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Simple Atlas turntable wiring with DCC

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  • Member since
    January, 2002
  • From: Loudonville, NY
  • 633 posts
Simple Atlas turntable wiring with DCC
Posted by Benjamin Maggi on Wednesday, January 10, 2018 4:01 PM

I am building a simple DCC layout and want to use the Atlas turntable, which has a split-rail ring design that automatically reverses polarity when it travels 180 degrees. I only need a few of the stall tracks, and I understand how they need to be wired up ("A" and "B" per Atlas' instructions). I would like to wire it as simply as possible.

Is it possible to wire up all the stall tracks and the turntable itself to a common DCC bus, and then after the turntable has rotated the engine use the DCC system (the handheld controller) to drive the engine off? 

I have seen wiring diagrams for DC single and dual cab control (don't use), and for situations where one transformer powers the train and the turntable motor (not happening here with DCC), and for wiring in kill switches to the stall tracks (which I might use), but all require a separate toggle switch to control engine direction

I want to avoid toggles or Atlas Twin switches for the engine direction control and just use the DCC controller. Is that possible?

Thanks.

Modeling the D&H in 1984: http://dandhcoloniemain.blogspot.com/

  • Member since
    February, 2002
  • From: Reading, PA
  • 24,879 posts
Posted by rrinker on Wednesday, January 10, 2018 4:58 PM

I always thought the Atlas turntable DIDN'T have split ring, but if that's what the instructions say - you need no extra switches or controllers or whatnot, just hook the DCC power to the track power connections and the split ring will take care of polarity flipping.

 The only reason those diagrams show a Twin used to reverse the train with one switch and the turntable with the other is because they are assuming the DC track output of the power pack is ALSO feeding the turntable motor. If you didn;t add the Twin as shown, the loco would move on the bridge at the same time thr bridge turned. And if you wanted the loco to head in but the table to turn clockwise - you'd throw the power pack direction switch and both the loco and bridge would change direction. By putting the Twin in as shown in the instructions, you can stop the loco independent of the bridge, and change loco or bridge direction independently.

 For DCC you don't need that, you can't run the turntable motor off DCC (well, you COULD install a decoder), so independent operation of the bridge is guaranteed. The DCC loco on the turntable can obviously be stopped and reversed at will with your DCC throttoel. ANd the spare power pack you use to runt he turntable motor is in no way connected to DCC, so it ONLY controls the turntable rotation.

                               --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    December, 2004
  • From: Bedford, MA, USA
  • 17,948 posts
Posted by MisterBeasley on Wednesday, January 10, 2018 9:00 PM

Yes, the Atlas does have a split ring and if you wire all the stall tracks per the markings, you will not need a toggle to control the locomotive direction.  DCC will work as desired.  No auto-reverser is required either.

I would recommend a simple SPST toggle for each stall track to shut off locos once they go to bed for the night.

It takes an iron man to play with a toy iron horse. 

  • Member since
    January, 2002
  • From: Loudonville, NY
  • 633 posts
Posted by Benjamin Maggi on Thursday, January 11, 2018 6:20 AM

That is what I thought, but thank you both for the confirmation. 

Modeling the D&H in 1984: http://dandhcoloniemain.blogspot.com/

  • Member since
    February, 2002
  • From: Mpls/St.Paul
  • 10,708 posts
Posted by wjstix on Thursday, January 11, 2018 8:37 AM

Just to confirm, the Atlas turntable does have the split design so it automatically reverses - the track opposite the crank / motor is dead as I recall, that's where the reverse happens.

One thing with the Atlas turntable is that you want to use as little power as possible for the turntable motor (assuming you're going to motorize it). A lot of folks connect the turntable motor directly to the straight 12V DC output of a power pack. That causes the turntable to be noisy and go very fast. Using something more like 4-6V will work a lot better.

Stix
  • Member since
    December, 2004
  • From: Bedford, MA, USA
  • 17,948 posts
Posted by MisterBeasley on Friday, January 12, 2018 2:01 PM

wjstix
Just to confirm, the Atlas turntable does have the split design so it automatically reverses - the track opposite the crank / motor is dead as I recall, that's where the reverse happens.

As I recall, there are no "dead" tracks.  There is a short spot between two of the stall tracks where the turntable track itself goes dead and comes back to life in the opposite polarity.

The turntable does not power the stall tracks.  Those must be powered individually and attention paid to wiring each stall track per the A and B track convention molded into the turntable base.

It takes an iron man to play with a toy iron horse. 

  • Member since
    February, 2004
  • From: Central Ohio
  • 425 posts
Posted by basementdweller on Thursday, January 18, 2018 8:06 PM

years ago I used a DC power pack controller to power the turntable motor, it was very noisy.

  • Member since
    December, 2004
  • From: Bedford, MA, USA
  • 17,948 posts
Posted by MisterBeasley on Saturday, January 20, 2018 1:39 PM

I still use an ancient DC power pack to drive my turntable.  Since I run DCC, I use one of the throttle outputs of the power pack to drive the turntable, giving me the ability to easily control the speed of the turntable motor.

I turned my Atlas TT into a pit turntable by mounting it below the layout base and installing a bridge on the deck.  This also put the motor inside a styrofoam pocket and reduced the noise.

Even with this and the lower voltage, it still is a very noisy accessory.

It takes an iron man to play with a toy iron horse. 

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