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DCC Track voltage with a Fluke 77 rms meter

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  • Member since
    January 2005
  • From: Winnipeg Canada
  • 1,637 posts
DCC Track voltage with a Fluke 77 rms meter
Posted by Blind Bruce on Tuesday, August 21, 2012 3:11 PM

My NCE procab with radio, measures 13.28 VAC at the rails and at the command station. Is this value to be expected?

73

Bruce in the Peg

  • Member since
    October 2006
  • From: Western, MA
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Posted by richg1998 on Tuesday, August 21, 2012 3:25 PM

Sounds good. We measure 13.7 VAC with Harbor Freight inexpensive multimeters and about 13.8 VAC with a Scope on a NCE Power Pro 5 amp system.

Sometimes, a slightly lower depending on the load, how many sound locos.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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  • From: Sierra Vista, Arizona
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Posted by cacole on Wednesday, August 22, 2012 7:18 PM

Yes, that's about what you should be reading.  With an el-cheapo ($2.98) Harbor Freight digital VOM I get a reading of 14.2 to 14.6 volts AC from an NCE PowerHouse Pro 5 Amp system.  The Fluke meter is probably giving you a much more accurate measure.

  • Member since
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  • From: Reading, PA
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Posted by rrinker on Wednesday, August 22, 2012 7:26 PM

 You might be surprised, since most RMS meters are calibrated with sine waves in mind, not square waves. The cheapies might actually be a more accurate reading.

 One way to get a better idea, that might work with NCE, is to try measuring the DC volts the Digitrax way - from oen rail to the grouns (case of the NCE booster), and then the other rail to ground. The track output drivers are different between NCE and Digitrax so this may only work with Digitrax, but worth a try. You can also find problems this way - the voltage measurements should eb the same. With Digitrax, if they don;t match, it can be that address 00 is selected and on a non-zero speed, but since NCE can;t do address 00, any significant difference would indicate a problem with the track drivers.

                  --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
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Posted by maxman on Thursday, August 23, 2012 7:19 AM

According to NCE's documentation, the PowerHouse Pro system is factory adjusted to put out 14.25 volts.  This is item 4 on page 3 of the manual.

I believe that it is possible to get a true reading with a "normal" voltmeter, but this requires opening the case.  The procedure is outlined on pages 22 and 23 of the manual.

See: http://www.ncedcc.com/images/stories/manuals/sysman07.pdf 

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  • From: Eastern Shore Virginia
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Posted by gandydancer19 on Thursday, August 23, 2012 1:07 PM

Bruce,  my Fluke 75 reads about what yours does on my Power Pro, and is to be expected.

Although this may not seem accurate for the DCC purest, it is good for using as a reference if you use the same meter all the time.  Most times you will have problems when the voltage is too low, and if you know that the good reading is around 13 volts, you will know there is a problem when the voltage reads less than 10 or 11.

For getting a more accurate measurement for setting booster voltages to match each other, take the readings from inside the case as directed by NCE and not on the track.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

  • Member since
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  • From: Reading, PA
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Posted by rrinker on Thursday, August 23, 2012 6:13 PM

 Totally correct. The absolute reading isn't really critical. Even a cheapy meter isn;t going to say 12V while the thing is really putting 25V on the track and frying every loco you put on the rails. What's critical is a significant differnce from one part of the layout to another, or if you are at the point of adding a second booster, the voltage difference between the two. If the rails on one side of the gap show 13.5 volts and the rails on the other side show 1.45 - you'll see a difference as the loco moves from one section to the other.  

                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

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

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