Q - Power routing turnouts & DCC

Discussion in 'FAQs' started by spitfire, Apr 18, 2006.

  1. spitfire

    spitfire Active Member

    I've read that power-routing turnouts are not "DCC-friendly". But what about using them for stub-ended tracks in a yard?

    I want to use dwarf signals on my yard ladder. If I could use power-routing frogs, I could simply wire the lights to the track. Throw turnout, send power to that track and the signal.

    The alternative is costly $witch machine$. I'm using Peco turnouts so I don't even need them otherwise.

    Thanks in advance for the help. :wave:

  2. 60103

    60103 Pooh Bah

    Val, both types of Peco turnout have some form of selective power. On the electrofrog as supplied the un-selected routes has both rails at the same polarity. On the Insulfrog turnouts, the rail through the frog is dead.
    As long as you don't feed power from beyond the frog, either should do what you want.
    There may be concerns about the power drain of the lights on your DCC system. Someone else will have to talk about that.
  3. spitfire

    spitfire Active Member

    Thank-you Andrew - that is very helpful info. I would not be feeding power on the other side of the turnout in that scenario.
    One thing I don't understand. "The un-selected routes has both rails at same polarity". Same polarity as what?
    Which one of these turnouts (if any) behaves like a switch, letting power through the frog one way and blocking it the other?

  4. billwv

    billwv Member

    Hi Spitfire,

    For a complete discussion of PECO turnouts, and everything you ever wanted to know about them and DCC, see Loys Toys--bottom of page at this link:


  5. Gary Pfeil

    Gary Pfeil Active Member

    Val, Power routing turnouts need to be powered from the point end of the turnout. I can't speak for Peco, Shinohara and handlaid turnouts basically route the power from the stock rails down both points, closure rails and frog. Which polarity is present is determined by which way the points are thrown. Whichever stock rail has a point against it will have its polarity on all rails of the turnout except the opposing stock rail. Since the electrical connection of the point rail against the stock rail is suseptable to poor contact, microswitches are usually added to route the power to the frog. So, one route, the one which is not selected, will have both rails the same polarity, in effect creating a "dead" track which with DC you could park a loco on and not need a seperate electrical switch to cut off power. There is no reason I can see that power routing turnouts are not DCC friendly, as long as the modeler knows to gap the rails beyond the frog. With DCC, the benefit of not needing that electrical switch to kill power to a track obviously is not required. So, one big benefit of power routing turnouts is removed for DCC. However, I'm a big fan of powered frogs so still prefer this setup.

    Go ahead and power your lamps or leds from the track power, there current requirement is small and shouldn't affect operations. Oh, leds may require a diode in addition to the dropping resistor,since track power is ac. Someone else will chime in I'm sure.
  6. spitfire

    spitfire Active Member

    That sounds good for a yard ladder.

    Wouldn't that be a short circuit?

    So, you'd need a gap beyond the frog, and then separate power feeds to the rails beyond the gap?

    Right, but in my case I'm using that "electrical switch" to turn on and turn off the signal lights. Also, those metal frogs just look so much better. :D

    Thanks Gary. I really appreciate the explanation. And Bill, thanks for the link. :thumb:

  7. Gary Pfeil

    Gary Pfeil Active Member

    Hi Val, Wish I remembered how to quote from your post, but I'll try to answer each question.

    1 It is great for a throat to stub ended tracks. You want to use handthrows, right? The Pecos do a good job of routing power with their clips in indents on the throwbar. Sounds like the electro frog turnouts route as they come, so you could use them with no additional feeds and no gaps and not have a problem, as long as all those railjoints never allow bad contact and voltage drop becomes an issue. If a joint becomes a problem, you can gap and add leads as required. If that's something you want to possibly deal with later. It would probably be fine to go ahead and solder all your rail joiners. Some don't like that. Adding leads later is often no problem, depending on access. Determining where to add gaps is easy. Perhaps someone will post a diagram or link to one. But here is how you figure it out. Oh, and I answer your next question.

    2 A short is a connection of opposite polarities with little to no resistance. Since both rails of a diverging route are the same polarity, there is no short. There is no complete circuit. So, if you look at a drawing of a ladder with the track coming in from the left and the throat extending to the right, and the top rail is marked positive and the bottom negative, you can follow the positive and negative routes. When you get to a frog, remember that all rail connected to that frog will become whatever polarity you have connected the points to. So one route will be live, the other dead, for its entire length. You then reach the next set of points and the process repeats. If you have to add a feed ( and lots of times cleaning and soldering an offending railjoiner is all it takes) do so wherever needed, and gap just before it. Connect the feeder to the appropriate bus. Just remember north rail always white, south rail always black, or whatever color you use. The trackage above the gap will no longer control the polarity of the trackage below it. So, depending on where the new feed is, another track will stay powered, defeating your signalling scheme, but otherwise will work well.

    Actually, I think I've answered the other questions too. Hope it was clear enough to make sense of. A drawing would be good!
  8. 60103

    60103 Pooh Bah

    Val: lets call the far rail N and the near rail S. I'll assume a turnout with the diverging route away from us.
    If the turnout is set straight, the nearest through rail is S, the far through rail (to the siding) is N. The far point is N and this continues through the frog and out onto the mainline.
    Now for the conditions. If you have insulfrog, the near point rail is neutral, since it isn't connected to anything. This continues areound the curved rail, through the frog and into the siding. So the siding has N and neutral power and nothing moves.
    If you have an electrofrog as supplied, the whole frog is wired to the N point eail, and back down the other point rail (to the space between it and the stock rail) and out the rail past the frog into the siding. So both siding rails are the same polarity (N) and nothing moves.
    If you change the point, on the Insulfrog, the frog siding rail becomes S and the mainline rail becomes neutral. If you have put feeders beyond the frog in the mainline (or have an oval) the rail could have a potential from there but won't cause problems because the point doesn't touch anything.
    On the Electrofrog, the frog siding rail changes from N to S as does the mainline rail beyond the frog (Both mainline rails are now S) as are both points. Now if you have feeders beyond the frog, the N feeder conflicts with the S through the frog. Here you need your gap.
    Maybe if you take one turnout and clip some wires and a voltmeter to it you can trace what happens. (and a few Xmas tree lights to make it pretty.)
  9. spitfire

    spitfire Active Member

    Thank you very much Gary and David. Just so you know, I had to read your answers verrrry carefully, :rolleyes: but I'm pretty sure I understood them both.

    So, what I'm thinking would work is if I solder the yard ladder together, and also solder the yard tracks, using power-routing Peco turnouts. I will hook up my lights on the far side of the frog.... more questions will probably arise around that, but I want to keep it as simple as possible. I chose Peco because I like that they can be thrown by hand.

    I am planning right now to re-do the yard. I used Peco "Set Track" turnouts, which are the tightest radius they have -- too tight for the BLI switcher really. I will replace these with either the regular Peco smalls, or maybe go with the mediums. I would rather sacrifice a couple of spaces for cars and gain smooth, trouble-free operation.

    Thanks again for your help! :thumb:

  10. 60103

    60103 Pooh Bah

    Wow, Val, you managed to get settrack turnouts? I didn't think they were sold over here.
    I think they're 17 1/2" radius. Almost a match for snap track.
    See if you can sell them to Chris for his traction layout. sign1

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