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MTH HO Engines- Power question and use on Digitrax/DCS

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  • Member since
    September 2013
  • 14 posts
MTH HO Engines- Power question and use on Digitrax/DCS
Posted by BrendanM on Friday, December 13, 2013 12:06 AM

Ok I have an odd question that I can’t figure out. I have recently come across a set of Alco MTH ho scale locomotives. Full sound/smoke/operating couplers. They have everything and run nice. When they run. I don't know if they are Proto sound 2.0 or 3.0. I'll check tomorrow as they're not my engines. 

This is the manual for them- http://www.mthtrains.com/sites/default/files/download/instruction/80dl18011i.pdf Again I don't know if they're Proto sound 2.0 or 3.0. I’m assuming this is the proper manual.

So here's my question- The manual says to NOT run these engines on AC power. Why!? Everyone says that you can safely run these engines on a Digitrax system. But they do not specify whether that system needs to be powered by AC or DC. My system is powered by AC. And most of the people I know that run DCC have it powered by AC of some sort. I don't know if there is really a standard, but is it safe to put them on the tracks when it’s AC?

When they run with a TIU, the TIU is powered by DC. But MTH TIU’s can be powered with AC according to the manual, but I assume this is for O gauge. But they don’t always run properly with the DC powered TIU…. They run fine one day and don’t run at all the next.

 

Random note--Is there a benefit to power Digitrax from AC or DC?

 

Please help! I'm almost completly lost regarding MTH products and DCS/TIU's.

Thanks!

Tags: dcs , Digitrax , MTH , TIU
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Friday, December 13, 2013 2:03 PM

 MTH seems to have little info on using DCS with HO, everything is directed to three rail O, where AC is the standard power source. The HO stuff is DC or DCC, they are not designed for AC< like all other HO (except Marklin).

My FAs run on my Digitrax system, and on the club's Digitrax. Only real problem I have is that they are hugely sensitive to dirty track, and the sounds cut out, and then you can;t restart the sound until you come to a stop. Plus with 2 units running ont he saem address, the sound will drop on one but the other keeps going, so when you stop and hit F3 to start the sound, the stopped one starts and the one that was runnign stops.

The power INPUT to the Digitrax booster works either way. AC or DC, it doesn't really matter - directly past the power input terminals is a bridge rectifier. With AC inpute, you don;t need any more than 15V to get full voltage out, because the rectifier and filter will give a peak output - 15VAC will actuall end up around 21 volts - for a 15V track voltage in the AC setting, you can use an even lower than 15V AC power supply. FOr DC though, you actualyl get a two diode drop (about 1.2V) so you need to feed it with close to 17V DC to get 15V at the rails. The old power supply they sold was a simple transformer, the one they sell now is more or less a universal laptop power supply, a switching power suppyl with DC output. Other manufacturers are doing the same - the laptop power supplies are universal input, 100-240VAC, 50-60HZ, so they work worldwide, plus they are common as dirt and thus cheap

             --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    December 2001
  • 1,932 posts
Posted by Stevert on Friday, December 13, 2013 3:37 PM

You seem to be confusing the power supply for the layout control system itself (DCC, DCS, etc), with what's actually supplied to the rails.  They aren't necessarily the same.

For example, you can power a Digitrax system with either AC or DC power (and to answer your other question, it really doesn't matter which, as long as it's within the range Digitrax specifies for the command station you're using.) 

But no matter which you power it with, that Digitrax system, all DCC systems actually, will put a square-wave AC signal on the rails.  The command station/booster do all the conversions and so forth internally, so what you end up with, other than still being "electricity", bears little resemblence to what went into it.  That's just how DCC works.

However, that "square wave" part is what separates DCC track power from "true" AC current.  They aren't the same, and can't be used interchangeably.  So saying that a DCS loco shouldn't be run on AC *isn't* the same as saying it shouldn't be run on DCC.

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