# AC and DC interoperability?



## VinceL (Jan 3, 2008)

I have the LGB Genesis engines and have added the MTS decoders.   I am in the process of getting all of the USA Trains Amtrak passenger cars (have 4 of them so far...now waiting on backorders since April /DesktopModules/NTForums/themes/mls/emoticons/sad.gif).  I have no layout at this time (temporarily an apartment dweller while we build a house).


Given that USA Trains engines (as well as just about all other G gauge engines) run on DC, I'm sure the passenger cars expect to be running on DC.  But, the Genesis engines run on AC. 


My question is whether there is any circuitry (perhaps constant voltage for the lighting) in the passenger cars that would be damaged by running on AC.  I would love to double-head 2 of the Genesis engines pulling all of the USA passengers cars.


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## Greg Elmassian (Jan 3, 2008)

You need to check each car for compatibility.


Cars that just connect light bulbs to the rails will normally be fine.


Cars with voltage regulators will often be fine, since they will use a full wave bridge. On DC operation, a full wave bridge will be used to guarantee the polarity of the DC from the rails to the circuit.


If you run on AC, the bridge also converts the AC to the fixed DC polarity.


So, most times, you are fine, but you need to check, or hear from someone with the identical car that they have tried it, or better yet, looked at the circuitry.


As far as I remember, my USAT streamliners have bulbs, and no voltage regulators, but this is from memory only. They lit up fine on my DCC layout, which your MTS is basically the same.


Regards, Greg


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## imrnjr (Jan 2, 2008)

*Maybe I missed something here, but I was under the impression that all LGB "G" scale ran on DC, or if MTS a half wave AC....effectively DC.  Lionel O gauge and most if not all 3 rail O's are AC, but ....are you sure the Genny is AC???/DesktopModules/NTForums/themes/mls/emoticons/unsure.gif*


 


*Mark*


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## Dan Pierce (Jan 2, 2008)

All LGB engines run on DC.  When these units have MTS added, they still run on DC, not AC.


In simple terms, MTS is a DC modulated wave, similiar to DCC.


I have several MTS equipped engines and my layout is run by Aristo's 27 mhz trackside in linear mode. 


So, just add those USA cars to your LGB MTS engine and have fun running them.


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## VinceL (Jan 3, 2008)

Thanks for the replies.  But, I'm still confused.  The transformer that LGB recommends is their own 50111 AC transformer which according to the documentation puts out AC.  Does the MTS Central Station rectify this AC voltage?  Can you use a DC transformer and connect it to the MTS Central Station?


Sorry for the questions, but Large Scale is new to me.  I've been a 3-rail O Gauge railroader (Lionel, MTH, etc.) for years where everything is AC.


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## Greg Elmassian (Jan 3, 2008)

MTS and DCC are AC, the wave goes both positive and negative. It is not half wave..


Regards, Greg


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## TonyWalsham (Jan 2, 2008)

Greg,


As I understand it, the DCC signal/power supply on the track is actually Bi-Polar DC not AC.
Even though it behaves like AC it has a square wave form, not a rounded sine wave.


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## Dan Pierce (Jan 2, 2008)

Vincel, Yes, LGB does use an AC transformer to power their Electronics, but the output is not the sinewave AC that is from your power company. 

The MTS unit/s do rectify and then modulate the DC output to your track. It is the modulation that carries digital info to make the receiver respond to your commands.


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## Greg Elmassian (Jan 3, 2008)

Actually, AC is just alternating current, not only sine wave.  So AC is appropriate. Bipolar DC is also appropriate, but sort of conveys the wrong thing, since each "cycle" is symmetrical. It is really pulse width modulated AC with a square wave form. The modulations are the data.


Regards, Greg


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## Pete Thornton (Jan 2, 2008)

Vince, 

All this AC/DC/DCC/MTS wave discussion is interesting, bu the easy answer to your question is to check the Specifications. Your LGB transformer specs say it puts out AC - fine. Now get the MTS central station specs and see what it's input is supposed to be. 

There are dedicated electrical forums (below) that probably have other 'experts' who can provide more confusing answers.


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## Treeman (Jan 6, 2008)

You can input AC or DC to a LGB central station.


Mike


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## VinceL (Jan 3, 2008)

Thanks for all the replies.  I went back and c-a-r-e-f-u-l-l-y read the Central Station documentation.  And, I did see that it will accept either AC or DC input.


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