First post here. Have a dogbone crossover for reversing. What is the best module [pricewise too] to achieve the auto reverse on a DC layout? A google search brings up a ton of info, mainly DCC. Unitrack.
Welcome to trainboard. Sorry, I don't know much about the DC auto-reversers, but someone will probably have an answer for you soon. :tb-wink:
I've used a couple of these, the Digitrax AR1 Digitrax.com: Digitrax AR1 Auto Reversing Controller I was new to DCC and similarly uncertain about how easy this would be. AR1 has been a doddle to configure and works very reliably. I've actually got some quite long sections supported by these modules to accomodate long train lengths. V pleased with how easy they are to set up.
Note that the AR1 (and all auto-reversers that I'm aware of) do NOT work for DC. That is because an AR unit reverses the polarity of the track that the loco is ON. This is transparent to DCC (the loco keeps going despite the change of polarity), but causes DC locos to reverse their direction of travel. A DC reverser would have to change the polarity of the track that the loco is about to enter to match that that the loco is currently on (i.e., flip the polarity of the main while the loco is in the loop). This is a more complicated problem to deal with automatically, and (IMHO) the reason many folks have avoided reverse loops with DC.
DC reversing loop DO you have a friend who knows electronics? The design of the circuit that I am about too describe is simple but requires a "head" who knows circuit design. There are two segments of track that connect to the track that is called the reversing loop. A DPDT manual switch can take care of this by simply connecting the tracks of the loop to the center poles; and the tracks of the lead-in sections to the opposing outside poles. There are solid state devices that function as a DPDT relay. This device could be triggered to "throw" the proper way by passing a electronic sensor. Or, you could leave it manual and make it a duty of the engineer to throw the switch. (that's what I did on my layout). I have a segment of track that is a cue to the operator to change the switch from its present setting to the other setting. This applies regardless of the direction of travel at the moment. Works fine, with no side effects. If he forgets the train stops. This could present a problem if left like this for any length of time. But, the real life trains have problems if the engineers don't pay attention so I guess this a prototypical problem, should it arise.
As far as I am aware (and I have been wrong before), there isn't any DC autoreverse module made. The reason is that the problem is a lot stickier in DC, since direction of travel matters, whereas in DCC all that matters is eliminating the short. The confiruation of the track, and how the cabs are wired will matter a lot more in DC, as well. It really is a much uglier problem.
If the idea is to have 'automatic running' on a simple layout (one main block with two reverse loops at each end?) then it is possible to do auto-reversing using latching relays and optical sensors. If it is any more complicated than that, it just isn't worth it. Do the reversing manually like almost any DC layout does, or go DCC.
