Loop Wiring/Multiple Power Packs

Discussion in 'FAQs' started by Bob Collins, Jan 31, 2002.

  1. Bob Collins

    Bob Collins Active Member

    Shamus, et al

    Shamus, I tried to send you a private note so as not to take uop space here, but was notified your box is full and what the heck, maybe others are struggling with this sort of thing just like me.

    I am back to my loop wiring problem. I have in front of me your wiring diagram. I also have an Atlas #220 controller.

    Is this the kind of controller you reference in your diagram, or something similar?

    My other question is: what makes it necessary to have more than one power pack. Is it simply based on the number of cabs you wish to operate? I am block wiring which I know makes a difference:)


    Anyone else who wants to add their 2 cents worth please jump in. I can always use all the help I can get!!
  2. Gary Pfeil

    Gary Pfeil Active Member

    Bob, Pictures are always so much better than descriptions when talking wiring, but since I don't know how to post one, I will attempt to make a clear explanation of what is required. First, I'll talk about one train operation. Buy two dpdt switches, where you have 6 terminals on the back, arrainged in two rows of three. Draw three dots on a piece of paper, from left to right, then another row beneath it. This is the orientation I will use to explain wiring. Connect the upper left terminal to lower right, and lower left to upper right. This gives you an"x". Do this to both switches. Either outside pair of terminals is connected to your power packs output. The center terminals go to the track. by using one switch for the main line and one for the reverse loop, you now can change polarity in one without affecting the other. The direction switch on the power pack would not be used. Some power packs have two swithes on them, with two outputs, one marked reverse loop. When I used DC, this is the way I wired loops. While the train is running thru the reverse loop, you can change polarity on the main so you can run uninterrupted back onto the main.
    Now, for multiple train operation, you need a cab (power pack) for each train. For two trains, you can use toggles, where each electrical block of your track is wired to a dpdt switch which connects the block to either of two cabs. Each of the cabs would need the polarity switches as described above. The polarity switches need to come before the cab switch. Bear in mind that when changing polarity for the main line, all blocks connected to that cab will be changed, so center off toggles are a good idea. The wiring for the cab selector switch is similar to the above, the center terminals go to the track, the outer ones are inputs from the respective cabs, there is no "x" wiring on these.
    For more than two train operation, you would need to use rotary switches instead of toggles.

    Hope this helps, Gary
  3. Bob Collins

    Bob Collins Active Member


    Thanks very much. You do quite well with words and without a picture. It is quite clear ro me what you are saying. I will give it a try and see what develops.

    It is interesting that I actually have two loops. One of them is very easy to iderntify while the other is more complex. I may have to sit down and try to draw a picture to post here so you and others can see what I am dealing with.

    I think I'll use your guidance and try to do the simpler one and them see about doing some drawing for the other one.

    Thanks again.

  4. billk

    billk Active Member

    Bob -

    One thing I've found to help is to diagram your layout showing both rails. Doesn't have to be to scale, it just needs to show how everything goes.

    After you've done that, start somewhere on it that you know is not in a loop and draw along one rail with one color and the other one in a different color (say red and green).

    If you ever get to a point where a red rail is hitting a green rail, bingo!

  5. shamus

    shamus Registered Member

    Hi Bob,
    There is no need to use rotary switches if you just need two controllers and complete cab control.
    Here is my complete wiring system I have developed over many years.
    If you get stuck, email me at shamus@the-gauge.com


  6. Gary Pfeil

    Gary Pfeil Active Member

    Bob, A quick note on Shamus's drawing: Using one switch (for the reverse loop) and the direction switch on the power pack as the other (as opposed to the method I described above) is somewhat simpler at the cost of needing to stop your train in the reverse block in order to change polarity on both switches. Of course you could just throw both while the train is moving and if you do so at the same time you will just see a moments hesitation. I used two switches to avoid this. Also, the switch for the reverse block (on the right in the first drawing) shows the leads from the power pack and to the track reversed from what I described, either will work.


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