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Data transmisson on the rails

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  • Member since
    February 2009
  • 4 posts
Data transmisson on the rails
Posted by Part Timer on Saturday, February 14, 2009 8:08 PM

I am new to DCC but am a bit familiar with electronics.  I bought a new NCE Power CAB and a few locos with sound.  Genesis F7, BLI steam, others.  I use KATO HO track.  The system worked great on a test oval on a 4x8' .   When I enlarged the oval to a 4x18' and added a passing siding and a yard, BLI is extremely eratic. (chuffs but runs erratically)  All other decoder equipped locos work fine.  I use a #12 stranded pair with at least 3 twists per foot feeding both sides of the oval.  Adding this did not improve the BLI. 

Tags: bus wires , DCC
  • Member since
    January 2001
  • From: SE Minnesota
  • 6,847 posts
Posted by jrbernier on Saturday, February 14, 2009 8:27 PM

 Welcome to the Forum!

  I suspect your problem is electrical pickup in that engine as the other operate fine.  Maybe just the wheels are dirty.  The 'twist' is fine, but is not really needed for noise cancellation.  As I understand it, you have a 'bus' all around the mainline?  How often does the track tap into the bus via feeders?

Jim

 

Modeling BNSF  and Milwaukee Road in SW Wisconsin

  • Member since
    February 2009
  • 4 posts
Posted by Part Timer on Saturday, February 14, 2009 8:35 PM

It is not really a bus, just 2 places connect to the power.  I eventually plan a 10x30' room with the tains travelling the perimeter.  Thus the concern for data propagation.  The wheels don't look dirty and the train is brand new out of the box.  I onl;y ran it on the oval a few times and the track is also brand new.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Saturday, February 14, 2009 8:49 PM

What's the wheel configuration of the BLI steamer?

If you've built an oval on a 4x8, and used the traditional 18-inch radius sectional track to do it, you may have built in some bad track connections.  More feeders will help, as will soldering the rail joiners.  On the other hand, if the other engines work OK, you may not have that problem.

Longer engines like larger radius curves.  My BLI Hudson is forgiving.  It will work quite nicely on 18-inch curves, but the trackwork has to be perfect - no dipsy doodles, no kinks, no problems.

One thing I had to do was put the loco-tender spacing at the wider of the two available settings.  The close-coupled setting looks better and is more prototypical, but it won't work around those 18-inch curves.

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

  • Member since
    February 2009
  • 4 posts
Posted by Part Timer on Sunday, February 15, 2009 6:32 AM
I admit I am using the 550mm radius as the tabletop is 4' x 18''. The loco is set to the most distant hole at the tender coupler. Loco ran fine with the same radius but shorter distance ( 4; x 8' ). I am concerned when folks talk about soldering the rails. Using an expensive track like KATO usually precludes hosing it up with solder joints. Main reason for using KATO in the first place. I do thank all you folks for replying. More ideas the better!
  • Member since
    January 2001
  • From: SE Minnesota
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Posted by jrbernier on Sunday, February 15, 2009 11:29 AM

  Get an electrical Multimeter(VOM) and on the AC scale; check your track voltage at various places around the layout.  They shold all be the same.  If not the Kato Uni-Track joiners may need to be replaced.  Usually the Kato track is 'Bullet-Proof', but I am sure they can wear out.  I do not feel you have any 'data propagation' issues here.  Since the other engines work fine, the problem is in that engine.  From you description, it sure sound like an electrical pickup issue.

  I agree with you - soldering that Kato track will be hard!

Jim

Modeling BNSF  and Milwaukee Road in SW Wisconsin

  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Sunday, February 15, 2009 12:07 PM

One easy and common thing to check with BLI steamers (unfortunately, because I have several) is the tether between the tender and the engine cab.  It is often the case that the connector has backed itself out due to forces on the wires.  This is especially true on tighter curves. 

Take a bamboo kabob skewer and jam the connector home.  Work it in with a prying motion on both sides of the connector's wire bundle using the flanges to the sides.  You may get lucky and find that this, only, is your problem.

  • Member since
    February 2009
  • 4 posts
Posted by Part Timer on Tuesday, February 17, 2009 6:15 PM

I think this is the problem.  Exchanged loco.  Problem gone.

 

 

Thanks all.

  • Member since
    July 2006
  • From: Vail, AZ
  • 1,943 posts
Posted by Vail and Southwestern RR on Tuesday, February 17, 2009 7:11 PM

I realize this problem is solved, but for future reference... 

jrbernier

  Get an electrical Multimeter(VOM) and on the AC scale; check your track voltage at various places around the layout.  They shold all be the same. 

This is good advice as far as it goes, but.....

For this readings to really be meaningful they need to be taken under a loaded condition.  It is pretty likely that even a poor rail connection (whether it is Kato, or fishplate joiners, or whatever) will be able to handle the very small current the VOM draws to make the measurement, and the voltage will appear good everywhere.  As soon as there is a real load, however, there will be a significant voltage drop across the bad joint.  I've never thought about this, but I think something like a 50 Ohm 4W power resistor might make a good tester for this.  Someone can check my math on that, just to make sure I haven't slipped a decimal in my head.  I'm thinking of drawing around a quarter amp (like a hefty loco) to check the voltage drop.

Jeff But it's a dry heat!

  • Member since
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  • From: Reading, PA
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Posted by rrinker on Wednesday, February 18, 2009 6:33 AM

 With 14.5 volts to the track (common HO DCC setting), a 50 ohm resistor will draw a bit over 1/4 amp - .29 amps to be exact. And dissipate about 1.5 watts, so a 4 watt resistor gives you breathing room. If you can;t get a 50, two 100 ohm resistors in parallel would be 50 ohms.

                                  --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
    July 2006
  • From: Vail, AZ
  • 1,943 posts
Posted by Vail and Southwestern RR on Wednesday, February 18, 2009 12:32 PM

rrinker

 With 14.5 volts to the track (common HO DCC setting), a 50 ohm resistor will draw a bit over 1/4 amp - .29 amps to be exact. And dissipate about 1.5 watts, so a 4 watt resistor gives you breathing room. If you can;t get a 50, two 100 ohm resistors in parallel would be 50 ohms.

                                  --Randy

It's nice to know the grey matter is still working!

 

Jeff But it's a dry heat!

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