Power Packs

Discussion in 'N / Z Scale Model Trains' started by CAS, Apr 13, 2005.

  1. CAS

    CAS Member

    I am shopping for some power packs, or are they still called transformers?

    All i have is some small transformer.
    I went to www.modelretifier.com and saw a couple that i need some input on.
    What you guys think about these i choose? I want to grow into them. I would rather spend the money now for a real good one, then use the one i have.

    1 - Tech 4 MRC 260 with 20 Va + Momentum
    2 - TrainPower 6200 60 Va.

    I would really appreciate your true opinions on these, our can you recommend some other ones.

    I will be using DC.

    Thanks, Cliff
  2. brokemoto

    brokemoto New Member

    I assume that you are going to use DC and not DCC.

    I do not use the packs that you mentioned.

    I do use MRC packs, but I assume that the ones that I use are now out-of-production. This is not a big deal, as many places have them as NOS.

    My favourite is the TECH II 2400. It has an ON-OFF pulse switch and is a reliable pack. I have some that I have been using for ten years: the MRC warranty is five.
  3. 60103

    60103 Pooh Bah

    Technical terms: a transformer takes AC from the wall and produces lower voltage AC for the track. This is suitable for Lionel and American Flyer "toy" trains.
    A power pack contains a transformer, a rectifier, a reversing switch and a speed control. This produces DC for the other trains. You can also get throttles which are power packs without a transformer. Some of them have extra fancy electronic bits in them.
    The power of the packs you mentioned: Va is Volts x Amps (used to be called Watts). Divide this number by 12 to get the power in amps at 12 volts. Used to be, we consider a motor drew 1 amp. Newer ones draw less than 1/2 amp, maybe 1/4 amp. The 16 Va will be 1 1/3 amps which is one old loco or 2-3 new ones.
  4. TrainNPlaneMan

    TrainNPlaneMan New Member

    Place For information and transformers

    http://indyntrains.com Has alot of good information and transformers.

    There Site has been down a few times so i dunno if you'll find the info you will need but it's worth a try.[​IMG]
  5. hooknlad

    hooknlad Member

    Hi again all, I have a question for everyone. I have a little knowledge of DCC and would like to buy a decent system. I realize that I'll have to invest better than $200 for the system. Is it necessary to utilize the transformer that they provide and keep adding booster packs to the system for more trains? Does anyone know the specs for the output of these transformers. As an Electrical Engineer, I have access to many ac and dc accessories to build a pristine power supply of 20 amperes. Just curious. I probably should just adhere to the manufacturers recommended specifications and use compatible systems.
  6. ezdays

    ezdays Out AZ way

    You might be better off checking the DCC forum here, someone there should be better prepared to give you an answer.
  7. ezdays

    ezdays Out AZ way

    I have two Tech 4, 350's, and one 250 which they no longer produce. Like the 260, they all have momentum and breaking which is achieved by speeding up and slowing down a series of DC pulses. The only difference between them is the total power (VA or watts) output. They are good products, and are essentually bullet-proof in that they "fold over" (go to zero volts) if there is a short or overload.

    You have an answer here already about transformers. Any transformer will simply take one AC voltage and convert it to a different voltage. A power pack takes that a step further and converts the AC to DC, which is necessary for running a lot of stuff including engine motors and some accessories. Just about anything electronic that plugs into a wall outlet has a transformer and power pack built into it. Radios, TV's, computers and DVD players are just a few. In the case of TV's and CRT computer monitors, the transformer converts some voltage higher to run the video tube, and some lower to run the electrinics. In the world of MRR, the transformers and power packs are always separate.
  8. MasonJar

    MasonJar It's not rocket surgery

    Sometimes they are not always separate in the minds of modellers though... especially ones like me :D ;)

  9. ezdays

    ezdays Out AZ way


    I meant separate from the devices they run, sorry for any confusion.

    I do agree with you, a lot of modelers use these terms interchangable. A transformer is just that, AC in AC out. A power pack most always has a transformer in it and may just have one or more diodes and maybe a capacitor to convert to DC, or even a regulator to keep the voltage constant. The Tech 4 supplies have some additional electronics necessary to achieve the momentum and breaking and other features.

    There are schematics available for building your own momentum power pack, and I was getting ready to do it when I found the Tech 4 350's on sale for $65 each and it just wasn't worth the effort anymore.
  10. 60103

    60103 Pooh Bah

    I would suggest that you not build a 20 amp power supply. I was at a DCC seminar and they said that 20 amps can do many intersting things to wheels and trucks if you have a derailment, or other short. The idea is to divide the layout into Power Districts that have up to 5 amps each. 5 amps will run 5 locos cetainly and probably 10 or 15 modern ones. If they are wired properly, you can move between power districts without a blip.
    We used an old MRC pack to power a Lenz system; I don't think there's anything special about the transformer.
  11. toolman

    toolman Member

    Cas, if you go to your hobby/modelrailroad shop that you use and they have power paks on display or use on the store layout if have to get the feel, etc. If you use a hi amp power pak you can fused the output to the track to a lower ampage fuse in 1-3 amp range.
    I rebuilt an old mrc model 501 throttlepack with a bridge rectifer rated at 25 amps, but have fused at 3amps, even then I can still drop down to about 2 amps. I do not have dcc so I am not worried about the amps.

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