.. where I am confused …for a while (short story)

[ Jan 2018 ] My buddy Gary Wise came by earlier as his wife Linda was doing that ‘shopping thing’ and he needed a place to go, so we hung out a bit and discovered that there was a dead .. and I mean DEAD piece of track on my main. “HUH!” .. I said ….

Now .. while I may sometimes call myself a Model Railroader .. I am really more of a Modeler. That helps explain why as I told Gary – “I haven’t run a train in six months ..”. This got me a stern look while I looked under the layout to try and see .. why .. that piece of track was so totally dead. I could see the feeder wire … which .. hung loose. Huh says .. I .. that may partially explain the dead track .. I suppose the rail joiner COULD be really corroded .. then .. wait .. another feeder wire hanging loose. Huh again.

I swear .. sometimes the light over my head is a very dim one .. and it flickers a lot. I remembered that I had diagrammed the electrical on my layout so I rummaged around my hard drive and found it .. and … Oh … I had isolated two sections of track on either side of what will/would be the programming track. I did all the isolating, wiring and was waiting for the 4PDT switches to come .. and completely forgot about it.

Yes .. poor little flickering light. Look .. I think it is dimming even more.


For anyone that may land on this page .. I am working on it. If you see this notice then take what is below with a grain of salt (as they say) as it will be incorrect, incomplete or both.

4PDT Switch

In the following I will be referring to the 4PDT switches with the lug numbering as shown – looking from the lug side of the switch. Lugs are connected as follows:

Fig 1
  • Switch thrown up/top : [2/3] [5/6] [8/9] [11/12]
  • Switch thrown down/bottom : [1/2] [4/5] [7/8] [10/11]

A Note Regarding Switches
The best choice of a 4PDT switch for your program track is a Center-Off version. This ensures that one circuit is completely disconnected prior to the new connection being established.

Switches are available as “make before break” and “break before make”. For this application, a “break before make” is essential, and a center-off version is the easiest way to make sure the switch breaks before making a connection. This avoids the possibility of momentary connecting the booster output to the programming track output terminals.

Programming Track

On the www.dccwiki.com website the page Programming Track provided everything I needed to create one on my layout. I’m not going to go crazy on the details here as it is put very well in the link. I will though post the bit at the very start of the article:

Fig 2

A programming track is used to program decoders. For mobile decoders, it’s easiest to have a portion of your layout track to double as a programming track. …  For greater flexibility the track should be part of the layout trackage. The reason for this is to minimize handling of finely detailed locos on your layout and allows you to simply drive your loco to the programming section, and read/change values of the decoder.

To prevent a locomotive from accidentally shorting the program track you need a section of track as shown below. The programming section needs to be at least 50% longer than your longest locomotive and the isolating section must be longer than your longest locomotive too. The longer the programming track is the more useful it will be.

Finally .. to the wiring. A diagram is presented – Fig 1. I will start with this .. and “do my own thing”.

MRC Prodigy Advance2

Fig 3

I was confused for a bit by “From Booster” and “From Command Station“. Hey .. sometimes I a slow like that. Looking closer at Fig 3 from the MRC Prodigy Advance2 User’s Manuel and Fig 2 I finally “got it“.

From Booster” means for my Prodigy Advance2 the “To Main Track” and “From Command Station” the “To Program Track“.

*sigh* .. said I was slow.

I will change the labeling to reflect “Main Track” and “Program Track” on my Prodigy Command Station (Base Unit)

my Programming Track wiring

The wiring diagram is a … work in progress .. at best. It needs to be re-drawn and the LED circuit completely rethought .. need powering via the accessory side of the DC throttle box, switched via .. transistors I think.

Fig. 4

The position of SW1 will either feed DC or DCC. The idea being the ability to test both a DC and a DCC loco.

  • SW1 Up – DC from the DC Throttle via lugs SW1[9][12] to lugs SW1[8][11] is fed to lugs of the second switch – SW2[8][11]
  • SW1 Down – DCC (Command Station – Main Track) via lugs SW1[7][10] to lugs SW1[8][11] is fed to the input of the second switch SW2[8][11]

Depending on which way SW2 is thrown, either the Test Track and Isolation sections are DCC/DC powered or the Test Track is powered and the Isolation sections without any power.

  • SW2 Up – Switch-ology adds the Isolation Track and the Test Track (Program) back into the layout with either DC or DCC power.
    • DC or DCC power from SW1[8][11] feeds SW2[8][11] which feeds SW2[9][12] which powers the Isolation Track with DC from the DC Throttle or DCC from Main Track.
    • DC or DCC power from SW1[8][11] feeds SW2[3][6] which feeds SW2[9][12]which powers the Test Track (Program) with DC from the DC Throttle or DCC from Main Track.
  • SW2 Down – routes Program Track power to the Test Track (Program) and removes any power from the Isolation Track.
    • Program Track lugs on the Command Station feeds power to SW2[1][4] which feeds SW2[2][5] which feeds the Test Track (Program).
    • Isolation Track is totally disconnected from power.

Test/Program track LED

DC or DCC power from SW1[8][11 feeds SW2[8][11] which feeds SW2[7][10] which powers the LED. The LED is optional and may or may not work depending on the DCC system used. Some DCC systems will shutdown the main line when programming is active leaving the LED unpowered. A little research shows me that a simple “Wall Wart” – power adapter putting out 12V at 3A would be the way to go. I simply need to use a PNP LED circuit.

Fig. 5

Notes: This is a LED driver circuit using a PNP transistor to control a LED. When power is removed from the transistor base the LED lights. In this case power to the Isolation track is removed. My calculatins:

  • LED – Panel LED.- such as a Radio Shack No. 2760068 4mm LED with holder. This has a Typical voltage of 2.3V – Max voltage of 2.8V with 20mA current.
  • Q1 – PNP transistor – 2N3906
  • R1 – 34K
  • R2 – 135 ohm
  • V – 5V Wall Wart)
  • Control – this would be voltage to the Isolation track since when SW2 is thrown up to connect the Program Track and the Test Track (Program) power is cut to the Isolation track .. call it .. 14V.



Fig. 6
  • My thoughts on this run something like .. such wiring not what I want to do under the bench-work. I think that everything .. panel, switches, terminal strips etc. needs to be contained in a separate assembly that can be built and wired on a work bench and then after screwed to the layout fascia.
  • The current plan is to mount the Barrier Strips with wiring in a project box. A separate control panel will mount the Switches and LEDs. Cables will connect the two.
  • BS12-1 .. This Barrier Strip has all the connections for D-Sub D1 on the left. D1 itself is imagined to be mounted somewhere on the project box. The wiring between the D1 Barrier Strip side and D1 should be relatively neat. From D1 a bundled cable will go to SW1 (4PDT switch). Much the same for BS12-2 with all the D2 connectors on the right side. In the same fashion, a bundled cable runs from D-Sub 2 to SW2.

Exterior to the Project Box are ..

  • Command Station : Main Track and Program Track connectors are screw terminal. Makes little sense to have to lose wires to the project box .. would make sense to combine them into one (bundled) cable
  • DC Throttle connectors are screw terminals .. so one wire . .maybe
  • Test Track and Isolating Track .. feeders from track need to connect to a more substantial wire
  • Seems to me that instead of a bunch of loose dangling wires running to the project box it would make sense to run those wires to a single box and have a single bundled cable from that box to the project box…. see Fig. 7 to the left. The gray terminal strip would be attached to a small project box with a DE-9S for a DE-9 M/M cable connection.

Panel Test Build

Fig. 8

Jumped to making the panel (control panel .. just a Mock Up (this was a while back). I picked up a small, cheap photo frame at Walmart, and 0.080″ Acrylic sheet at Lowes and a printed piece of cardstock .. all sandwiched together and a small box built around it. Here, I am test fitting it by loosely mounting. I need to mount the electrical panel underneath and then I can get a good measure of how long my cabling needs to be.

  • Main (Booster) Power – change that to Main Track Power
  • Programming/Test Track .. change that to Programming Track
  • Program Track Power (DCC) supposed to show that Main Track Power is being supplied.
  • Test Track Power (DC) .. again .. the Program Track/Test Track is supposed to indicate it has DC power to it
  • Isolation Track .. needs like to indicate whether is isolated or not
  • The toggle switches are supposed  sit between the options .. top switch chooses between Main and Program Track and the bottom switch chooses either DCC or DC. Needs to be made clear someway.


Something like this imaginary scenerio/panel

  • Power: Toggle switch to DCC .. so power from Main Track and the LED turns green. If the toggle were flipped to DC then that would turn green and the DCC LED would go red. The toggle and indicators only show that either DC or DCC is available. Whether they are used or not depends on the other switch
  • Program Track: The Program track can either be part of the layout .. switch flipped to DC/DCC or route the signal from the Command Station Program section. In this example the DC/DCC .. or power to the Program track has been selected. DCC was selected above
  • Isolation track: The Isolation track on either side of the Program Track is longer than the longest loco to prevent said loco to prevent accidental shorting of the Program Track. In this example the Isolation Track .. isn’t as it is a powered part of the alyout as is the Program Track. This is indicated by the LEDs.
  • Lighting Controls: I think this panel would be a good place to control the lighting on the layout .. at least as far as lighting for buildings, streetlights and such is concerned. Controlling the actual layout lighting (day vrs night) might be a bit much
    • An on/off switch. Could be a toggle, push button etc to power on/off all the lighting
    • A rheostat – for overal lights
    • Separate switch and rheostat for buildings
    • Separate switch and rheostat for streetlights etc.
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gary wise

mine dont i think been awhile since i used it will try to check when i can

gary wise

you can also find out from mrc or the group