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memory test on older analog power base

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  • memory test on older analog power base

    picked up couple of those older scaly analog power bases that could take 1 or 2 power packs

    the scaly power packs say they put out AC and power base make it into DC

    my experience is with other brands whose power packs put out DC directly

    and want to pump DC into these scaly bases too

    however remember a conflicting discussion here on SCI about 10 or more years ago about this topic

    so any thoughts from experienced old timers now ?
    Last edited by gorp; 08-19-2018, 03:19 PM.

  • #2
    It will work with dc, but it'll be able to deliver more current from ac power supplies.
    The current available from a dc input might be sufficient for your cars, it depends on how much current your cars are taking.

    If you want a techy explanation:-
    It uses a circuit called a bridge rectifier to convert ac to dc. With an ac input that circuit shares the work between 4 diodes, with a dc input it shares the work between just 2 diodes. So with a dc input at high currents those two diodes are overloaded. When using these power bases on dc the diodes themselves rarely fail because the copper track leading to them usually fails first.

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    • #3
      A simple power supply consists of a step down transformer and a rectifier. With some track systems there is a wallwart transformer that plugs into the power base, and the power base only contains the rectifier. In other cases the power base includes both the transformer and rectifier. If your power base only contains the rectifier you can connect a DC supply to it and you will get DC to the track, however the diodes in the power base will drop the voltage somewhat.
      If your power base includes a transformer that will not pass DC, so if you connect a DC source there will only be a very brief blip at the output of the power base, then nothing.

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      • #4
        Thank you Al's and Rich.

        One thing has confused me.
        How often does copper track fail with power bases ?
        Does AC/DC or DC/DC make a difference ?

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        • #5
          Originally posted by gorp View Post
          How often does copper track fail with power bases ?
          The copper tracks within the power base don't fail when they are taking the current they were designed for.
          Higher currents can arise due to a fault in the car or track AND a power supply that can deliver high enough current to cause failure of the power base.

          Originally posted by gorp View Post
          Does AC/DC or DC/DC make a difference ?
          Yes
          In this type of power base when used with a dc input, the copper tracks typically fail at very roughly half the current that would cause failure with an ac input. (What we are talking about are Scalex power bases that are designed to convert low voltage ac to dc. It doesn't apply to other sorts of power base.)

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          • #6
            Thank you again Al's.

            Your current is amps, so will reconsider using higher amp alternative power.

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            • #7
              Originally posted by gorp View Post
              Your current is amps,
              Not sure if that was a question
              Amps are the worldwide standard unit of measuring current.

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