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Testing signal at track level

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  • Member since
    July 2006
  • 3,312 posts
Posted by locoi1sa on Monday, May 25, 2009 7:41 PM

 Mike

 Voltage and current is 2 different things. You can have 12 volts going through a 30 gauge wire but it will only handle a small amount of current. With DCC its always better to err to the safe side. Typically most DC power packs put out less than 3 amps with variable voltage. DCC boosters will put out up to 10 amps for large systems but typically only 5 amps. Thats enough power to melt ties, wires and could possibly cause fires if the booster does not trip fast enough. Let alone fry decoders and generally make operating hassles like packet loss and signal noise. The best fix is large buss wires and lots of feeders to the rails. In my opinion you cant have too many feeders but you can have too few. Even on good track and wiring I have had feeders heat and burn insulation. My modules have gone through a re wire where the longest feeders have been changed to a larger wire and if it was more than 6 inches long it was spliced to a larger size wire to the buss.

Crandell is correct with the quarter test. It is the most important thing to do on a DCC layout. The booster should trip faster than you can blink. If not there is a problem that needs correction. After that you can place circuit breakers or the tail light bulbs to handle the small intermittent shorts.
   Pete

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Monday, May 25, 2009 7:35 PM

You can read AC volts on the meter, too.  While it's not strictly accurate because the DCC signal is not strictly AC, it is sufficient for checking signal strength.  You should see 12-14 volts AC or so on a DCC track.

It takes an iron man to play with a toy iron horse. 

  • Member since
    August 2001
  • From: NYS
  • 107 posts
Posted by MichaelWD on Monday, May 25, 2009 6:44 PM

 I have a electrical meter that I used on DC to check signal strength. My layout is block control, so I still can run Dc locos. Most of the time the meter is reading around 12 volts. There are some spots that need work.

Thanks 

Mike Dickinson

  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Saturday, May 23, 2009 6:13 PM

Yes, and you will need 25 cents deposit to get the use of the tester.  Go to your change drawer, get a quarter, and place the quarter every couple of feet along the tracks (across both rails) while a DCC signal bearing current is applied normally to the rails.  If the quarter causes a sufficient short that the detection circuitry shuts down the power to your track system, you have sufficient DCC signal to the rails.  Then, restore the equipment to the change drawer and be sure to claim your deposit. Big Smile

If you want a more definitive indication, you'll need either a RAMPmeter or an oscilloscope.

-Crandell

  • Member since
    August 2001
  • From: NYS
  • 107 posts
Testing signal at track level
Posted by MichaelWD on Saturday, May 23, 2009 6:06 PM

 Is there a way to get a reading of the signal strength on the track itself? I am looking into DCC and would like to test all my track before I invest in a DCC system. This is an old layout that has been in progress for a long time

Thanks   Mike Dickinson

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