I'd like to add a reverse loop to my layout and have found online the MRC AD250 & Digitrax AR1 modules. Are they both equally good or does one have an advantage over the other?
Hi there, I am using a NCE Power Cab on my HO layout
,I have 3 tracks running, the layout is 10 foot by 4 foot, I have 3 tracks running and I have my locos going every which way. What do you mean by a reverse loop.
The AR1 is adjustable and not made by MRC. Those are two advantages.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Robbo6142 Hi there, I am using a NCE Power Cab on my HO layout ,I have 3 tracks running, the layout is 10 foot by 4 foot, I have 3 tracks running and I have my locos going every which way. What do you mean by a reverse loop.
The polarity of each rail must be consistently maintained across the layout. If the polarities are crossed, a short will occur, bringing things to a halt.
Depending upon the track configuration, the rails on two adjoining sections of track may not have matching polarities. For example, a section of track that loops back onto itself will have mismatched, or reversed, polarities. This is often referred to as a "reverse loop".
To avoid a short, the rails must be gapped at the point of reverse polarity, and a "reversing section" of track must be created by placing additional gaps in the rails further back from the point of reverse polarity.
By isolating, or gapping, a reversing section of track, the polarity of the rails within the reversing section may be flipped to match the polarity of the adjoining section of track, thereby preventing a short as the locomotive crosses the gaps.
Rich
Alton Junction
You will need an AR that can trip before the Power Cab can sense the short and shut down. There are only 3 on the market right now that can do that. The Digitrax AR1, The PSX - AR, And the Hex frog juicer. The AR1 and the PSX-AR will need to be adjusted. The Hex frog will not need adjustment but it is also not a breaker. If a short should happen on the gaps of the reverse section it will keep changing polarity until the Power Cab senses the short.
If your reverse section is long enough you can wire in a simple double pole double throw toggle switch.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
I have no experience with the Digitrax AR1, so can't comment.
I use several of the PSX-AR with my NCE system (5 amp Power pro with booster). Adjustment may or may not be needed is my experience, but it's a simple task if you follow the documentation. The PSX-AR is designed specifically to handle the high in-rush current associated with sound decoder equipped locos.
Mike Lehman
Urbana, IL
We have 4 PSX-AR modules on our HO scale club layout that is divided into 4 power districts using an NCE PowerHouse Pro 5 Amp Radio system with 3 boosters, and have never needed to adjust any of the PSX-ARs from their factory default values. Some members run 4 sound-equipped MU setups and sometimes there are 3 trains within one power district with no problems.
The Power Cab may be a different story with it's lower Amp output.
By default the PSX-AR is set at 3 amps from the manufacture. The Power cab trips at just under 2 amps. If you hook the PSX-AR to the Power Cab system then the Power Cabs breaker will trip before the reverser switches polarity. This is why the Power Cab needs an AR that trips around 1.5 amp or less.
As an aside I was told by another individual last night that the CVP Zoneshare is adjustable and would also work with the Power Cab. This is not confirmed by me yet but I will look at the CVP web site to confirm.
The PSX-AR can be set for a trip current range of 1.27 amps to 17.8 amps per the the DCC Specialties web site. The 'street price' is about $50.
The Digitrax AR-1 has a trip current range of about 1.0 amps to 6.0 amps(8 amp peak). The typical 'street price' is about $25.
Either if the above units will do the job with you NCE Power Cab system. I have an AR-1 that has been installed for over 13 years, and has yet to fail. Our club has AR-1's and the only issues were older BLI engines that have high 'in-rush' current. No matter how I adjusted the AR-1, a 3 unit consist of these engines sometimes would not trip the AR-1 all of the time, unless I max'ed out the 'pot' - Then the smaller non-sound engines would not reliably 'trip' the AR-1. This is really a QSI sound decoder issue and not the fault of the auto reverser itself. I suspect that even the high capacity PSX-AR would have issues with these 'pig' locomotives!
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
While the AR-1 can be set to switch at low enough current for the Power Cab, it may not switch the its output polarity fast enough to avoid the Power Cab sensing the short and shutting down anyway.
Whether or not this actually happens is also related to track wiring and other factors. For instance if the wiring and track has enough resistance and the AR-1 is adjusted to a lower trip current than the Power Cab, the Power Cab may never see the short, while the AR-1 does, and has plenty of time to switch the polarity without shutting down the Power Cab.
Solid state AR controllers such as the PSX-AR switch their output polarity much faster, and do not have this (potential) problem with the Power Cab.
Andy
Our club has the 5 amp MRC reverser but it does not work with the Power Cab. It does work with the 5 amp Power Pro, though.
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.
DCC Specialties makes both the adjustable PSX-AR ($50) and the non-adjustable OnGuard! OG-AR ($32). There's a blurb on the Tony's Train Exchange site that is called "PSX vs. OnGuard?" that gets into number of locos, etc. I have the NCE 5A PowerPro and split my moderate (small?) layout into 3 subdistricts with 2 OG-ARs and an OG-CB breaker for the mainline. I relied on Tony's advice as to what would work with my situation rather than trying to understand all the particulars early in my layout work and learning curve. I was very comfortable going with his advice and suggest a talk with him is well worth the time; you can seek to understand the options and technical aspects to any degree you like but if you want to be comfortable with your selections without understanding it all you might find a conversation with him very interesting and comforting in making decisions.
http://www.tonystrains.com/products/dccspecialties.htm
Paul
Modeling HO with a transition era UP bent