Signal Help

This forum is dedicated to Riding Scale Railroading with propulsion using other than steam (Hydraulics, diesel engines, gas engines, electric motors, hybrid etc.)

Moderators: Harold_V, WJH

Jerry_H
Posts: 189
Joined: Tue Feb 03, 2009 9:39 pm
Location: Central FL

Re: Signal Help

Post by Jerry_H » Sat Oct 29, 2016 8:44 pm

The Dino is right. This circuitry is a pain to work with.
I worked with the system on the Walt Disney World Railroad at the Magic Kingdom in Florida both as an electrician 44 years ago and as management 30 years ago. The blocks were not long for a narrow gauge (36 inches) railroad but were a PITA to get dialed in.
That said, it does work and has needed very little attention.

Jerry
www.chaski.com

User avatar
BigDumbDinosaur
Posts: 583
Joined: Tue Jun 28, 2011 9:19 pm
Location: Midwestern United States

Re: Signal Help

Post by BigDumbDinosaur » Sat Oct 29, 2016 9:33 pm

Jerry_H wrote:The Dino is right. This circuitry is a pain to work with.
It can be. The basis for contemporary practice was laid down in 1872 when William Robinson patented his failsafe track circuit and set up a company (which eventually was subsumed into Union Switch and Signal) to market his work. He, of course, didn't have access to the modern test gear we have while he was developing his signaling system, which means he was forced to work out the bugs the hard way using "by guess and by gosh" engineering. :D
Science makes it known. Engineering makes it work.

User avatar
Atkinson_Railroad
Posts: 158
Joined: Mon Jun 08, 2015 6:27 pm
Location: Michigan
Contact:

Re: Signal Help

Post by Atkinson_Railroad » Sat Oct 29, 2016 9:57 pm

Well, the subject of the thread title was, “Signal Help”.

The Original Post was asking for an idea on how to solve a track ballast resistance issue.

The “Miniature Railroader” in me was moved to reply with a solution to the problem with what was found
and authenticated a long time ago using a transistor relay driver circuit.
The parts used to achieve this objective can be, and will remain a multitude of choices.

Big Dumb Dino replied, “…In my opinion, that is not a suitable relay for use in block occupancy detection.”

I can only reply by saying… of course it’s not a suitable relay for block occupancy detection.
The relay(s) mentioned are [not] being used for block occupancy detection.
Referring to the URL posted earlier with this thread, a transistor [relay driver circuit] is what detects the shunted track condition.
Not the relay.

As for the comment about the circuitry being a "pain" to work with?

That doesn't speak to me coming from someone whom loves the avocation.

In the mean time, on to the next mile post.

John

southwestern737
Posts: 137
Joined: Sun Nov 12, 2006 8:45 am
Location: Magnolia, TX

Re: Signal Help

Post by southwestern737 » Mon Nov 07, 2016 7:29 pm

Thanks to everyone who replied both on the board and by PM, I learned a lot about signals and have put what I learned to use, time will tell but it looks like my signals are working much better.
Brent

User avatar
BigDumbDinosaur
Posts: 583
Joined: Tue Jun 28, 2011 9:19 pm
Location: Midwestern United States

Re: Signal Help

Post by BigDumbDinosaur » Tue Nov 08, 2016 12:29 am

southwestern737 wrote:Thanks to everyone who replied both on the board and by PM, I learned a lot about signals and have put what I learned to use, time will tell but it looks like my signals are working much better.
Brent
You're welcome.
Science makes it known. Engineering makes it work.

rkcarguy
Posts: 475
Joined: Tue Aug 22, 2017 10:33 am

Re: Signal Help

Post by rkcarguy » Tue Sep 26, 2017 3:27 pm

I'm resurrecting this old thread.
I was thinking of ways to deal with the same issue, that a poor connection with rusty wheels on steel rail would/could cause the relay to click in and out and a delay timer would likely fix it. This is less than $10 with adjustable time.

https://www.amazon.com/gp/product/B00VF ... _i=desktop

User avatar
BigDumbDinosaur
Posts: 583
Joined: Tue Jun 28, 2011 9:19 pm
Location: Midwestern United States

Re: Signal Help

Post by BigDumbDinosaur » Tue Sep 26, 2017 4:55 pm

rkcarguy wrote:I'm resurrecting this old thread.
I was thinking of ways to deal with the same issue, that a poor connection with rusty wheels on steel rail would/could cause the relay to click in and out and a delay timer would likely fix it. This is less than $10 with adjustable time.

https://www.amazon.com/gp/product/B00VF ... _i=desktop
You may be surprised to discover that steel-on-steel poses less a problem for ABS than steel wheels on aluminum rail. Iron oxide is electrically conductive to some extent, whereas aluminum oxide is not. More importantly, rust has a very weak bond with the base metal, so it immediately flakes off under the relatively high unit loading seen between the wheel tread and railhead. The result is rust will usually pose only a small problem with properly designed track circuits.

Delay-on-clear timing is generally more useful with aluminum rail, but is also of value in maintaining block occupancy through turnouts and diamonds. Generally, a time-out period of about one second is more than sufficient for uninterrupted blocks. Reasonably reliable detection in a turnout could require five to eight second delay-on-clear to minimize the chance of a false clear failure.
Science makes it known. Engineering makes it work.

rkcarguy
Posts: 475
Joined: Tue Aug 22, 2017 10:33 am

Re: Signal Help

Post by rkcarguy » Tue Sep 26, 2017 5:11 pm

Yeah I can see that. We get a lot of rain here and I could see my RR going a week or two without use if I'm busy, so I expect things to be pretty rusty at times.
That delayed relay in the link, its adjustable from ms to hours depending on how you jumper the board. I prefer to simply isolate the track correctly and run jumper wires so any dead spots are as small as possible, so when the signal says it's clear-it is. I'm thinking the trains wheel-sets will close the relay circuit, or if I must, I can wire in a separate relay that will be grounded across the wheel-sets to activate that one.

User avatar
BigDumbDinosaur
Posts: 583
Joined: Tue Jun 28, 2011 9:19 pm
Location: Midwestern United States

Re: Signal Help

Post by BigDumbDinosaur » Tue Sep 26, 2017 6:54 pm

rkcarguy wrote:I'm thinking the trains wheel-sets will close the relay circuit, or if I must, I can wire in a separate relay that will be grounded across the wheel-sets to activate that one.
You've got it backwards. Track circuits should be arranged so anything that shorts or interrupts the circuit results in a block occupied status. To do otherwise will make the track circuit vulnerable to a false clear and if more than one train is running, may set the stage for a cornfield meet.
Science makes it known. Engineering makes it work.

rkcarguy
Posts: 475
Joined: Tue Aug 22, 2017 10:33 am

Re: Signal Help

Post by rkcarguy » Wed Sep 27, 2017 1:02 am

I bought a 5 pack of relays that are a SPDT, so in the un-energized position one leg is closed, and energized the other leg is closed and the first one left open. I was going to have that power the red, so default = red. The train would complete the ground to the relay and close the other leg of the relay setting a green for the block it occupies, a red(again default so no action necessary) in the next block, and give a yellow aspect to the 2nd block away. Diodes would be used to prevent back-feed as needed. I think if I don't get too crazy with signals and just use one guarding each end of the RR heading towards the center, and the entries to the main and passing siding. I think I can do this with relays diodes and a switch on the turnouts indicating diverging route. Lets say I've got 5 blocks on the main plus one passing siding. Blocks 1 and 5 are either going to be reversing loops or dead ends. Entering into either block 2 or 4 will turn 1 or 5 to red(default). 3 will also turn red, or red over yellow(I'm wanting to use the single yellow searchlight halfway up on the mast for diverging route indicator like SP's cascade route) if the turnout is set to the siding. As I enter block 3 the green(main) or yellow(siding) will also trip the yellow at blocks 1 and 5. Easy enough when I'm the only one on the track. But how do I get the system to not light up a green and a yellow on the SAME signal, when I have a 2nd train on the RR? Could block 3's "detector" relay also "lockout" the green's from block 1 and 5 via 2nd relays on those signals?

I think as a rule because I'd be going downhill "light" and coming back up heavy with firewood, I'd want to have the uphill train take the main and the downhill train take the siding. Any passing would take place in block 3's siding and one would get visual confirmation of the passing of the other train in addition to the signals. If I wanted to add signals exiting block 3's main and siding, I think this would be easy enough.

rkcarguy
Posts: 475
Joined: Tue Aug 22, 2017 10:33 am

Re: Signal Help

Post by rkcarguy » Wed Oct 25, 2017 3:46 pm

I may have to hold on the detection side of the system until the track is actually in place. Being I'm 12" gage, and will be treating regular wood ties with an oil based product, I have no idea what the leakage across the rails will be when it's wet.

Soot n' Cinders
Posts: 658
Joined: Wed Jun 27, 2012 5:24 pm
Location: Marietta, Georgia

Re: Signal Help

Post by Soot n' Cinders » Wed Oct 25, 2017 6:27 pm

I don’t know about creosoted ties, but the ties on the 7.5” railroad I maintain signals for are pine that’s treated to below grade spec with the old CCA, copper chromium arsenic, treatment. I’ve done some tests for our crossing gate circuit and found only negiligible bleedover for a battery operated circuit. Even measured at around 1 inch on a switch. We normally don’t have issues with the gates false activating in the rain but during torrential downpours water will short across the rails and get them to activate.
-Tristan

Projects
-2.5" scale Class A 20 Ton Shay

Post Reply