Best way to wire this layout

[Gary Pfeil]

OK, a few thoughts. I hadn't considered David's point about the short interuption caused when throwing the toggle being seen the same as dirty track and perhaps resetting a sound system. I have never used a toggle in that manner and it semed like it should work, but he has a point.

I hope you have better luck with the MRC reversers than I did, they worked ok most of teh time with diesels but often failed to switch polarity, resulting in a breaker trip, when I ran steam. I believe this was due to the pilot wheels not picking up power as all (newer) diesel wheels do. I got the same short when I closed the gap between the main block and the reverse block with a jumper wire. I gave mine away and replaced tehm with Tony's , which have been flawless.

I don't think a center off would have changed anything for the fellow whose loco stopped when polarity changed. That's just odd, as others have said.

You can certainly wire both a dc pack and your dcc to toggles and throw it to either, just don't cross a gap from one to the other by mistake.

The auto reversers don't work with analog locos. I wired two of my reverse loops as shown in the (very) crude sketch below. AR is for auto reverser. The two toggles are marked "digital/analog" and in/out. This is not for running dc, it is simply to allow an analog loco running on dcc to use the reverse block. I built it to allow visitors locos to run on the entire layout. It hasn't been used in years! I leave the first switch in digital, and never have to worry about using either of them unless I run an analog loco. When I want to do that, I switch the first toggle to analog, and the other to in (I only run in one direction but if you want to run in both, perhaps label them east/west) After the train is in the block, stop it, flip the toggle to out, and change direction on the throttle. Now you are ready to depart. My reverse loops are staging at either end of the layout, so all trains sit for a spell anyway so this doesn't bother me.

 

[60103]

What we found running Analog on DCC was that you ran the train into the reverse loop and the polarity switched to match up OK. When you reached the exit point, the polarity switched over, but the main line was still set to go into the loop. At this point we had to "reverse" the train, like running regular DC.
Does anyone know how brief an interruption will cause a chip to reset? And how long (or short) can the gap be when you change a DPDT switch?

 

[baldwinjl]

I think it depends on the decoder. I'll see if I can find a spec, but I think that I've read that all decoders are not created equal in this respect.

Jeff

 

[Pitchwife]

What we found running Analog on DCC was that you ran the train into the reverse loop and the polarity switched to match up OK. When you reached the exit point, the polarity switched over, but the main line was still set to go into the loop. At this point we had to "reverse" the train, like running regular DC.
Does anyone know how brief an interruption will cause a chip to reset? And how long (or short) can the gap be when you change a DPDT switch?

The way I handled a reverse loop was not to switch the polarity of the loop, but to switch the polarity of the mainline. This was on a closed, contiuous running line with a reverse loop on each end, so I don't know if it would work in your situation. Anyway, the loops were isolated from the mainline, and at any time after the engine entered the loop the mainline polarity was switched so that when the engine left the loop the mainline polarity was ready and waiting to keep the train moving in the right direction and without any interuptions. The switching could be either manual or automatic using a sensor. This was on a DC layout but could still work with DCC. I guess that the DCC reverse loop switcher would be on the mainline instead of the loop.

 

[baldwinjl]

OK, on the decoder resetting....
The time for the decoder to reset if it does not receive an update is programmed by CV11, and can be anything from disabled (never time out) to at least 20 seconds. BUT, if there's no power, it is only going to be as long as the decoder can stay up, which is going to be way less, but I don't see any requirement or specification. It will depend on whether the loco is moving ro not, what light are on, etc. This time most certainly varies from decoder to decoder. However, I think that a throw of a switch, with an open time of a few milliseconds is not a problem. If you have center off, and stop there, I think you are done, the engine sill stop, and then restart once it sees a message for it (which should be pretty quick). I don't think there is any case, unless the booster is shorted and stays shorted, where things shouldn't start up again, though.

On the reversing the mainline idea, it should work fine, but if you have more than 1 reversing section, and more than one is crossed at the same time, all bets are off. If you reverse the polarity of the loop (using a switch) while the train is in the loop, you will be fine when the train leaves the loop. BUT, when you enter the loop the next time you need to have the polarity set to match the side you enter from, so you'd have to keep track of that. With the price of autoreverse modules I think switches would get old fast.

With the analog operation on DCC it makes sense that you need to change the direction of the engine leaving the loop. The loco is seeing a dc offset on the DCC signal that is one rail relative to the other. The locomotive operation is just as if it was DC, but the autoreverser still works for keeping the track from shorting.

Jeff