Still setting up my new DCC layout with a lot of help from this forum and have another question. I set up a siding as a Program Track and its connected to the Program Track output of my MRC Prodigy Advance and it works well. Is there any reason why I cannot also wire the same track to the main bus so I can use the siding as part of my operations as well as the Program Track?
You can’t wire it to the bus at the same time as it’s wired to the program track outputs.
What you can do, though, is wire it through a Double-Pole, Double-Throw (DPDT) toggle switch. The center lugs on the toggle switch go to the track, while the pairs on the ends go to the bus and the program track outputs.
I think Joe Fugate’s DCC tutorial diagrams this. He also adds some indicator lights, I think, to his circuit. I just wired up a toggle switch, and it works for me.
You can do that, assuming the siding is electrically isolated from the rest of your layout. I prefer something like that so I can program a decoder and then switch over to regular DCC and let the engine run and test out the new settings work without having to pick it up and move it back and forth between the layout and a programming track. You basically just need to wire up a DPDT switch so that you can choose whether that section is connected to the regular outputs or to the programming outputs.
My NCE cuts the power to the main bus when I go into loco programming. My sound units draw too much current to be programmed on the programming track, so I end up programming “on the main” instead.
What you are proposing is fine, but as has already been posted you can not have the program track wired to the program outputs and the main track power at the same time. To do so would very likely destroy some of the electronics in the program circuitry. Using a DPDT switch is one way to accomplish this. Run your loco under power into the siding, throw the DPDT over to program position, do your programming, switch back to main power and off you go. There is one big caveat.
Make absolutely certain that there is no possibility of having main power connect to the program track when in the program mode. Make sure that the program track is well gaped and insulated and that there is no chance for the rails to shift over time and re-touch each other. Also, be very careful about bridging the gap between the main power and the program track. For example, if one tender truck is on the main and another is on the program track you may create a situation where the current bridges through the rolling stock and damages the program circuit. As a result some modellers like to wire in a safety zone, a section of track between the main and the program that is isolated and completely un-powered when the program track is in use.
What you might want to strongly consider doing is having the switch that enables your programming track also deaden a buffer track on either end (if it is double ended), so that you can’t accidentally run onto the program track while it is in program mode. The Joe Fugate’s DCC clinic (search the forum for DCC clinic) has a diagram posted on how to do this.
I’d still wire the toggle switch in to connect either the program track terminals or the main track terminals to that track section.
NCE is I think the only system that does this. I know Digitrax and I’m pretty sure CVP allow you to program on the program track while others continue to run trains on the main uninterrupted.
–Randy
My Lenz system also cuts out the main when you switch to programming track mode. And, it also can’t program power-hungry sound engines on the programming track, and must use the main for that.
The problem with connecting your programming track to the main bus without a DPDT switch is that you will then be connecting the programming output to the bus, and hence to the rest of your layout. You may find yourself inadvertently programming every engine on the main while you think you’re only dealing with the one on the programming track. Or, you may be lucky and all those engines might draw too much current and make it impossible to program anything. Either way, it’s not the desired result.
The Prodigy Advance allows use of the programming track and still keeps the main active. If you have more than one throttle, you can operate on the main in “normal” fashion and program on the programming track with another throttle. If you just have one throttle, the main continues on with the present conditions while you program on the programming track.
I use a DPDT center off toggle switch to control one section of track in one of my yards for programming/operating. Some loco’s do need a programming track booster which can be left in line all of the time. I got the Power Pax; however, it is on my work bench system not the operating system.
OK there’s more info for a comparision chart. NCE and Lenz cut the main while programming, Digitrax, CVP, and Prodigy Advanced do not.
Yep, I was unaware of this. For a single user system, it probably isn’t a big issue but for a multiuser system, it could have limitations.
The great danger with Digitrax is that all the decoders on the mainline might respond to the re-program command.
It’s best to have a seperate program track away from the layout using a British Style Cassette to transport locomotives.
Back in the day we used to have these really “FAT” joiners that are all plastic and molded in white. Two for the rails meant that NOTHING gets into that section of track unless it was wired first.
Thanks everybody - If I had done my homework I would have found that this issue is addressed in Kalmbach’s DCC Made Easy book (which I have) on Page 28.
There is no difference in this regard between Digitrax and any other system. The Digitrax Super EMpire Builder, NCE PowerCab, and Prodigy Express all have only 1 set of output terminals and so send programming commands out the same wires that usually connect to the track. A switch to isolate a section of track as the program track is a must, otherwise you WILL program all locos on the track UNLESS you use Ops Mode or “Programmign on the main” which sends the program comamnds ONLY to a specific address (now if you have 3 or 4 locos with the same address…).
The Zephyr, Super CHief, Prodigy Advance, NCE Powerhouse, CVP, and Lenz systems all have two sets of output terminals., One for the main line, one for the program track. When programming, programmign commands ONLY go out the program track connections, NOT the track terminals, unless you are using Ops Mode programming, but again this is directed to a specific address. There is no danger of programming every loco on the track. The difference being that when programming with Lenz of NCE, all trains on the main will stop running if you use the program track. If you use Ops Mode, you can continue to run one loco while programming another.
–Randy