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Turntable Pit Rail Wiring In DCC System, Neutral Vs. Hot

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  • Member since
    January 2005
  • From: Summit NJ
  • 308 posts
Turntable Pit Rail Wiring In DCC System, Neutral Vs. Hot
Posted by fkrall on Sunday, November 20, 2011 7:09 AM

I'm at sea with electrics, so please bear with my terminology.

I have a DCC system and am about to wire a turntable.  Does it matter which half of the pit rail I wire Neutral (black feeder) and which half I wire hot (red feeder)?  Logic (inexperience?) tells me "no," but I don't want to blow my system.

Similarly, should I coordinate how I wire the reversing sections through the auto-reverser in any way?

Thanks.

Rick Krall

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Sunday, November 20, 2011 8:30 AM

Which make and model turntable are you planning to use?  Some have the auto-reverse circuitry built in, and some do not.

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

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Sunday, November 20, 2011 9:13 AM

We need to know the brand and more specifics about the turntable.  A rather cheap Atlas turntable is already wired to automatically reverse the polarity of the bridge rails as it rotates beyond a certain point as explained in the instructions that come with it; other brands may not have this feature and DCC auto-reverse module such as a Digitrax AR1 will handle the polarity issue.

  • Member since
    January 2005
  • From: Summit NJ
  • 308 posts
Posted by fkrall on Sunday, November 20, 2011 9:56 AM

MisterBeasley

Which make and model turntable are you planning to use?  Some have the auto-reverse circuitry built in, and some do not.

Learn something every day...

It's a CMR turtable, which doesn't have auto-reversing circuitry.  The manual advises wiring the reversing sections ((2) 4" sections) to maintain continuity of power and sound.

Rick Krall

  • Member since
    January 2005
  • From: Summit NJ
  • 308 posts
Posted by fkrall on Sunday, November 20, 2011 9:57 AM

MisterBeasley

Which make and model turntable are you planning to use?  Some have the auto-reverse circuitry built in, and some do not.

Learn something every day...

It's a CMR turtable, which doesn't have auto-reversing circuitry.  The manual advises wiring the reversing sections ((2) 4" sections) to maintain continuity of power and sound.

Rick Krall

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Sunday, November 20, 2011 11:27 AM

Be advised, dcc on the rails does not have neutral or hot. it is AC, both are hot.

Rich

 

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    January 2005
  • From: Summit NJ
  • 308 posts
Posted by fkrall on Sunday, November 20, 2011 1:07 PM

richg1998

Be advised, dcc on the rails does not have neutral or hot. it is AC, both are hot.

Rich

 

Noted, Rich, thanks.  I was trying to distinguish between the red and black feeders.

In a nutshell, my question is this:  Does it matter which of the pit rails I feed with the red and which I feed with the black?  Same question for the reversing rails.  Unlike sections of the mainline or sidings, I'm guessing "no," but I want to be sure.

Rick Krall

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Sunday, November 20, 2011 5:22 PM

If you are planning to use an auto-reverser, then the answer is simple - it doesn't matter how you wire the turntable bridge rails.  The auto-reverser will handle it.  If you aren't going to use an auto-reverser, then you will need a double-pole, double-throw toggle switch to manually change the polarity as necessary.

I would try to wire the lead tracks from the main line the same as the stall tracks directly opposite them, if there are any.  This will allow you to run completely across the turntable with, for example, a consist with a dummy engine, or a steamer which is actually longer than the turntable bridge itself.

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

  • Member since
    January 2005
  • From: Summit NJ
  • 308 posts
Posted by fkrall on Sunday, November 20, 2011 5:59 PM

Exactly what I need, guys; thanks.

Rick Krall

  • Member since
    July 2011
  • 81 posts
Posted by CharlieM90 on Monday, November 21, 2011 8:48 AM

 

Good luck on the TT btw. I have a couple of the CMRs and love 'em. Easy to connect for reversing polarity (I use an AR-1 for mine).

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