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Re: Trafos And Voltage And Locs, Oh My!

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  • viktor_kovacs
    ... I have three different trafos from marklin. The oldest, designed for 220V is clearly out of spec when used with the current european 230V network. It
    Message 1 of 21 , May 4, 2008
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      --- In z_scale@yahoogroups.com, "Mark Edwards" <mrex@...> wrote:
      > Hi Guys, I just got my hands on those two beautiful MTL locs I
      > mentioned in my last thread, a Chessie GP35 and Santa Fe GP9. After
      > carefully reading the instructions, I noted the warning that these
      > locs use a 9 volt motor, and will burn out if run at higher voltages.
      > Am I correct in assuming that I can blow these locs with my Marklin
      > 67271 10 volt trafo?
      > I got worried enough about this that I metered my trafo, and thank god
      > I did! While its rated at 10v, its actually putting out *15v* under
      > no load at max setting. I made a point of finding out where the 9v
      > limit was on the knob, and also metered the track while the locs were
      > running to make sure I got it right. (On my trafo, that setting is
      > "140 kph".)

      I have three different trafos from marklin. The oldest, designed for
      220V is clearly out of spec when used with the current european 230V
      network. It outputs 18V without load. The newer one works right, it
      outputs 12V max, which is a bit too much, but not really dangerous.
      The newest marklin 'trafo', which is just an LM317 chip powered by
      a standard 'wall wart' power brick. It takes 11V DC on its input
      and outputs around 10V max. on the output. The accessory output
      just gets the raw 11V _dc_. (the outputs actually have a common
      rail ground) This is still more than 9V, but can't burn out the
      locos. The LM317 is also short circuit protected and current limited.

      Running mtl trains with the new trafo should be ok, but if you are
      worried, you can get a 10V wall wart so the output will be always
      at or below 9V.

      > I also searched the posts on this forum and ran into cautions about 8v
      > and 9v Z motors, but nothing on actually burning out locs with Marklin
      > trafos. Are these trafos simply "hot", and users have to be careful?

      Some are dangerous, some aren't. As long as you don't turn the trafo
      up too high, you can run marklin z engines with an old piko FZ1.
      However too high voltage could: cause spars that could damage the loco,
      melt the insulation on the windings, make the thing so hot, the plastic
      shell melts off. (the latter is not a real problem for me, since most
      of my locos have metal shells)

      > Additionally, since these newer MTL locs have a pc board inside, why
      > didn't they build in a voltage limiter circuit?

      Because that would just burn off the excess voltage as heat, and would
      also damage the loco, but in a different way. The best solution is
      to limit the track voltage. Mostly I run my locos with 6 volts maximum,
      whith a driver circuit that can output 12V when used rail to rail or
      with the new marklin dc controller (and a continous version I made)
      with a max. output of 10V and a min output of 2V (or 1V in my design).
      The max current is between 2A and 500mA, depending on the chip used,
      however going above 1A may be dangerous for the wheels in case of a
      derailment.
    • Garth Hamilton
      Mark The quick answer is your Marklin power is fine provided you do not put the power to the maximum position while running these engines. In short at 9vdc
      Message 2 of 21 , May 4, 2008
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        Mark

        The quick answer is your Marklin power is fine provided you do not
        put the power to the maximum position while running these engines. In
        short at 9vdc these engines will leave the tracks so there should be
        reason to have the power that high. The limitation on these motors is
        based on who much heat they can dissipate. So the voltage limit is
        set at 9 volts as this is the highest voltage they can be run at 75%
        duty cycle continuously. These specs will be different from motor to
        motor but that is the reason for the limit. They will operate briefly
        at higher settings but the higher you go the shorter the time they
        will survive at the higher voltage. They fail due to high heat in the
        windings which usually burns the insulation on the winding and the
        windings start to short to-gether and at that point you see the puff
        of smoke as it dies.

        The main danger with power packs that are not designed for Z-Scale is
        the current possible in a short circuit situation ie. you derail at a
        switch and the lead truck on your Pacific shorts across the rails.
        For Z-scale you can if you monitor the voltage to the track on
        straight DC use just about any power pack but you want one with a
        upper limit of 1 amp maximum and I prefer those with just half an amp
        (0.5 amp). You can still run a 3 engine MU on this type of power with
        the current crop of engines but may not be able to do so with older
        Marklin 3 pole motor types where you might only get 2 to MU as three
        trips the protection circuit. I also prefer a power pack with crow
        bar protection. 12v power packs with a 1amp rating are fine provided
        you do not run your engines at max 12vdc from the power pack. If you
        crack the throttle and monitor your track voltage with an engine on
        the track as you open the throttle you will see with many of the
        current crop of engines that they start to move at between 1.5 and 3
        vdc and the current is about .1 of an amp in fact if you want to
        monitor the current you really need a meter that is 1 amp full scale
        to be able to read these values. Most of us probably run our trains
        at 4.5 to 6 vdc max even on our flyers. I would be surprised if any
        of us run them at even 8 or 9 vdc. The problem comes when a engine
        developes a problem and we keep adding power to get to move faster
        and keep increasing the voltage until there is that inevitable puff
        of smoke and the thing quits.

        Crow Bar Protection is a circuit that detects a dead short across the
        rails or wiring and shuts down the power to the rails so you do not
        fry stuff. However it may not protect you from a motor that for some
        reason is running hot and creates an open winding and the thing quits
        on you. These sorts of power units are usually the Jorger, Thek, and
        other electronic throttles which accomplish these tasks. I also have
        some from Japan that also feature this sort of protection.

        Measuring the output of a power pack under no load conditions is not
        really a true test of the limits of a none electronic power pack as
        the circuit needs a load or and engine on the track to truly measure
        its upper limit or a low value resister.

        DCC is a whole different story. Standard DCC puts a fixed voltage on
        the rails of DC 15 to 18v and then imposes an AC signal on top of the
        DC to control the trains and the receiver in the engine determines
        what part of the track DC voltage it is going to pass on to the motor
        in the engine to make it move. As these systems are designed to run
        multiple trains the amperage of these units can be as high as 5 amps.
        So caution is needed in what you purchase. For z-scale it is
        preferred that this fixed DC voltage to the track be in the 10 to
        12vdc range so Atlas designed a diode voltage dropper circuit to drop
        the track voltage on their systems to this range for Z-scale and I
        have seen some use a variation of this on their N-scale layouts also.
        However, this does nothing to limit the current available on the
        track even at these voltages. However this can be problem with some
        decoders as they will not program properly if at all on this lower
        track voltage but they will function once programmed at these
        voltages. On DCC a short can be costly as the output current from
        most of these devices are very high as they were designed for HO and
        larger scales. So a short circuit is likely to fry something if you
        are using a standard DCC system with Z-scale. I have no experience
        with DCC on Z-scale but I do with N-scale and have seen enough fried
        wheel sets valve gear and driver wheels here to seriously pay
        attention to the special needs of Z-scale when using DCC. That is not
        to say that it is not being used successfully on Z-Scale but I have
        heard several say the learning curve is steep and can be expensive so
        if DCC is your thing and you are new to Z-scale you need to talk to
        those who have been successful with it. I know that even with N-scale
        the learning curve was steep also and costly for some.


        cheers
        Garth

        At 08:11 AM 5/4/2008, "Mark Edwards" mrex@... wrote:

        >Hi Guys, I just got my hands on those two beautiful MTL locs I
        >mentioned in my last thread, a Chessie GP35 and Santa Fe GP9. After
        >carefully reading the instructions, I noted the warning that these
        >locs use a 9 volt motor, and will burn out if run at higher voltages.
        >
        >Am I correct in assuming that I can blow these locs with my Marklin
        >67271 10 volt trafo?
        >
        >I got worried enough about this that I metered my trafo, and thank god
        >I did! While its rated at 10v, its actually putting out *15v* under
        >no load at max setting. I made a point of finding out where the 9v
        >limit was on the knob, and also metered the track while the locs were
        >running to make sure I got it right. (On my trafo, that setting is
        >"140 kph".)
        >
        >I also searched the posts on this forum and ran into cautions about 8v
        >and 9v Z motors, but nothing on actually burning out locs with Marklin
        >trafos. Are these trafos simply "hot", and users have to be careful?
        >
        >Additionally, since these newer MTL locs have a pc board inside, why
        >didn't they build in a voltage limiter circuit?
        >
        >Signed,
        >Watching the Locs go round,
        >*Nice and Slow*
        >
        >
      • Jim O'Connell
        ... the same ... I m with Loren. I think it is just shocking how I can t seem to get the electrics side of model railroading. You may want to get a hold of
        Message 3 of 21 , May 4, 2008
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          > If you don't hear from someone in the know on this forum, then pose
          the same
          > questions on Trainboard, or Z Central Station, as there are some real
          > electronic brainiacks found there.
          >
          >
          I'm with Loren. I think it is just 'shocking' how I can't seem to get
          the electrics side of model railroading. You may want to get a hold
          of "Cleantex" (Armand from Luxembourg) at Z Central Station. He seems
          to be on your wave length. Most of what he talks about is about a
          meter above my head. Cheers, Jim CCRR
        • Loren
          I envy you Jim, as Armand is 3 meters above my head....... Drowning in electronic stupidity, Loren ... From: Jim O Connell To:
          Message 4 of 21 , May 4, 2008
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            I envy you Jim, as Armand is 3 meters above my head.......

            Drowning in electronic stupidity,
            Loren

            ----- Original Message -----
            From: "Jim O'Connell" <jimo.crcmnvgtr@...>
            To: <z_scale@yahoogroups.com>
            Sent: Sunday, May 04, 2008 8:09 AM
            Subject: [Z_Scale] Re: Trafos And Voltage And Locs, Oh My!


            >> If you don't hear from someone in the know on this forum, then pose
            > the same
            >> questions on Trainboard, or Z Central Station, as there are some real
            >> electronic brainiacks found there.
            >>
            >>
            > I'm with Loren. I think it is just 'shocking' how I can't seem to get
            > the electrics side of model railroading. You may want to get a hold
            > of "Cleantex" (Armand from Luxembourg) at Z Central Station. He seems
            > to be on your wave length. Most of what he talks about is about a
            > meter above my head. Cheers, Jim CCRR
          • de Champeaux Dominique
            Myself I m owning a Marklin powerpack rated at 10 volts, but whatever the high voltage issues I don t use it anymore as starting voltage is far too high, and
            Message 5 of 21 , May 4, 2008
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              Myself I'm owning a Marklin powerpack rated at 10
              volts, but whatever the high voltage issues I don't
              use it anymore as starting voltage is far too high,
              and when you open the throttle only lightly you have a
              dragster-like start up.....Myself I stick to a
              Passmann powerpack.

              Dom




              --- Mark Edwards <mrex@...> a écrit :

              > Hi Guys, I just got my hands on those two beautiful
              > MTL locs I
              > mentioned in my last thread, a Chessie GP35 and
              > Santa Fe GP9. After
              > carefully reading the instructions, I noted the
              > warning that these
              > locs use a 9 volt motor, and will burn out if run at
              > higher voltages.
              >
              > Am I correct in assuming that I can blow these locs
              > with my Marklin
              > 67271 10 volt trafo?
              >
              > I got worried enough about this that I metered my
              > trafo, and thank god
              > I did! While its rated at 10v, its actually putting
              > out *15v* under
              > no load at max setting. I made a point of finding
              > out where the 9v
              > limit was on the knob, and also metered the track
              > while the locs were
              > running to make sure I got it right. (On my trafo,
              > that setting is
              > "140 kph".)
              >
              > I also searched the posts on this forum and ran into
              > cautions about 8v
              > and 9v Z motors, but nothing on actually burning out
              > locs with Marklin
              > trafos. Are these trafos simply "hot", and users
              > have to be careful?
              >
              > Additionally, since these newer MTL locs have a pc
              > board inside, why
              > didn't they build in a voltage limiter circuit?
              >
              > Signed,
              > Watching the Locs go round,
              > *Nice and Slow*
              >
              >
              >


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            • Glen Chenier
              ... ... In ... be ... What Garth says, good info. As the 67271 is intended for Z scale, it should have no higher voltage pulses (such as for HO
              Message 6 of 21 , May 4, 2008
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                --- In z_scale@yahoogroups.com, Garth Hamilton <garthah@...> wrote:
                >
                > Mark
                <snip>
                > The quick answer is your Marklin power is fine provided you do not
                > put the power to the maximum position while running these engines.
                In
                > short at 9vdc these engines will leave the tracks so there should
                be
                > reason to have the power that high.
                <snip>

                What Garth says, good info. As the 67271 is intended for Z scale, it
                should have no higher voltage pulses (such as for HO scale use) that
                can be Z motor killers.

                If the 67271 has no 'benign' pulses either (is pure DC) a DC meter
                will be accurate. Different makes and models of power packs have
                very different output waveforms, for example a MRC 1300 with every
                2nd sine pulse chopped reads 4.6 volts on a typical non-RMS DVM but
                the actual heating (RMS) value is 6.3 volts.

                In <http://groups.yahoo.com/group/Z_Scale_Electronics> message #20
                from 2 years ago by the late Bill K mentions something about a pulse
                mode of the 67271 which could make meter readings innacurate.
                Quote:
                "I found a "deal" today on a Marklin 67271 power pack and jumped on
                it. I've been wanting to find an affordable Marklin pack for some
                time, ever since Rob Kluz indicated there is a "jump" in the output
                as it switches from "some kind of pulse" to "some kind of pure DC"
                mode. I don't have a clue what that means, but I'm sure to "see"
                what "pulse" "DC" and "jump" mean on the O-scope." -Bill K.


                > At 08:11 AM 5/4/2008, "Mark Edwards" mrex@... wrote:
                <snip>
                > >Additionally, since these newer MTL locs have a pc board inside,
                why
                > >didn't they build in a voltage limiter circuit?

                Probably because a built-in voltage regulator would get hot when it
                limits a too-high voltage and could melt the shell.


                Your best approach is to feel the locos periodically to ensure they
                are not getting too hot at a particular throttle setting. Warm is
                normal, hot is not. At prototypical running speed a power pack
                designed for Z scale is safe. The dangerous power packs that ouput
                PWM square pulses of 15-20 volts or more can make a Z scale
                locomotive run very slow, but will easily burn up a Z motor at slow
                speed.

                This is discussed in the Z_Scale_Electronics forum Files along with
                oscilloscope photos of the output waveforms of various types of power
                packs. Unfortunately no 67271 waveforms there yet. Have recently
                added photos of the Zthek controller waveforms to visually show PWM
                (pulse-width-modulation) at safe voltages for Z Scale motors and how
                it does speed control. For inquiring minds pictures are worth
                thousands of words.
              • Mark Edwards
                ... bow to ... Loren, I love you man! Well spoken, roflmao. :) Don t worry, voltages differences will be worked out, and hopefully no 9v core motors will be
                Message 7 of 21 , May 4, 2008
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                  >I can do certain things well, some things fairly well, and a few things
                  >really poorly, but when it comes to electronics, I plead the 5th.
                  >You lost me way back about Central Station/Command Center. I humbly
                  bow to
                  >the folks who not only talk this aspect of the hobby, but actually
                  >understand it and can work with it.
                  >As I said once before, I am happy to just see the wheels stay on the
                  >track......anything more and I figure I'm tempting fate.

                  Loren, I love you man! Well spoken, roflmao. :)

                  Don't worry, voltages differences will be worked out, and hopefully no
                  9v core motors will be harmed as a result. There may be some bashing
                  of the locs however, debugging these computer layouts can cause some
                  trouble:

                  http://www.vespasnyc.com/images/crash.MOV

                  Again, its a curse I live under. I could be a plumber, or a garbage
                  man, but *NOOOO* I had to be a Software Engineer!

                  :)
                • Thomas Creighton Sr
                  the web address list below does not work? Mark Edwards wrote: I can do certain things well, some things fairly well, and a few
                  Message 8 of 21 , May 4, 2008
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                    the web address list below does not work?

                    Mark Edwards <mrex@...> wrote: >I can do certain things well, some things fairly well, and a few things
                    >really poorly, but when it comes to electronics, I plead the 5th.
                    >You lost me way back about Central Station/Command Center. I humbly
                    bow to
                    >the folks who not only talk this aspect of the hobby, but actually
                    >understand it and can work with it.
                    >As I said once before, I am happy to just see the wheels stay on the
                    >track......anything more and I figure I'm tempting fate.

                    Loren, I love you man! Well spoken, roflmao. :)

                    Don't worry, voltages differences will be worked out, and hopefully no
                    9v core motors will be harmed as a result. There may be some bashing
                    of the locs however, debugging these computer layouts can cause some
                    trouble:

                    http://www.vespasnyc.com/images/crash.MOV

                    Again, its a curse I live under. I could be a plumber, or a garbage
                    man, but *NOOOO* I had to be a Software Engineer!

                    :)






                    [Non-text portions of this message have been removed]
                  • Mark Edwards
                    Very Interesting! Thanks everyone for the replies! I m not really sure what to make of it all, but there s some really good advice about power, locs getting
                    Message 9 of 21 , May 4, 2008
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                      Very Interesting!

                      Thanks everyone for the replies! I'm not really sure what to make of
                      it all, but there's some really good advice about power, locs getting
                      hot, and Z loc performance here.

                      Some points I should make to everyone, whether they are "electrically
                      challanged" or not:

                      1 -- I will limit both current and voltage to the track. I will make
                      sure that short circuit detection is in place, and fast. I will do my
                      best to trip a breaker or blow a fuse and shut down track power
                      instead of frying a solenoid, or worse yet, a loc decoder or motor.

                      2 -- I know that traditional DCC solutions are designed for higher
                      power consumers, and Z gauge is the lowest of the power consumers in
                      the Railroad biz right now. Almost any "off the shelf" DCC setup
                      (like the Super Cheif) can fry my stuff in a second if I'm not carefull.

                      3 -- I point out that under DCC, the track is supplied with AC (in the
                      form of a complicated computer generated wave), and that therefore
                      maximum voltages are taken as the RMS of the voltages, and DC
                      measurements make no sense or are misleading.

                      4 -- I now think that Marklin trafo's run "hot", and that Marklin 5
                      pole motors are designed *not* for low speed performance, but meduim
                      to high speed running stability.

                      (Again, that Mikado needs servicing, it might overcome low voltage
                      stalls and show improved low speed performance if it were properly
                      cleaned and oiled.)

                      I also think the trafo's 2.5v starting point is too high, I'd love to
                      see what these MTL's can do with 1 volt. These MTL's can creep at 2.5
                      volts for ever. That is simply beautiful to my thinking, and I love it.

                      Okay, that's enough for now, but thanks again for the replies, and
                      I've read every word. I'll keep you posted...

                      Signed,
                      Watching The Chessie Creep
                    • Alan Cox
                      ... Good DCC stuf has fast acting short circuit protection as the AC circuit power is quite high usually (2.5-5A) which is enough to do damage to much bigger
                      Message 10 of 21 , May 5, 2008
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                        > 2 -- I know that traditional DCC solutions are designed for higher
                        > power consumers, and Z gauge is the lowest of the power consumers in
                        > the Railroad biz right now. Almost any "off the shelf" DCC setup
                        > (like the Super Cheif) can fry my stuff in a second if I'm not carefull.

                        Good DCC stuf has fast acting short circuit protection as the AC circuit
                        power is quite high usually (2.5-5A) which is enough to do damage to much
                        bigger models if for example the two trucks ended up either side of a
                        reversing loop shorting through the model.

                        Good ones also let you turn the voltage down - dropping them to 12v or so
                        for N and Z scale can significantly drop heat production in the decoders.

                        > 3 -- I point out that under DCC, the track is supplied with AC (in the
                        > form of a complicated computer generated wave), and that therefore
                        > maximum voltages are taken as the RMS of the voltages, and DC
                        > measurements make no sense or are misleading.

                        It depends if you want to measure peak voltage (for breakdown etc) or RMS
                        for things like heat: RMS is also only valid for a sine wave which DCC is
                        most definitely *not*.

                        > I also think the trafo's 2.5v starting point is too high, I'd love to

                        Agreed but you can fix that. Wire pairs of back to back diodes between
                        the DC controller and the track and each pair will drop 0.7v or so which
                        means two pairs of diodes will take you down to 1.1v base.

                        You need ones that'll take the power level - which isn't much for Z but
                        they cost peanuts anyway.

                        Alan
                      • Allan Borg
                        Contrary to a prevous statment DCC does not have any DC voltage component applied to the track it is a constantly switching square wave with a peak to peak
                        Message 11 of 21 , May 5, 2008
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                          Contrary to a prevous statment DCC does not have any DC voltage
                          component applied to the track it is a constantly switching square
                          wave with a peak to peak voltage adjustable from 15 to 18 volts.
                          In terms of DC power supplies, which I worked in the industry
                          designing and building, crowbar circuits were an add-on device that
                          would measure the output voltage and switch on a SCR effectivly
                          shorting out the output terminals if the voltage went too high (hence
                          crowbar).
                          The power supply itself had a current foldback circuit that
                          reduces the output current and voltage if any short was detected.
                          The unfortunate thing about regulator components like the LM 317
                          voltage regulator, they still put out some current and voltage. That
                          is evidenced by one of my club's MT F7's stalling across the
                          crossover track and melting the plastic front truck.
                          The best power controller I have experience using is the dual
                          controller from MRC which had outputs from 0 to 10.8 volts. The dials
                          calibrated almost directly as voltage applied to the track. These
                          power packs also have a short limit breaker that removes power from
                          the track until the short is elimnated. Unfortunately these
                          controllers are no longer made with the voltage range in the newer
                          models.
                          Allan Borg
                          --- In z_scale@yahoogroups.com, Alan Cox <alan@...> wrote:
                          >
                          > > 2 -- I know that traditional DCC solutions are designed for higher
                          > > power consumers, and Z gauge is the lowest of the power consumers
                          in
                          > > the Railroad biz right now. Almost any "off the shelf" DCC setup
                          > > (like the Super Cheif) can fry my stuff in a second if I'm not
                          carefull.
                          >
                          > Good DCC stuf has fast acting short circuit protection as the AC
                          circuit
                          > power is quite high usually (2.5-5A) which is enough to do damage
                          to much
                          > bigger models if for example the two trucks ended up either side of
                          a
                          > reversing loop shorting through the model.
                          >
                          > Good ones also let you turn the voltage down - dropping them to 12v
                          or so
                          > for N and Z scale can significantly drop heat production in the
                          decoders.
                          >
                          > > 3 -- I point out that under DCC, the track is supplied with AC
                          (in the
                          > > form of a complicated computer generated wave), and that therefore
                          > > maximum voltages are taken as the RMS of the voltages, and DC
                          > > measurements make no sense or are misleading.
                          >
                          > It depends if you want to measure peak voltage (for breakdown etc)
                          or RMS
                          > for things like heat: RMS is also only valid for a sine wave which
                          DCC is
                          > most definitely *not*.
                          >
                          > > I also think the trafo's 2.5v starting point is too high, I'd
                          love to
                          >
                          > Agreed but you can fix that. Wire pairs of back to back diodes
                          between
                          > the DC controller and the track and each pair will drop 0.7v or so
                          which
                          > means two pairs of diodes will take you down to 1.1v base.
                          >
                          > You need ones that'll take the power level - which isn't much for Z
                          but
                          > they cost peanuts anyway.
                          >
                          > Alan
                          >
                        • Garth Hamilton
                          Mark If you want some incite into DCC for small scales you might want to read the article in the magazine N-Scale Railroading for May/June 2008 and the article
                          Message 12 of 21 , May 5, 2008
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                            Mark

                            If you want some incite into DCC for small scales you might want to
                            read the article in the magazine N-Scale Railroading for May/June
                            2008 and the article part six of The Spokane International Railway on
                            Wiring and Controls as it all about DCC and computer control.

                            N-scale Railroading back issues can be found here if not found in your LHS
                            http://www.nscalerailroadn.com/Backissues.html

                            Not associated just a reader

                            regards
                            Garth


                            At 08:37 AM 5/5/2008, "Mark Edwards" mrex@... wrote:

                            >Very Interesting!
                            >
                            >Thanks everyone for the replies! I'm not really sure what to make of
                            >it all, but there's some really good advice about power, locs getting
                            >hot, and Z loc performance here.
                            >
                            >Some points I should make to everyone, whether they are "electrically
                            >challanged" or not:
                            >
                            >1 -- I will limit both current and voltage to the track. I will make
                            >sure that short circuit detection is in place, and fast. I will do my
                            >best to trip a breaker or blow a fuse and shut down track power
                            >instead of frying a solenoid, or worse yet, a loc decoder or motor.
                            >
                            >2 -- I know that traditional DCC solutions are designed for higher
                            >power consumers, and Z gauge is the lowest of the power consumers in
                            >the Railroad biz right now. Almost any "off the shelf" DCC setup
                            >(like the Super Cheif) can fry my stuff in a second if I'm not carefull.
                            >
                            >3 -- I point out that under DCC, the track is supplied with AC (in the
                            >form of a complicated computer generated wave), and that therefore
                            >maximum voltages are taken as the RMS of the voltages, and DC
                            >measurements make no sense or are misleading.
                            >
                            >4 -- I now think that Marklin trafo's run "hot", and that Marklin 5
                            >pole motors are designed *not* for low speed performance, but meduim
                            >to high speed running stability.
                            >
                            >(Again, that Mikado needs servicing, it might overcome low voltage
                            >stalls and show improved low speed performance if it were properly
                            >cleaned and oiled.)
                            >
                            >I also think the trafo's 2.5v starting point is too high, I'd love to
                            >see what these MTL's can do with 1 volt. These MTL's can creep at 2.5
                            >volts for ever. That is simply beautiful to my thinking, and I love it.
                            >
                            >Okay, that's enough for now, but thanks again for the replies, and
                            >I've read every word. I'll keep you posted...
                            >
                            >Signed,
                            >Watching The Chessie Creep
                          • Jeff BAZ-man
                            Mark, not to worry. All good points but here is a brief summary: Motors are not like semiconductors. They can take much higher voltage on a transient basis.
                            Message 13 of 21 , May 5, 2008
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                              Mark, not to worry. All good points but here is a brief summary:

                              Motors are not like semiconductors. They can take much higher
                              voltage on a transient basis. The motor voltage rating is more
                              targeted at continuous voltage as that relates directly to power.

                              Examples of this: DCC runs 15-18V track voltage for most systems.
                              Rectified and motor driver losses are about 1-2 volts so variable
                              duty cycles pulse that control the speed of the motor are ~~12-15V.
                              But they tend to be 10-30% duty cycle [ on to off ratio] or the
                              loco would run like a rocket. They have survived this way for a
                              very long time. Note: the Z scale recommended DCC voltage is 10.
                              Most Boosters will adjust this low. At least set them to 12 or
                              12.75 like NCE's Power Cab is out-of-the-box.

                              Another EXTREME is example is the Relco Gauge Master track cleaner.
                              This very high frequency generator produces up to 400 volts, peak-to-
                              peak when there is nothing on the track. As soon as the loco makes
                              contact, the voltage drops to near zero. But if you watch the track
                              voltage in action, it is all over the place as the wheels make
                              intermittant pickup. So the motor is goign to see voltage somewhat
                              higher than 8v (not the full 400 !! but definitely above 8) as it
                              connects and disconnects from the track.

                              ANY Märklin loco will run a VERY unprototypical speed to 9V. 3-6 is
                              more common for high speed running. (60 scale MPH = 48" in 10
                              seconds [ a 4' module] ) if I did my match correctly.

                              Märklin locos were designed to run 5 or so car trains, like you see
                              in the catalogs. If you try and pull 20 car trains or worse, on a
                              grade, you will need more power. More power means more voltage and
                              heat.

                              Märklin made the power packs to run their trains. They have been
                              doing so for 30+ years. Enjoy running your trains. Just don't run
                              20 car trains up grades, unless you use several locos.


                              Jeff
                              SF Bay Area Z
                              --- In z_scale@yahoogroups.com, "Allan Borg" <themohican2003@...>
                              wrote:
                              >
                              > Contrary to a prevous statment DCC does not have any DC voltage
                              > component applied to the track it is a constantly switching square
                              > wave with a peak to peak voltage adjustable from 15 to 18 volts.
                              > In terms of DC power supplies, which I worked in the industry
                              > designing and building, crowbar circuits were an add-on device
                              that
                              > would measure the output voltage and switch on a SCR effectivly
                              > shorting out the output terminals if the voltage went too high
                              (hence
                              > crowbar).
                              > The power supply itself had a current foldback circuit that
                              > reduces the output current and voltage if any short was detected.
                              > The unfortunate thing about regulator components like the LM 317
                              > voltage regulator, they still put out some current and voltage.
                              That
                              > is evidenced by one of my club's MT F7's stalling across the
                              > crossover track and melting the plastic front truck.
                              > The best power controller I have experience using is the dual
                              > controller from MRC which had outputs from 0 to 10.8 volts. The
                              dials
                              > calibrated almost directly as voltage applied to the track. These
                              > power packs also have a short limit breaker that removes power
                              from
                              > the track until the short is elimnated. Unfortunately these
                              > controllers are no longer made with the voltage range in the newer
                              > models.
                              > Allan Borg
                              > --- In z_scale@yahoogroups.com, Alan Cox <alan@> wrote:
                              > >
                              > > > 2 -- I know that traditional DCC solutions are designed for
                              higher
                              > > > power consumers, and Z gauge is the lowest of the power
                              consumers
                              > in
                              > > > the Railroad biz right now. Almost any "off the shelf" DCC
                              setup
                              > > > (like the Super Cheif) can fry my stuff in a second if I'm not
                              > carefull.
                              > >
                              > > Good DCC stuf has fast acting short circuit protection as the AC
                              > circuit
                              > > power is quite high usually (2.5-5A) which is enough to do
                              damage
                              > to much
                              > > bigger models if for example the two trucks ended up either side
                              of
                              > a
                              > > reversing loop shorting through the model.
                              > >
                              > > Good ones also let you turn the voltage down - dropping them to
                              12v
                              > or so
                              > > for N and Z scale can significantly drop heat production in the
                              > decoders.
                              > >
                              > > > 3 -- I point out that under DCC, the track is supplied with AC
                              > (in the
                              > > > form of a complicated computer generated wave), and that
                              therefore
                              > > > maximum voltages are taken as the RMS of the voltages, and DC
                              > > > measurements make no sense or are misleading.
                              > >
                              > > It depends if you want to measure peak voltage (for breakdown
                              etc)
                              > or RMS
                              > > for things like heat: RMS is also only valid for a sine wave
                              which
                              > DCC is
                              > > most definitely *not*.
                              > >
                              > > > I also think the trafo's 2.5v starting point is too high, I'd
                              > love to
                              > >
                              > > Agreed but you can fix that. Wire pairs of back to back diodes
                              > between
                              > > the DC controller and the track and each pair will drop 0.7v or
                              so
                              > which
                              > > means two pairs of diodes will take you down to 1.1v base.
                              > >
                              > > You need ones that'll take the power level - which isn't much
                              for Z
                              > but
                              > > they cost peanuts anyway.
                              > >
                              > > Alan
                              > >
                              >
                            • Mark Edwards
                              Wow, You guys. I love you all. Melting trucks when a loc shorts on a turnout? Its okay as long as I don t turn up the power pack? ***400 volts*** from a
                              Message 14 of 21 , May 5, 2008
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                                Wow,

                                You guys. I love you all. Melting trucks when a loc shorts on a
                                turnout? Its okay as long as I don't turn up the power pack? ***400
                                volts*** from a Relco Gauge Master Track Cleaner?

                                I WANT MY MOMMY! :)

                                Your replies are invaluable, and at the very least I'm adding into the
                                knowledge base that is the post archive for this group. At the very
                                best, I ain't burnt no locs yet! *YET!*

                                And I don't intend to. Post first, burn never, if I can help it...

                                I should point out that I've run some DCC/Motorola layouts in HO,
                                using both Marklin stuff and the Digitrax Super Chief. I've also
                                bothered the guys over at the Marklin Bar & Grill with this stuff for
                                a year now, and the number of posts is comparable.

                                I have noted all of this, and will post again when I have the decoders
                                and the track ready for true DCC. For now, I'm keeping that Marklin
                                trafo on the DL...

                                -- Manhattan Z Guy

                                P.S. I want a Relco Guage Master Track Cleaner, for my home-made Van
                                DeGraff Generator. Think I can get some sparks from that? ;)
                              • Alan Cox
                                ... Heat is from power not voltage. Keep the current down and the world is a happy place. ... 400V at uamps - don t mix it with DCC (or decoder fitted locos
                                Message 15 of 21 , May 6, 2008
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                                  > You guys. I love you all. Melting trucks when a loc shorts on a
                                  > turnout? Its okay as long as I don't turn up the power pack? ***400

                                  Heat is from power not voltage. Keep the current down and the world is a
                                  happy place.

                                  > volts*** from a Relco Gauge Master Track Cleaner?

                                  400V at uamps - don't mix it with DCC (or decoder fitted locos either)
                                  but for DC it's not going to set your trucks on fire. On the other hand
                                  its an excellent cat and small child repellant as you can get quite a
                                  sting from a track with a relco on it.

                                  Alan
                                • Jeff BAZ-man
                                  True, power is the direct heat factor but still directly proportional to voltage or current increases. I was surprised to hear that the later Märklin power
                                  Message 16 of 21 , May 6, 2008
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                                    True, power is the direct heat factor but still directly
                                    proportional to voltage or current increases. I was surprised to
                                    hear that the later Märklin power packs are solid state regulted
                                    with a LM317 instead of the variable tap transformer of so many
                                    years past. I can understand the LM317 in the 9V battery controller
                                    but not the 120/220 AC power pack. Interesting, will have to look
                                    at that. The LM317 will regulate voltage up to the current limit,
                                    3A, but at that point it will foldback the voltage as low as 0.5V so
                                    only 1.5W. That might be enough to melt a truck. The AC power
                                    packs are self limiting but still can deliver at least the same
                                    amount of power.

                                    With ANY power pack or especially with DCC, WATCH YOUR LOCOS !!!
                                    Especially if you have turnouts !!!

                                    I didn't mention the extremely low current of the Relco Gauge
                                    Master. Enough to tingle or be painful with a wet human body part
                                    but not enough to be dangerous. The subject was the voltage limit
                                    of the motors which I wanted to de-emphasize as we all run them well
                                    beyond their limits on a daily basis.

                                    One thing that truly surprises me is why the 50V rated ceramic disc
                                    capacitors used in the Märklin locos for noise surpression don't
                                    eventually fail with the Gauge Masters. Sooner or later, they
                                    should suffer from punch through but again, we all run them days on
                                    end with no issues. Most of us either run out of lube (or dried out
                                    much faster than expected from heat), have brush/armature issues or,
                                    the fried truck issue (especially on the much higher power DCC).

                                    Jeff
                                    SF Bay Area Z

                                    --- In z_scale@yahoogroups.com, Alan Cox <alan@...> wrote:
                                    >
                                    > > You guys. I love you all. Melting trucks when a loc shorts on a
                                    > > turnout? Its okay as long as I don't turn up the power pack?
                                    ***400
                                    >
                                    > Heat is from power not voltage. Keep the current down and the
                                    world is a
                                    > happy place.
                                    >
                                    > > volts*** from a Relco Gauge Master Track Cleaner?
                                    >
                                    > 400V at uamps - don't mix it with DCC (or decoder fitted locos
                                    either)
                                    > but for DC it's not going to set your trucks on fire. On the other
                                    hand
                                    > its an excellent cat and small child repellant as you can get
                                    quite a
                                    > sting from a track with a relco on it.
                                    >
                                    > Alan
                                    >
                                  • viktor_kovacs
                                    ... You can get LM317-s with various max currents, even as low as 250mA. I think marklin uses 1-1.5A ones. The ac power pack comes in this form, because it s
                                    Message 17 of 21 , May 7, 2008
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                                      --- In z_scale@yahoogroups.com, "Jeff BAZ-man" <sjbazman49@...>
                                      > True, power is the direct heat factor but still directly
                                      > proportional to voltage or current increases. I was surprised to
                                      > hear that the later Märklin power packs are solid state regulted
                                      > with a LM317 instead of the variable tap transformer of so many
                                      > years past. I can understand the LM317 in the 9V battery
                                      > controller but not the 120/220 AC power pack. Interesting,
                                      > will have to look at that.
                                      > The LM317 will regulate voltage up to the current limit,
                                      > 3A, but at that point it will foldback the voltage as low as
                                      > 0.5V so only 1.5W.
                                      > That might be enough to melt a truck. The AC power
                                      > packs are self limiting but still can deliver at least the same
                                      > amount of power.

                                      You can get LM317-s with various max currents, even as low as 250mA.
                                      I think marklin uses 1-1.5A ones. The ac power pack comes in this
                                      form, because it's cheap and you can use the same controller and
                                      only swap the power bricks. For a big layout, you can even use
                                      one big power pack (like an atx power supply) and power all
                                      controllers from the same source. The circuit could be reused for
                                      battery controllers or connected to a dc only car charger. Not
                                      to mention it's very very cheap with a cheap pulse mode brick
                                      when compared to a real trafo. Also it comes with built-in
                                      input/output short circuit protection. And it's light too.
                                      In the recent years, marklin tried to reduce costs and using
                                      a simple and cheap circuit works very well for this purpose.

                                      I made a copy of their circuit with a very fine continous pot
                                      and with dptt switch based direction selection and the whole
                                      circuit came out around 4 dollars including the box. The bigger
                                      3A version went to a friend of mine with a big DC H0 layout and
                                      the 500mA version was for me.

                                      > With ANY power pack or especially with DCC, WATCH YOUR LOCOS !!!
                                      > Especially if you have turnouts !!!

                                      Or use very sensitive overcurrent protection. The marklin solid
                                      state power pack doesn't really care if I accidentally put a loco
                                      on the tracks the wrong way and make a short through the wheels.
                                      At least it didn't melt my old br89. (it's my track test loco,
                                      if the 0-6-0 steamer runs anything runs, especially that my old
                                      8800 variant has only 2x2 wheel power pickups)

                                      > I didn't mention the extremely low current of the Relco Gauge
                                      > Master. Enough to tingle or be painful with a wet human body
                                      > part but not enough to be dangerous. The subject was the
                                      > voltage limit of the motors which I wanted to de-emphasize
                                      > as we all run them well beyond their limits on a daily basis.

                                      The relco is not really dangerous, unless you have led lighting.
                                      Some versions of led lights are extremly sensitive to overvoltage.
                                      If you put some load on the tracks, the high voltage gets burned
                                      off as very low current. (actually it's a very low current ac
                                      source converted to high voltage by a mixing transformer)

                                      > One thing that truly surprises me is why the 50V rated ceramic
                                      > disc capacitors used in the Märklin locos for noise surpression
                                      > don't eventually fail with the Gauge Masters. Sooner or later,
                                      > they should suffer from punch through but again, we all run them
                                      > days on end with no issues. Most of us either run out of lube
                                      > (or dried out much faster than expected from heat), have brush/
                                      > armature issues or, the fried truck issue (especially on the much
                                      > higher power DCC).

                                      The idea is that when the railco goes to a higher voltage, the disc
                                      capacitor is either disconnected or discharged. The overvoltage is
                                      really dangerous for a fully charged capacitor. Besides that, if
                                      they fail with a break instead of a short, you don't really notice
                                      it at all. For dcc, you should remove the little disk anyway and
                                      besides that, you can go as low as 9V with dcc. (if you can fit the
                                      decoder into the loco in the first place)

                                      Viktor
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