I assume polarity controlling issues means (auto-reversing) and if that is the case the PM42 is fine, however if you have only 1 block/loop (etc.) that reverses I'd suggest an AR1(made by digitrax) as they are cheaper than a PM42 and easier to install. A PM42 can handle up to 4 blocks for auto reversing.
It can also do short suppression. which I have no working experience with so I'll not comment on that part
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The PM42 is old technology. You can do better. Our club (HO) is also using Digitrax, and we decided to use the NCE EB-1. It is solid state and the trip point is adjusted by jumpers. It is not an auto reverser, just a circuit breaker. We are having good luck with them under high loads.
For an auto reverser at home, I use the OGAR, which is also a circuit breaker.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
I model in N scale and I'll likely have four sound equipped (have two,planning on two more) steamers,the rest of my roster is steamers and diesels that are silent DCC equipped.The layout being pretty small (6X8) and designed to accomodate two simultaneous trains,there likely will never be more than three or four locos running at any time,most time two being maximum.
I plan on a minimal yard with individually switched tracks so that power is turned off when not required as I have a handful of DC locos that I'd like to let sit.Power draw will be light,however the size of the layout increases the frequency of polarity reversing,since loops won't be far apart.On the other hand,my operations will never compare to a club's,so I can expect reasonable life from the PM42,so I'll go this route.Thanks.
You didn't mention scale. One of the reported shortcomings of PM42's is their inability to recover from a short circuit when several or more sound decoders are sitting in the sub-district. I've only seen that with HO or larger scales. That's because of the larger capacitors that are usually installed with sound decoders. N scale (so far) doesn't have enough room for large caps.
The second reported shortcoming is that they can wear out because they use relays to cut power. Notice that they cut power with relays. They actually just sit there until a short is detected then the relay is energized and power is cut. So if they are wearing out, it's because they have seen a whole lot of short circuits.
We have 7 PM42's on our N Scale modular club layout. They vary in age between 4 and 6 years. All of them continue to function flawlessly. Some of our members can really give them a workout, btw.
Martin Myers
PM42's work fine on our modular club display layout, and I'm using one on my layout which is still under construction. I have yet to be convinced that the TOny's PSX products really are all that much better, at least when using a Digitrax system. PM42's really aren't suited to other systems since they can only be programmed via Loconet, usually a Digitrax throttle plugged right in to the board. But with a DIgitrax system, the PM42 has some useful stuff built-n that the others don't. If you set up a control panel using JMRI PanelPro, you cna have indicators for shorts in each of the sections. You can also make on/off switches that can cut power manually to any of the sections
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I'm actually designing my layout and I will have a few polarity controlling issues,so I'm wondering what would be the best option.I'll be using Digitrax DCC (DCS200 as main controller and an older generation DCS100 as booster) and I'm trying to figure out what I should really do.The PM42 is a cheaper option than separate polarity reversers but is it technically an "as good" option,or even better.I want the best reliability possible and am wondering what I should do.Thanks for any comment.