3 Rail DCC O vs 2 Rail DCC O

@NW posted:

Are there any feature or functionality differences between the two?  I understand there are differences in DC.

Thanks!   

Nope. I have Digitrax DCC along with DCS and Legacy. I ran the wiring through a toggle switch to select between DCC and DCS/Legacy.

Joe Shipbaugh

The original poster asked an all DCC question; are there any differences between 3-rail and 2-rail DCC?  To answer this question, someone would have to be running both types of layouts.  I'm not sure how big that "pool" is, but I hope you get a decent answer.

Chuck

I have 2 rail DCC, my firend has a 3 rail layout with DCC.   there is no difference in functionality.

@prrjim, I'm curious; is your friend only running MTH engines with PS3 electronics?  If so, there may be no "functional" differences, but "feature-wise" he has a somewhat limited (less than the entire universe) pool of locomotives to run.  If your friend is running other 3-rail (non-PS3) MTH engines, Lionel engines, Atlas engines, etc., didn't he have to modify the engine electronics and/or motor to install DCC in those engines?

Chuck

I think the OP has to be clearer with the question. As it's asked, I too, think there's no difference.

How can the engine(s) know what rails they're on? (As long as they get power and signal)

I've been wrong plenty of times. So let's see how this one unfolds.

DCC has a wide open platform supported by dozens of vendors.  Not subject to any one company's solvency, availability,  limited sound files,  price gouging, service or longevity.

The only difference is how reverse loops and wye's are handled.  3-rail doesn't require any extra wiring, where as even with DCC, 2-rail requires an auto-reverse circuit or toggle switches to flip the phase of the DCC pulses.

Rusty

I do wish that ESU had created a Lok Sound 5L that supported two motors.

Some confusion may be due to my lack of knowledge on the subject.  I (perhaps incorrectly) used the "DCC" term to cover all digital systems and "DC" to pertain to analog systems.  I'll try to rephrase:

My understanding is that with analog (DC?) three rail, the outer rails are always the same polarity and the inner rail is always opposite in polarity.  This functionality facilitated the "toy" segment (whistle, uncoupling, etc.).

Since digital systems function with two rail layouts, does the center rail still offer any functional or feature advantages over two rail?

Hope this makes sense.

To That question,  I can't think of any other than the wiring issue for reverse loops. 

With 3 rail, one side of the circuit (AC or DC) is on the center rail and one side is on the outside rails.    You only need one outside rail for a complete circuit, so many modelers use the other for signaling and detection and whatnot

A Wells. I have ESU decoders in some of my two rail O both ver 4 and 5 are good for 8 amps. should be more than enough for any two motored O scale loco.

@Rick Rubino posted:

A Wells. I have ESU decoders in some of my two rail O both ver 4 and 5 are good for 8 amps. should be more than enough for any two motored O scale loco.

Rick - I assume you have the motors hooked up in parallel.  No issues at low speeds or other spurious problems then esp. during speed changes?  (Not particularly worried about the amperage output.)  Most full bridge ICs are adamant that you only connect one motor per channel, so that's where my concern comes in.  Anthony

I've got 24 Atlas locos with LokSound Version 4's & 5's (L's & XL's) with the motors wired in parallel. They run superbly at slow speeds (speed step 6 which translates to about 3 smph).

Some will buck or hesitate at speed steps < than 6 but putting a few cars behind them solves that. Others are smooth at speed step 2 or 3. This discrepancy is more a reflection of the cheap DC can motors than the decoder.

I have wired a couple of the ones with china drives in series to slow them down a bit. ESU also has a nice feature CV54 that sets up the motor to function with the decoder. in programing on the main you set CV54 to 0 then exit program on the main and hit F1, the loco will take off at full speed for a coupe of feet then stop. after that it will run much better , it will probably fix catnap's bucking problem on starting or stopping. Rick

@Rick Rubino posted:

I have wired a couple of the ones with china drives in series to slow them down a bit. ESU also has a nice feature CV54 that sets up the motor to function with the decoder. in programing on the main you set CV54 to 0 then exit program on the main and hit F1, the loco will take off at full speed for a coupe of feet then stop. after that it will run much better , it will probably fix catnap's bucking problem on starting or stopping. Rick

Since you two aren't having any detrimental issues, that does make me feel better about installing the LokSound 5L in two motor locomotives...should that come to pass.  I did see where some had issues when using the auto feature that you mention that it would set the maximum voltage CV too low and it was necessary to manually adjust.

Anthony

@A. Wells posted:

I do wish that ESU had created a Lok Sound 5L that supported two motors.

Like a few others have posted previously, I also have Loksound decoders in numerous makes and models of two motor engines (MTH, Atlas, Williams). All perform superbly.

My recent experience with wireless DCC sytems in OGauge was quite informative. Although DCC has basic standards, each manufacturer (there are many) has added some unique features to their product. Overall, there are a lot of very useful capabilities in the DCC system. The decoders I have tested had no problem handling two motors either in parallel or series. In overall capability, DCC is equivalent to any of the current OGauge track signal based systems.

@BOB WALKER posted:

My recent experience with wireless DCC sytems in OGauge was quite informative. Although DCC has basic standards, each manufacturer (there are many) has added some unique features to their product. Overall, there are a lot of very useful capabilities in the DCC system. The decoders I have tested had no problem handling two motors either in parallel or series. In overall capability, DCC is equivalent to any of the current OGauge track signal based systems.

Do you feel like one unique feature is getting more precedence over others?  There is one in particular that comes to mind.