2-Rail Power and Control for a Beginner

2 rail generally uses variable DC voltage with polarity determining direction in conventional operation. For remote/command control, generally a fixed DC voltage is used with DCC. When going from 3 rail to 2, reverse loop/block wiring is also thrown into the mix (as opposite rails would meet up and short out). The above is true for just about all gauges.

Talk about poking a stick into a yellow-jackets' nest! My personal preference is straight DC (conventional). If I were to try some kind of command control, I would go with DCC. Lots of equipment available and best of all, it is not a proprietary system.

@bmoran4 posted:

2 rail generally uses variable DC voltage with polarity determining direction in conventional operation. For remote/command control, generally a fixed DC voltage is used with DCC. When going from 3 rail to 2, reverse loop/block wiring is also thrown into the mix (as opposite rails would meet up and short out). The above is true for just about all gauges.

So, would a DigiTrax system work for O Scale 2-Rail? I have one for HO.

Hi,

I use NCE DCC 10 amp system and it has worked reliably for 17 years on a 24'x26' layout. Most 0 scalers I know use NCE DCC.

If you want to run DCS on 2 rail, there have been a few threads about that lately on this forum.

Starting fresh, seriously consider dead rail battery R/C.  You may want to check out the Dead Rail forum.

From basic to full function features, your choice.

No wires, no polarity issues, no frog powering issues, TTs no issue, return loops no issue, no shorting issues, no issue with dirty rails.

That is the future.  Hopefully the very near future, although I have been predicting dead rail Lionel as imminent for two decades, and so far have been wrong.

I use a Variac, a step-down transformer, a Radio Shack brifge rectifier, several switches and circuit breakers, and two meters.  Under $20 last time I did one, but all the surplus shops went away.  Haven't checked eBay yet for transformers.

@bob2 posted:

I use a Variac, a step-down transformer, a Radio Shack brifge rectifier, several switches and circuit breakers, and two meters.  Under $20 last time I did one, but all the surplus shops went away. 

You've mentioned this setup before; maybe you can post a picture?

Mark in Oregon

Your Digitrax system will work fine just as it did for you in HO with the following proviso:  O scale locomotives generally draw a higher amperage, so a Zephyr likely won't be enough but a 5 amp power supply should be okay to start.  Lots of locomotives running may require hopping up to 8 or 10 amps.  As with all forum advice, of course, your mileage may vary.

Some HO/N systems run on 15.4 VDC where as O seems to want 18V and G runs on 21V.  A 5amp powerpack should run an engine with a can motor, no problem, though Ive not tried running O scale DCC on 15V.

I'm using the ESU Cab Control and it came with a 7A switchable voltage powerpack which seems capable of running 2 O scale locos @18V.   Check the documentation of whatever system you have, some of them cannot handle more than the 15.4V HO powerpacks, and some will run the larger scale stuff.

@christopher N&W posted:

Hi,

I use NCE DCC 10 amp system and it has worked reliably for 17 years on a 24'x26' layout. Most 0 scalers I know use NCE DCC.

If you want to run DCS on 2 rail, there have been a few threads about that lately on this forum.

I also use the NCE 10 Amp system and I like it a lot but what Tom Dempsey said is true. If you can get a 5 amp or more power supply for your Digitrax system it should work fine. That is the beauty of NMRA standard protocol.

I use MTH's DCS on all my layouts for control. I have used DCC.

I would suggest stepping back and deciding what you want to accomplish before moving forward with any choices. Some have suggested in the past,  looking at what engines you wish to select. That may help determine what control system you chose. How many trains will be running, for how long, and how big will they be? Do you want to run with smoke?

Battery has come a long way. I look forward to brushless long running, low draw engines. I wouldn't think smoke draw will change much anytime soon.

I like big consists with smoke on, and unlimited running time, so track power was my choice years back. MTH released 2 rail RTR engines so that helped me decide. I already bought a few of their G scale engines by then.

Good point, Joe. It makes a difference if you will be running a small layout with single engines and shorter trains or a large layout with 2 track mainlines with doubleheaded engines and pushers on the end. Lights, sound and smoke all add to the mix.

Ralph, Maybe more info about what you'd like to accomplish would help narrow things down a bit.

Some really good input here. Thank you all for your help. Thinking through the details of locomotives and number of locos running makes a lot of sense. I'll have to give that some thought. I like running multiple trains and also appreciate sound and smoke systems on at least some locos. Not necessary on all. Having sufficient amps becomes critical.

Good question Ralph. I really appreciate the replies. I am thinking of converting my 3 rail to 2 rail. Not sure if this is the right thread, but is it difficult to convert MTH engines to 2 rail?

Thanks

Tom

I have an MTH 2-8-0 Consolidation that has 2-rail and 3-rail capability. Not sure how this is done as I am running it on 3-rail now.

Ralph,

The basic process for switching an MTH engine between 3-rail and 2-rail running is to flip a switch and to remove the middle rail power pickups.  Your biggest problem will be determining which 2-rail track your engine will run on; not all 2-rail track is the same.  Since you don't mention it, I would guess your engine ran well on 3-rail track; you might not be so lucky on 2-rail track.

Chuck

Thanks Chuck. I will look into this.

Tom

I use a Digitrax DCC system on my layout.    I currently have an 8 Super Chief (old) command station and 2 8 Amp boosters.    I don't need all that, I have run the lay out with just the command station and one 5 amp booster.

As for what system is most common in O scale, I think it depends on where you are and who you ask,   If Digitrax is the predominent system in your area, HO, NO, and O scalers will be using it.    If NCE is most common same goes.    Around here, NCE is most common the the east and north side of the city, and Digitrax on the west and south sides.   And there are some pockets of Lenz  users and also EasyDCC (CVP Products).    The best choice is something that other modelers in your area use, so you can get some help getting started.

Most newer O scale locos do not draw more than one amp.    However, old USH and MG brass and teh diecast stuff from 30-40  years ago, tend to draw 2-3 amps under load.     Getting a meter and testing the draw on a loco before  you install a decoder can give you good information.     that said a 5 amp system should be able to handle at least 2 and probably 3 newer locos simultaneously without any issues.

Remember with DCC, the signal is a standard, so ANY brand of decoder will work with any control system.    Within the control system however, you need to use throttles and command stations from the same manufacturer.

@HudsonORailRoader posted:

I have an MTH 2-8-0 Consolidation that has 2-rail and 3-rail capability. Not sure how this is done as I am running it on 3-rail now.

I assume what you have is the Hi-Rail version (item number ends in a -1)and not the Scale Wheel version (item number ends in a -2). The Hi-Rail version has typical wheels and flanges that are normally seen on a 3 rail locomotive while the Scale Wheels version has wheels and flanges that are typically seen on a 2 rail locomotive. Either version can run on either 2 rail or 3 rail track however as mentioned above there could be issues running the “-2” locomotive on 3 rail track and the “-1” locomotive on 2 rail track. It depends on the track but in my opinion for the best reliability I would stick with “-1” locomotives on 3 rail track and “-2” locomotives on 2 rail track. I am specifically talking about steam here.

If you do seriously get into 2 rail someday it may be possible to turn down the flanges on your locomotive so it will run more reliably on 2 rail track. At one time I believe Al from Millhouse River Turntables knew a guy who would turn down the flanges on a 3/2 engine. Of course once you make this modification there is no going back.

I did this video a long time ago. It illustrated to me how good the control was over the train. Running under DCS the engines all got along and nothing derailed crossing switches and stuff while being pulled and/or pushed. You could lightly grab the top of any engine while the train was running and all the others seemed to adjust any slack or the like. I was amazed.

A new poster recently posted that there were so many engines that they had it easy. That wasn't the point. The cars have small flanges and if any engine were out of sync, something would derail. The train stretched almost all around the whole layout. I guess you had to be there??

I think track power is still for me. I bet a good DCC system could do it too.

@Engineer-Joe posted:

I did this video a long time ago. It illustrated to me how good the control was over the train. Running under DCS the engines all got along and nothing derailed crossing switches and stuff while being pulled and/or pushed. You could lightly grab the top of any engine while the train was running and all the others seemed to adjust any slack or the like. I was amazed.

A new poster recently posted that there were so many engines that they had it easy. That wasn't the point. The cars have small flanges and if any engine were out of sync, something would derail. The train stretched almost all around the whole layout. I guess you had to be there??

I think track power is still for me. I bet a good DCC system could do it too.

Wow Joe.   Really some demonstration.     Were all the engines in a lashup ?

Nice long consist with those engines distributed throughout.

I agree with Tom Tee.  Battery is the way to go.

Check out BlueRail.  It is one board that can run on AC or DC track power or battery. 

You can buy any brand DCC sound decoder you want for sounds.

If you have MTH engines with a DCC switch, it's even easier.

No DCC equipment or controllers to buy.

Ron

@bmoran4 posted:

2 rail generally uses variable DC voltage with polarity determining direction in conventional operation. For remote/command control, generally a fixed DC voltage is used with DCC. When going from 3 rail to 2, reverse loop/block wiring is also thrown into the mix (as opposite rails would meet up and short out). The above is true for just about all gauges.

One thing I'd add if you're looking at using some earlier MTH Proto-2 2-rail engines is to use relay-style polarity reversing for reverse loops as Proto-2 engines are polarity sensitive with respect to the DCS signal. There had been a discussion on this forum years ago regarding using DCS in a 2-rail context. If you're starting from scratch, I'd recommend DCC for command control, but a relay-based polarity switching method is still a good idea in case you want to run conventional DC.

@Dallas Joseph posted:

Wow Joe.   Really some demonstration.     Were all the engines in a lashup ?

Nice long consist with those engines distributed throughout.

Yes, I built the consist (lash-up). I didn't use the all engine command if that's what you're asking.

If I had to start fresh I'd give battery power a closer look but my layout is already wired and runs great. With battery power all the wiring is done on the workbench. When I was pulling wire under the layout years ago I remember thinking I couldn't wait for it to be done.

Joe, I run two steam engines up front and one pushing on the end of 30-40 car trains with no problems in DCC. My engines of different configurations from different importers are programed to run at the same speed. This includes up and down 3 percent grades.

One thing that would concern me about DCS is slipping on the grades. To me it seems like the stripes would move very fast if slipping occurred on the grade and the reader would interpret that as the engine is moving faster? Then wouldn't the engine adjust for that increased speed of the slipping wheels and slow the engine down? That interpretation and response would not be a desirable one as far as I can see.

2 rail O scale is electrically identical to 2 rail in N or HO.    The amperage per loco will vary, but the rest is the same.   So the wealth of knowledge that local modelers have about control systems, decoders, programming etc is available and useful to a modeler in O scale 2 rail.    Keep that in mind if you decide to convert.   

Also the general modeling information will be useful.     Generally speaking, hobbyists in 2 rail, whatever scale, tend to be more model railroaders than collectors.     It is a different mindset that applies to repainting, kitbashing, laying  track and what to do with the stuff we buy.

@christopher N&W posted:

....One thing that would concern me about DCS is slipping on the grades. To me it seems like the stripes would move very fast if slipping occurred on the grade and the reader would interpret that as the engine is moving faster? Then wouldn't the engine adjust for that increased speed of the slipping wheels and slow the engine down? That interpretation and response would not be a desirable one as far as I can see.

I suppose it would. I have made a steamer slip, it was running on it's own. So I just add another engine with it. It's pretty amazing how well they work with no traction tires.

My O scale layout is mainly flat so I'm not totally sure on this.

I run steam and diesel consists outside on my G scale. Out there is about a 2% grade. I don't have any issues unless I underpower a large train and stall out on "the hill". Any slipping engine is helped by the others. If the whole train stalls it can be unnerving. I've melted tires off of engines out there.

I have a rule of my own where I add an engine to every 20 cars added in a train. I try and pull the cars by hand and get an idea of what the train will do. Some cars go (are) bad and add too much drag. They have to be cleaned and oiled up again. That didn't happen much but it alarmed me. So I took the heaviest USA Trains metal cars and added ball bearings to help with the grades. All problems went away.

@christopher N&W posted:

One thing that would concern me about DCS is slipping on the grades. To me it seems like the stripes would move very fast if slipping occurred on the grade and the reader would interpret that as the engine is moving faster? Then wouldn't the engine adjust for that increased speed of the slipping wheels and slow the engine down? That interpretation and response would not be a desirable one as far as I can see.

Very perceptive of you. I have had this happen in only one case: The MTH P5a's (either Box cab or modified) have a wierd drivetrain.

The locomotives have all three axles powered on a long rigid wheel base:  One vertical can motor powers one axle, the other vertical can motor powers the other two.  At the top of an uphill superelevated curve, invariably one set of drivers slips.  And the loco gets confused in the manner you described.  The locomotive does not stall, but does go through a hiccup. It does not matter which set of drivers is forward, or which motor has the tach timing tape.  It's not all that noticeable (In fact, you have actually seen it Chris!).    It has even been known to happen in three rail MTH P5a's with traction tires  (mine have been converted to 2 rail).

The design is basically dumb: The result of poor weight distribution, an unsprung rigid frame, wide axle spacing,  and, I am guessing, the marketing based insistence on using two motors. Even though they power three axles.  The fixes are not easy: sprung drivers,  regearing for one motor, and/or a cogged belt connecting the flywheels. All are complicated solutions.  The easy solution is what I do:  just consist two (or three) of them together.  Another is to raise the railhead at the offending spot, but that's a bit ugly

I have never had this happen with any other loco I own. If it did, I would add a second loco