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Accessory lights dimming momentarily

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  • Member since
    September 2008
  • 43 posts
Posted by ballastbob on Monday, February 8, 2010 7:38 PM

 Bob,

Moved the block signals to the accessory posts on the ZWs and solved my problem. Thanks for your help.

Bob

  • Member since
    September 2008
  • 43 posts
Posted by ballastbob on Monday, February 8, 2010 10:10 AM

 Thats exactly what I plan to do.  Thanks so much for your help.

Bob

  • Member since
    December 2001
  • From: Austin, TX
  • 10,096 posts
Posted by lionelsoni on Monday, February 8, 2010 9:04 AM

Again assuming my guess about the source of the problem is right, no.  Higher voltage would just increase the currents all around and get closer to the CW-80's limit.

How about moving all the accessories to one of the ZW outputs as an experiment, to see whether the flicker goes away?

Bob Nelson

  • Member since
    September 2008
  • 43 posts
Posted by ballastbob on Sunday, February 7, 2010 10:52 PM

 Thanks, Bob. These are indeed block signals with colored lights.  I think I ll try shifting some of the load to one of the ZWs.  I presume from your answer that increasing the variable voltage output from the CW is not a very good solution.

Bob

  • Member since
    December 2001
  • From: Austin, TX
  • 10,096 posts
Posted by lionelsoni on Sunday, February 7, 2010 10:09 PM

When you say "block signals", do you mean color-light signals?  If so, the problem could be that the CW-80 is close to its current limit.  Incandescent lamps' resistance varies greatly with filament temperature, roughly a factor of 10 between cold and fully lit.  It could be that, when a signal switches, that tenfold increase in current pushes the electronic foldback arrangement in the CW-80 over the edge for a moment.  The foldback then exacerbates the situation by delaying the warmup of the filament.

This behavior is the sort of "nuisance tripping" that I don't like about fast-acting overcurrent protection.  It doesn't happen in traditional simple transformers because they use slow-acting thermal circuit breakers which model the harmful effects of overcurrent on the transformer and layout wiring and don't trip until the wiring has had a chance to overheat.

If this is the explanation, an obvious fix is to transfer some load from the CW-80 to some other source.  You could experiment with reducing the load to see whether that does fix the flickering.  There is a trick that could allow you to get by with all of it on the CW-80.  It is to put resistors around the contacts (or control rails) that you are using to operate the signals.  The idea is to run a continuous current into the lamps that are off, not enough to light them up but enough to keep them as warm as possible short of lighting.  Then there is much less of a current surge when the contact closes.  The downside of this is that the resistors for your 4 signals may all together draw more current than the CW-80 can put out.  But it might work.

Bob Nelson

  • Member since
    September 2008
  • 43 posts
Accessory lights dimming momentarily
Posted by ballastbob on Sunday, February 7, 2010 9:32 PM

 Lionelsoni could you help me with this?

I have all my operating accessories including four block signals connected to a new CW-80 used exclusively for accessories.  All the accessories are wired in parallel except for one feeder wire supplying a string of leds wired in series with resistors.  I use a layout common connected to the CW-80 and a couple of postwar ZWs.  The variable output is set to about 13 volts.  Everything works OK except when the trains activate one of the block signals all the accessory lights dim momentarily.  Is the solution simply to increase the amount of voltage supplied or should I look for another problem?

Bob

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