Loading ...
Sorry, an error occurred while loading the content.
 

Re: [Z_Scale] Re: Z SCALE

Expand Messages
  • Tony Dalileo
    dear alan so the reason my engines run independantly on the 2 loops with 2 power packs is that i havent gone across the gap. i have burned out the front
    Message 1 of 10 , Aug 3, 2010
      dear alan

      so the reason my engines run independantly on the 2 loops with 2 power packs is that i havent gone across the gap. i have burned out the front lights on my a-b-a engine set.

      what i dont understand is when both loops are in difference directions then i have the plus side of one pack connected to the neg side of the other pack via the common rail why dont i get a short?

      could the fact that the powerpacks are connected to the tracks via a 8590 terminal track which has a interference isolated between the pack and track. i assume that its for radio interference prevention but could it also be isolating the power packs and somehow allows the opposite polarity of 2 packs to be connected and not short out


      tony



      --- On Tue, 8/3/10, Alan Cox <alan@...> wrote:

      > From: Alan Cox <alan@...>
      > Subject: Re: [Z_Scale] Re: Z SCALE
      > To: z_scale@yahoogroups.com
      > Date: Tuesday, August 3, 2010, 1:24 PM
      > On Mon, 2 Aug 2010 22:42:52 -0700
      > (PDT)
      > Tony Dalileo <tony_mrr@...>
      > wrote:
      >
      > > dear garth
      > >
      > > my layout only isolates only one rail using marklin
      > 8588 isolation track.
      > >
      > > is there no way to have a common ground
      >
      > You just need to be a bit more careful about when
      > locomotives or stock
      > can span the gaps. Avoiding a common ground doesn't really
      > avoid that
      > either - merely makes it less likely. Even without a common
      > you can end
      > up with a wheel across the gap on one rail and the voltage
      > difference
      > across the trucks the other side. Ditto with Maklin
      > overhead and a loco
      > on the track backwards.
      >
      > As far as I can tell (on the basis of having done this a
      > few times)
      > Märklin stock is at least engineered to survive brief
      > incidents of this
      > type. The modern Marklin power units also seem to be
      > reasonably smart
      > about shorts.
      >
      > For loops I see no reason to connect one side of the
      > supplies together as
      > it's not as if it makes the wiring much simpler - for block
      > sections it
      > can although there at least you can have an intermediate
      > block which can
      > be switched from one supply to the other - something you
      > don't have room
      > for between loops usually.
      >
      > Alan
      >
      >
      > ------------------------------------
      >
      > Z-scale:  minimum siZe, MAXIMUM enjoyment!
      > Yahoo! Groups Links
      >
      >
      >     z_scale-fullfeatured@yahoogroups.com
      >
      >
      >
    • Alan Cox
      ... Short answer: because electricity doesn t work like that - it s all relative. So providing there is only one side cross connected anywhere (which is the
      Message 2 of 10 , Aug 3, 2010
        > what i dont understand is when both loops are in difference directions then i have the plus side of one pack connected to the neg side of the other pack via the common rail why dont i get a short?

        Short answer: because electricity doesn't work like that - it's all
        relative. So providing there is only one side cross connected anywhere
        (which is the case with a common return and Märklin controllers as they
        each have their own transformer) then if you join them together one one
        side that simply becomes a common voltage between the two. Join both
        together and bad things happen.

        If you join one side together and then connect a voltmeter across the
        other two you'd see a voltage that varied according to how you turned the
        knobs. With one on zero and the other turned you will see the voltage for
        that one (-8 to +8 or thereabouts), turn them both the same way and you
        will see a low voltage or even 0 if they were turned the same amount.
        That is of course the normal case when you run a train between loops -
        there is little voltage difference between the two loops.

        The bad case is if you turn the knobs in opposite directions, you will
        then see up to + or -16v on the voltmeter, which is more than the models
        are designed to take in normal use.

        They are a good deal more robust than you might think however because
        they are designed to survive a variety of situations where the model
        carries more power than you would like - just as they get a certain
        amount of 'will it bounce' considered in the design strength.

        Other scenarios that are usually considered in designing models include

        - derailment where one truck comes off the track and ends up with the
        wheels shorting the other rail. At this point the short is through the
        wires in the locomotive

        - Similarly where a locomotive moves from one section to another which
        already contains a locomotive that is currently not being fed power. At
        that point the second locomotive is potentially being powered through
        the wiring of the first.

        - Running through electrofrog points the wrong way

        - Putting a locomotive using overhead on the track the wrong way around

        But 16v across a model designed for 8 isn't very good for it - especially
        if its more than briefly.

        Alan
      • Tony Dalileo
        thank you how come my meter reads 14v dc on a marklin z power pack with no load on the track when model max is 8v dc can i isolate the other rail by putting a
        Message 3 of 10 , Aug 3, 2010
          thank you
          how come my meter reads 14v dc on a marklin z power pack with no load on the track when model max is 8v dc


          can i isolate the other rail by putting a cut in the uncut rail on a marklin 8588 isolation track or will that not work


          tony



          --- On Tue, 8/3/10, Alan Cox <alan@...> wrote:

          > From: Alan Cox <alan@...>
          > Subject: Re: [Z_Scale] Re: Z SCALE
          > To: z_scale@yahoogroups.com
          > Date: Tuesday, August 3, 2010, 5:04 PM
          > > what i dont understand is when
          > both loops are in difference directions then i have the plus
          > side of one pack connected to the neg side of the other pack
          > via the common rail why dont i get a short?
          >
          > Short answer: because electricity doesn't work like that -
          > it's all
          > relative. So providing there is only one side cross
          > connected anywhere
          > (which is the case with a common return and Märklin
          > controllers as they
          > each have their own transformer) then if you join them
          > together one one
          > side that simply becomes a common voltage between the two.
          > Join both
          > together and bad things happen.
          >
          > If you join one side together and then connect a voltmeter
          > across the
          > other two you'd see a voltage that varied according to how
          > you turned the
          > knobs. With one on zero and the other turned you will see
          > the voltage for
          > that one (-8 to +8 or thereabouts), turn them both the same
          > way and you
          > will see a low voltage or even 0 if they were turned the
          > same amount.
          > That is of course the normal case when you run a train
          > between loops -
          > there is little voltage difference between the two loops.
          >
          > The bad case is if you turn the knobs in opposite
          > directions, you will
          > then see up to + or -16v on the voltmeter, which is more
          > than the models
          > are designed to take in normal use.
          >
          > They are a good deal more robust than you might think
          > however because
          > they are designed to survive a variety of situations where
          > the model
          > carries more power than you would like - just as they get a
          > certain
          > amount of 'will it bounce' considered in the design
          > strength.
          >
          > Other scenarios that are usually considered in designing
          > models include
          >
          > - derailment where one truck comes off the track and ends
          > up with the
          >   wheels shorting the other rail. At this point the
          > short is through the
          >   wires in the locomotive
          >
          > - Similarly where a locomotive moves from one section to
          > another which
          >   already contains a locomotive that is currently not
          > being fed power. At
          >   that point the second locomotive is potentially
          > being powered through
          >   the wiring of the first.
          >
          > - Running through electrofrog points the wrong way
          >
          > - Putting a locomotive using overhead on the track the
          > wrong way around
          >
          > But 16v across a model designed for 8 isn't very good for
          > it - especially
          > if its more than briefly.
          >
          > Alan
          >
          >
          > ------------------------------------
          >
          > Z-scale:  minimum siZe, MAXIMUM enjoyment!
          > Yahoo! Groups Links
          >
          >
          >     z_scale-fullfeatured@yahoogroups.com
          >
          >
          >
        • Alan Cox
          On Tue, 3 Aug 2010 13:34:11 -0700 (PDT) ... Put a load on it. The newer ones are also quite smart and don t simply output 0-8v smoothed DC but know how to give
          Message 4 of 10 , Aug 3, 2010
            On Tue, 3 Aug 2010 13:34:11 -0700 (PDT)
            Tony Dalileo <tony_mrr@...> wrote:

            > thank you
            > how come my meter reads 14v dc on a marklin z power pack with no load on the track when model max is 8v dc

            Put a load on it.

            The newer ones are also quite smart and don't simply output 0-8v smoothed
            DC but know how to give better motor control than that.
          Your message has been successfully submitted and would be delivered to recipients shortly.