Transformer compatibility (type, scale, etc?)

Discussion in 'FAQs' started by tverskaya, Jan 2, 2006.

  1. tverskaya

    tverskaya Member

    While planning my layout, and coming to the point of thinking about the electrical part - I came to wonder about the issue of transformers/power packs.

    The trains on the layout will be light, N gauge trains, and there is a small chance that two will be running on one cirquit. The first question: are there differences between transformers made for say H0 and N gauges and will I be needing a specific type. The second question - many, many years ago I had a small layout (1 train, I believe Minitrix, N scale - fate unknown...), for which I believe I had a Jouef transformer, which worked fine as far as I can remember. Later this same transformer was used to power a LEGO train (the good old 12V system), until that was replaced by a 'proper' LEGO transformer, which as far as I know, produced pretty much the same electrical power.

    Now I think at least the LEGO, and *maybe* also the Jouef transformer might still be stored somewhere in an attic, so my question is whether it'd be possible to use either or both for my upcoming little layout without risk of frying the engines on their first run (or not having them run at all, for that matter).

  2. Russ Bellinis

    Russ Bellinis Active Member

    Any 12 volt dc transformer will be compatible. The transformer doesn't care whether the trains are in n scale or ho, 12 v dc is 12 v dc. You need to have a transformer big enough to handle the amp draw of the number of locomotives you want to run at one time. I think most dedicated throttles like Bachmann Spectrum, MRC, etc will be big enough for what you want to do. The exception would be toy train set power packs which are usually just big enough to run what was included with the set. The last statement concerns American sets like Lifelike, Model Power, Bachmann, etc. I don't know what sort of throttles came with the European train sets. The one thing to be careful of is that Marklin, as well as American "O" tinplate like Lionel, Mike's Train House, and K-line use ac power. They are not compatible with dc systems.
  3. tverskaya

    tverskaya Member

    Thanks for the quick reply.

    I guess I'll get by fine with the stuff I have. I expect especially the LEGO transformer to be powerful enough (judging from the immense size of those trains compared to small model trains.)
  4. 60103

    60103 Pooh Bah

    We like to keep the word "transformer" for devices that put out AC (alternating current) power such as the Lionel units and the Marklin.
    We use "power pack" for units with a transformer and rectifier (and usually a speed control and reversing switch) that put out DC (direct current) power.
    As far as I know, all power packs are compatible, producing 12 volt DC, except Z gauge packs are rated for 8 volts (or so) and G gauge packs may have a higher voltage.
    The only other rating is Amperes or Watts (Watts=volts x amps) which limits the power you can draw. You can add locos until the power pack gives up or the circuit breaker goes off. Too many amps will not harm your trains as they only draw what is needed. (It can be a problem if you have a short circuit -- you can weld bits of train to the track with enough power.)
  5. pgandw

    pgandw Active Member

    There are 2 possible problem areas to what you propose.

    1) The power packs you have will supply the 12V DC, and in adequate amounts. But there is a possibility - especially the Lego power pack - that they will do a very poor job of controlling speed (varying the voltage) for N scale locomotives. N scale locomotives draw very little current. If a power pack uses a variable resistance (potentiometer) to drop the voltage (low end power packs usually do), the low current draw of an N scale locomotive requires this variable resistance to be relatively high. The higher current draw of HO and larger locomotives requires this variable resistance to be much lower. The result is that using a small variable resistance with an N scale locomotive often means you can't slow it down.

    2) You mention running 2 trains on the same circuit simultaneously. I hope you meant on the same track, not the same power pack. Running 2 trains on the same power pack means both are controlled the same - you speed up, slow down, or stop at the same time. Since one train is always faster than the other, eventually it will rear end the other when being run from the same power pack. Always plan on having one power pack per train. Then divide the track into electrical blocks which are fed through a SPDT center-off switch. The switch selects which power pack is powering that track block. This way you use the same power pack to control the same train where ever it is on the layout by changing control of the blocks. For a continuous loop to run 2 trains you need a minimum of 4 track blocks.

    yours in wiring
  6. tverskaya

    tverskaya Member

    @60130 - Guess my use of terminology comes from that in the German-Dutch speaking world we're always talking about trafo's. Got to love the variations in terminology :)

    @pgandw - Hmm. So you mean it'll probably work, but it won't be pretty, and eventually I might want to replace them with better quality material. Aww...knew there had to be a difference between the cheap toys and the ones with 'precision control' and such. I have a hunch, that building a speed controller isn't one of the most difficult things to do - am I right?

    And well, that's what I meant, so that'll have to be re-thought as well then.

    Eventually the planning stage will be over - am I looking forward to that? No idea.
  7. pgandw

    pgandw Active Member

    From your posts, I assume you live in Europe. With excellent English, I might add.

    I would imagine you will probably want to replace the power packs you have - eventually. But you can run trains (and have fun) in the interim, and the Jouef pack will probably work fairly well since it came with an N train set. I don't know what the specs or circuits are like in the Lego power pack, so I can only guess that is set up for running large scale trains drawing several times the current of your N gauge motors.

    MRC makes some very nice power packs in the Tech series (2, 3, and 4) using electronic voltage regulation so that the current draw is not a factor. You can get used ones on eBay ($20-$40 US depending on model), but the shipping to Europe might add substantially to the cost. I am assuming from your posts that you live in Europe.

    The most difficult part of building your own power pack is gathering all the parts, and having the knowledge to make suitable substitutions when a specific part is not available. In the U.S., making your own doesn't pay with the MRC power packs prices where they are. I would be hard put to buy all the parts to build one for the price of an MRC, and it wouldn't look nearly as nice. However, I sense electronic parts are much more available in Europe than in the US, so building your own may be more practical.

    Various throttle circuits were published in Model Railroader magazine up through the '70s and '80s. Also, Peter Thone's books of electronic projects for model railroaders had several throttle designs each. This web site has quite a few designs as well:

    Hope this helps.

    yours in powering
  8. tverskaya

    tverskaya Member

    Yep, I'm indeed a Euro. And thanks.

    Guess I'll first concentrate on getting started on the tracks and the scenery with only very basic wiring before getting started on the advanced stuff. The drawings on that website looked a bit daunting.

    Saw that exact train set which I had about twenty years ago for sale on some website. Tempting, but an express-train isn't too much good on a subway track..

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