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Working block signals for a small DC layout

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  • Member since
    February 2020
  • 1 posts
Working block signals for a small DC layout
Posted by KiwiSPfan on Monday, February 17, 2020 2:52 AM

Kia ora fellow modelers,

Down here in New Zealand, I'm building a small DC layout recreating central California in the late 1950s, and want to set up an operating signal system that a) interlocks with turnout position b) shows red if the block ahead is assigned to another cab (remember this is DC). 

I have two DC controllers, with 12 blocks assigned by 3 Atlas 215 selectors.

I'm looking for suggestions on how I can interlock the signals with cab selection (so a train doesn't travel into a block assigned to another cab) as well as turnout position? I plan to use two aspect colour light signals.

Any help, much appreciated.

Thanks!

KiwiSPfan

Wellington

New Zealand.

  • Member since
    November 2015
  • 78 posts
Posted by ROCK MILW on Tuesday, February 18, 2020 10:16 AM

My layout is a DC, double-track mainline with a set of crossovers and siding/yard lead.  The mainline is bi-directionally signaled (Automatic Block Signals without tumbledown) with three-aspect color light signals.  Each main track is divided into 5 blocks.  The signals are automatically controlled by Dallee Trak-DT current detectors.  The power to each of the 10 blocks goes through the current detector for a specific block.  I used resistors and silver conductive paint to allow detection of the rolling stock.

As you can see in the link below, I created a CTC panel to control the turnouts and signals for the crossovers and the siding.  The signals controlling movement through the turnouts are two-arm (one signal head above the other).  For example, for a train to move through the crossover from track 1 to track 2, the turnout is operated via the CTC panel, then the signal is lined for the movement on the CTC panel.

For a train to move from track 1 to track 2, the aspect should be red over green. This means that I have to 'trick' the detectors into making all the upper aspects red on either side protecting the crossovers.  I do this by running the lower aspect signal green LED wire through the Dallee Trak-DT detectors for the crossover blocks.  The detectors therefore 'see' a train in the crossover blocks, and the upper aspects are therefore red.  This also automatically causes the signals one block away from the crossover on either side to be yellow.

Included in the link are the wiring diagrams I made to figure this out.

https://goo.gl/photos/3JVZWi6NgCkk9GNbA

My wife and I honeymooned in NZ in 2010, from Christchurch to Dunedin and over to Doubtful Sound.  It was wonderful.  We took both the TranzAlpine and Taieri Gorge Railways--incredible.  I enjoyed seeing the NZ locomotives and signals.

 

  • Member since
    July 2009
  • From: lavale, md
  • 4,678 posts
Posted by gregc on Wednesday, February 19, 2020 12:52 PM

this isn't about occupancy detection.  it's whether the two (adjacent) blocks are connected to the same cab thru an Atlas 215 selector

as on the other forum, i suggested that an isolated power supply  supply current thru an opto and resistor connected to the uncommon rail in the one block and the ground of the power supply to the uncommon rail in the next block could probably be used to detect that both blocks are connected to the same cab.  The opto output used to control the signal.

perhaps other have ideas

greg - Philadelphia & Reading / Reading

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Wednesday, February 19, 2020 8:56 PM

Welcome to the Model Railroader forums. Your first few posts are delayed by the moderators. This ends pretty quickly. Please stick around and join in the discussions.

.

I am doing something similar on my next layout.

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My signals will only be red/green. If the points are in the correct position, the signal will be green, and a relay will automatically select the correct cab.

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I believe I will only need two blocks that will need the cab selected on a toggle, all the rest will be done with the switch machines.

.

-Kevin

.

Living the dream.

  • Member since
    January 2009
  • From: Maryland
  • 12,897 posts
Posted by ATLANTIC CENTRAL on Friday, February 21, 2020 3:20 PM

The Advanced Cab Control system I designed and use does all that and more. It does however require pushbuttons and relays in place of the Atlas selectors.

If the OP is interested, he can send me a PM.

And like Kevin's plan, it uses turnout position to reduce the needed cab selectors.

Sheldon

    

  • Member since
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Friday, February 21, 2020 4:02 PM

I’m using an Arduino Mega to control my signals for 14 blocks of mainline.  I’m using IR optical detection for occupancy.  Any type of detection can provide the switched low to control the Arduino.  I went with a simple Truth Table to operate my three color signals.
 
 
 
I haven’t included turnout position to the system as of yet but all that requires is a ground or switched low to the Arduino that can be provided from the switch machines.
 
 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 

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