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Digitraxx auto reverser

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Digitraxx auto reverser
Posted by CGW121 on Friday, September 25, 2015 4:41 PM

I have a couple places I would like to install auto reversers. In looking online at the directions it shows 4 wires but it is connected to a reversing loop. Neither place on my layout is a reversing loop like the directions show, one is a Y the other is off a bridge. In both places there are 2 places where  there is the potential for a short. I am using a DPDT toggle now but would like to use the auto reversers. 

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Posted by selector on Friday, September 25, 2015 8:44 PM

Generically, and if you are positive there is a location where a metal wheel across a gapped length of rail anywhere in your system is necessarily going to cause a conflict in phase/polarity, you must switch that polarity somehow.  Once you know you must do this switching, you must power one side of an auto reverser with two wires on its input posts, and the other posts are outputs for two feeders to an isolated length of track.  That's it.  Period.

DCC Specialties (is that what you meant...not Digitraxx?) makes the PSX series, or did many years ago when I got my AR.  They explain in detail what you must do, including cutting dual gaps at each extremity of the gapped length of track if your trains are going to be longer than what can be contained in any two gaps.  However, you power the inputs of the AR with feeders coming off the bus, or co-terminated on your base DCC unit's outputs.  On the other side of the AR's board are two more output terminals for feeders to anywhere in the isolated track whose polarity/phase you must control.

There will be other niggling adjustments you must make to the AR as you go, such as its reactivity, and I think it needs to be programmed with an address, but I don't remember after all these years...sorry.

Bottom line, if a guy with average intelligence (me) can put it all together and enjoy it for ten years, I'm sure you can. Cool

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Posted by CGW121 on Friday, September 25, 2015 8:49 PM

No I meant Digitrax, thats the system I have. And it just occured to me how to wire it.

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Posted by richhotrain on Saturday, September 26, 2015 5:03 AM

CGW121

I have a couple places I would like to install auto reversers. In looking online at the directions it shows 4 wires but it is connected to a reversing loop. Neither place on my layout is a reversing loop like the directions show, one is a Y the other is off a bridge. In both places there are 2 places where  there is the potential for a short. I am using a DPDT toggle now but would like to use the auto reversers. 

I have used several Digitrax AR-1 units on my layout.  They work successfully with all kinds of revesing sections, not just reverse loops.
 
The wiring is pretty straightforward.  Two wires connnect the input side of the AR-1 to the main bus wires.  Another two wires connect the output side of the AR-1 to the track in the reversing section.  
 
It does not matter how each pair of wires is connected to the AR-1.  The input side of the AR-1 are terminals 4 and 5.  The connecting wires from the main bus can be connected to terminals 4 and 5 or flipped and connected to terminals 5 and 4. The connecting wires from the reversing section can be connected to terminals 1 and 2 or flipped and connected to terminals 2 and 1.
 
Any and all wires from the reversing section must be connected to the output side of the AR-1.  No wires from the main bus can be directly connected to the reversing section.
 
The other consideration is gapping.  The reversing section must be completely isolated from the main layout.
 
So, if shorts continue to occur, something is wrong with the wiring or the placement of the gaps.
 
Hope this helps.
 
Rich

Alton Junction

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Posted by CGW121 on Saturday, September 26, 2015 7:11 AM

So it takes the place of the DPDT switch? Does train length matter?

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Posted by Anonymous on Saturday, September 26, 2015 7:37 AM

CGW121

So it takes the place of the DPDT switch? Does train length matter?

Yes it does.

That is a matter of contention.  I posed this question a while back. Until a recent rebuilding project, my club had a psx-ar controlling the entrance to a staging yard via a wye.  The reversing section was on one leg of the wye.  And the layout has operated at the amherst show in springfield for 10 years.  The revesing section is ~1.5ft long.   On my home layout I have a wye with a 2ft revesing section powered by an AR1.  Longer than the longest locomotive you own seems to be the minimum requirement.

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Posted by richhotrain on Saturday, September 26, 2015 8:07 AM

CGW121

So it takes the place of the DPDT switch? Does train length matter?

Yes, the auto-reverser replaces the DPDT switch.  The DPDT switch reverses polarity manually.  The auto-reverser reverses polarity automatically, without human intervention.
 
To ensure reliability, the reversing section should always be longer than the longest train.  Locomotives, lighted cars, and resistored wheels will all trip the auto-reverser.   Typically, metal wheels on unlighted cars will also trip the auto-reverser.  So, if the train is longer than the reversing section, the auto-reverser becomes confused by mismatched polarities, as the train is simulataneously entering and exiting the reversing section.
 
Rich

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Posted by Anonymous on Saturday, September 26, 2015 8:34 AM

Idealy the train is shorter than an auto reversing section,  however this is not always possible.  In the situation with the wye, your train will most likely be longer than the reversing section, unless you are using the wye only for locomotives.  In any case the reversing section must be longer than your longest locomotive to prevent your locomotive from shorting out by touching both sides of the mismatch that required the installation of the reverser.   I would go so far as to say that a good rule of thumb for minimum length would be to have your reversing section longer than your longest consist as a minimum.  The PSX-AR and AR-1 are both good products and either should work for you.

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Posted by Anonymous on Saturday, September 26, 2015 8:57 AM

Here is a link to the previous conversation complete with explanations and other users.

http://cs.trains.com/mrr/f/744/t/229859.aspx

Note: we shortened our staging yard this year so the entire thing will fit in a Mini van.  this necesitated eliminating the wye.  As of the 2015 Amherst show it was still operating. 

 

Edit:  I hate using my iphone for making posts.   It will not make a hyperlink.

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Posted by CGW121 on Saturday, September 26, 2015 10:18 AM

Thanks for the info.

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Posted by richhotrain on Saturday, September 26, 2015 10:33 AM

CGW121

Thanks for the info.

 

So, did you get it working?

Is it a Digitrax AR-1?

Rich

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Posted by CGW121 on Saturday, September 26, 2015 12:12 PM

I need to buy it yet, but wanted to understand it first. I will get two of the AR-1s.

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Posted by richhotrain on Saturday, September 26, 2015 2:48 PM

CGW121

I need to buy it yet, but wanted to understand it first. I will get two of the AR-1s.

Be aware that the Digitrax AR-1 has a mechanical relay, so it reacts a bit slower than an auto-reverser with a solid state relay.  Normally, a mechanical relay will work just fine, but if you have other solid state components like circuit breakers on your layout, a solid state auto-reverser will work more reliably.
 
I had five AR-1s on my layout without any problems until I divided my layout into separate power districts, each protected with a solid state PSX circuit breaker.  Once I did that, the AR-1s couldn't keep up with the PSX units, so the circuit breakers tripped before the AR-1s could react.  So, I had to replace the AR-1s with PSX-AR units.
 
Rich

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Posted by Anonymous on Sunday, September 27, 2015 8:19 AM

You might consider the PSX-AR for the wye and an AR-1 for the other reversing section.  The solid state AR will probably work better in the case of reversing section limited by the length of the wye legs.  I have not tried to use them together on the same bus.  I will most likely be upgrading to the PSX-AR myself, as I plan to install CBs throughout the layout.

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Posted by jjdamnit on Sunday, September 27, 2015 11:39 AM

Hello All,

I went with the MRC AD520.

Once I installed it correctly I have had no problems on my Wye. This Wye is used to turn the USRA 0-6-0.

Don't let the MSRP fool you I picked one up for around $35.00.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by SouthPenn on Wednesday, September 30, 2015 2:00 PM

Digitrax Auto reversers and the 1940's relay they use, don't work well with multiple unit consist. I am removing my Digitrax Auto Reversers and replcing them with DCC Specialties PSX-AR Power Shield Auto Reverser / Circuit Breaker. There are a number of models of this auto reverser. I am installing the model that also changes the switch automaticaly and the polarity.

South Penn

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Posted by rrinker on Wednesday, September 30, 2015 9:31 PM

 Never had a problem using the AR-1. When properly adjusted they are as reliable as any. ANd a whole lot cheaper. There's nothing wrong with relays. In some ways they are MORE robust than solid state switches, especially when switching an inductive load (motors - like your trains). The only place they won't work is downstream of a non-adjustable device like the PSX breakers. But I've been using PM-42s and their relays because they give me Loconet feedback with no extra devices. ANd Despite deliberately loading a bunch of sound locos in one section, I had no problems with the inrush preventing the breaker from resetting when the short was removed. Some people claim they can't get a PM-42 to reset with as little as one sound loco - I say either it is adjusted wrong or the wiring is sub par. My plan is to avoid autoreversers altogether than just prevent the short. Swich machine contacts shouldn;t switch high loads if you want them to last, but adding a $5 relay accomplishes the reversing without waiting for the short.

              --Randy


Modeling the Reading Railroad in the 1950's

 

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

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Posted by richhotrain on Thursday, October 1, 2015 4:40 AM

rrinker

Never had a problem using the AR-1. When properly adjusted they are as reliable as any. ANd a whole lot cheaper. There's nothing wrong with relays. In some ways they are MORE robust than solid state switches, especially when switching an inductive load (motors - like your trains). The only place they won't work is downstream of a non-adjustable device like the PSX breakers.

That's where I encountered my first problem with the Digitrax AR-1 units. I had five of them on my layout, and they always worked well until I decided to create a series of power districts, each protected by a PSX circuit breaker. Once I did that, the AR-1 units never worked well because the solid state PSX units tripped first.  So, I had to replace the AR-1 units with PSX-AR units.

Rich

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Posted by SouthPenn on Sunday, October 4, 2015 2:07 PM

The Digitrax AR-1 must be manually adjusted and can be a pain. I always seem to have trouble going from single engine to 4 or 5 unit consist. I even had trouble going from a blue box Athearn to an new Atlas engine.

South Penn

South Penn

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