through their sequence. If you just want to get the signals operating, you can eliminate some of the wiring in that diagram.

I would suggest that you start by just installing one relay and one signal, on your work bench, and then go from there.

Perhaps I didn’t explain myself very well in my original post. I'm wanting to wire the block signal so that the light changes when the train rolls over an isolated common circuit i.e. the outer rail.

I already have the signal hooked up to a 153 IR sensor, but it is on a timer. I'm wanting the light to stay red for as long as a train is occupying the block past the signal.

You explained yourself perfectly.

The insulated rail and relay circuit that we described will do exactly what you want. Our suggestion does not use or need the 153 IR sensor. The fact that it uses a timer circuit means that it does not accurately tell you when the train has passed. It doesn't know the speed of the train, or the length. The relay method is simpler and more accurate.

Since the desired action is to change from one energized state (green lamp) to a second energized state (red lamp) you need to activate a relay when the train is in the insulated section. The track circuit operates the relay, and the relay contacts turn off the green lamp and turn on the red lamp. After the train has gone past the insulated section, the relay drops and the signal changes back to green.

Just one comment; if you want the signal to remain RED while any part of the block ahead is occupied, the "insulated" track section(s) would have to extend the whole length of the block.

Chuck

Or you could use two insulated sections, (and two relays) separated by a few regular sections. The method is called "operate and hold" followed by "release from hold."

The first section/relay locks up the circuit, and then when the last car of the train passes the end of the block, the second section/relay releases the first one, and holds the signal until the last car goes past.

You can do many things with relays. But there are some many variables on a toy train layout, that each application needs to be fine-tuned, taking into consideration the length of typical trains and the available length of the block.

It looks to me that the middle rail is what would be insulated in the photo.

While the middle rail may be "isolated" through the use of a fiber pin at each end to create a "block," every middle rail has to have power applied to it for trains to run, so can not be "insulated" in the sense I think you are using it.  In the case of "blocks," each block segment (separated by fiber pins) would have to have its own power connection to the middle rail in order for trains to run successfully from block-to-block.

On the other hand, when you insulate an outside rail with 2 fiber pins at each end of a segment, you are "breaking" only a short piece of the "common" connection which gets "bridged" back into the full common connection when a metal wheelset "bridges / connects" the outside rails as equipment passes through the "insulated" section.  That bridging / non-bridging is what causes accessory (block signal) activation.

Chuck

This older video from Lionel visually explains what's happening. (Hope I'm not violating something by posting, if so I apologize)

https://www.youtube.com/watch?v=DRE-W-0hUr4

@PRR1950 posted:

While the middle rail may be "isolated" through the use of a fiber pin at each end to create a "block," every middle rail has to have power applied to it for trains to run, so can not be "insulated" in the sense I think you are using it.  In the case of "blocks," each block segment (separated by fiber pins) would have to have its own power connection to the middle rail in order for trains to run successfully from block-to-block.

On the other hand, when you insulate an outside rail with 2 fiber pins at each end of a segment, you are "breaking" only a short piece of the "common" connection which gets "bridged" back into the full common connection when a metal wheelset "bridges / connects" the outside rails as equipment passes through the "insulated" section.  That bridging / non-bridging is what causes accessory (block signal) activation.

Chuck

Right, I understand. I just don't understand how you would connect it to a relay.

@LT1Poncho posted:

This older video from Lionel visually explains what's happening. (Hope I'm not violating something by posting, if so I apologize)

https://www.youtube.com/watch?v=DRE-W-0hUr4

Yeah I have seen that video. However it doesn't explain how to connect an accessory to a relay.

Might I suggest you look at this thread:

https://ogrforum.ogaugerr.com/...lay-not-with-an-itad

It focuses on using relays with insulated track sections to control signals and also provides specifications to purchase the selected type of relay you desire.  HOWEVER, after re-reading your first post, I don't know how well that info will work with FasTrack.  It should work the same way, but I'm no expert when it comes to FasTrack.

Chuck

If you would like some help in understanding the whole insulated rail - relay - accessory concept, please send me a private email message. I will respond with my telephone number.

info (at) SIBTA (dot) com

I used this diagram to wire my relays and signals/accessories.

This hideously ugly relay set-up does a perfect Job of "Catch and release" (LOL) as previously described above by Mr. Bloom. I have two blocks of Fastrack, each about 10 or so cars cars long. The lights will prioritize based on "who gets there first" and the other lamp is locked out. I believe that's what your'e asking about.  Just remember, though, I am only switching lamps. A head-on crash is still very plausible!

The relays are 18VAC and were cheap on eBay...if there's any left. I run a ZW, and I know there are times I have less than 18 volts, but they still pull in and don't chatter. I am using track power only to power the relays. For the lamps. I have a separate 12 VDC transformer.....like a battery minder. If the track power get's cut, (derailment for example)  the lamps will revert to the previous indication until track power is restored. Sorry I don't have a drawing. I just "did it", but I could make a drawing in a day or so. Basically, this is 18VAC switching 12VDC.

Here's a vid I made a couple weeks ago. Note the green light up on the wall. It is located at the south end of the bridge. The aspect will change at the same time as the one facing you once the train gets off the bridge. All with Fastback