Minding my P’s and Q’s… wiring for the DCC programming track

The 4pdt switch for the DCC programming track with all its wires soldered in place and an LED holder to display the status
The 4pdt switch for the DCC programming track with all its wires soldered in place and an LED holder to display the status

I get most of my LED’s from Handsignalman LED’s on eBay and he also does these LED holders for 3mm LED’s. I’m using an LED to indicate when the track is in ‘programming mode’.

4pdt switch and programming track wiring
4pdt switch and programming track wiring

I’ve done this wiring diagram, as much for my own sake as anyone elses, to try and make the operation clearer. So, when the switch is in one position it supplies normal DCC power feed to all the sections of track, but when in the other position it kills power (‘J’&’K’ Lenz terminals) to both end sections, provides programming feeds (‘P’&’Q’ Lenz terminals) to the middle section and lights the LED.

All the connections are insulated with heat shrink tube, and all fitted with wire end ferrules, except those for the LED
All the connections are insulated with heat shrink tube, and all fitted with wire end ferrules, except those for the LED

The whole wiring of the switch was greatly helped by my acquisition of a temperature controlled soldering station with money I got for my birthday.

One of my recent acquisitions (birthday present) a temperature controlled soldering station

Once the wired switch was installed into the back of the housing it reminded me of the back of an old television tube. Anyway, all I’ve got to do now is connect it all up.

Switch installed into the rear of the housing ready for connecting
Switch installed into the rear of the housing ready for connecting

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6 thoughts on “Minding my P’s and Q’s… wiring for the DCC programming track

  1. Hi I take it there is a gap in the rails on the adjacent pieces of track to the Isolated sections which you havent shown on the diagram and if so is that to stop a train inadvertently running into the programming section from either end?

    • Yes there is a gap in the rails, and yes, the isolated sections are to stop trains running from the live sections either side straight onto the programming track, and frying the decoder ‘with one foot in both camps’.

      • I wondered what would happen if the gap got bridged by a loco, didn’t realise it could fry the decoder! Thanks for the advice. I’m setting up something similar but it will probably be a siding and only need isolation at entry. I going to wire a switch the same so I have the option.

  2. Glad you found the information useful Peter. I hope you find your own project as rewarding and as much fun as I have.

    Cheers,
    Ian

  3. Hi Ian

    Ive set up a switch the same as yours. It all works as expected except that when I enter the PROG menu the power to the rest of the layout is disabled and the led goes out. On exiting PROG menu normal service is resumed and the switch LED comes back on. Having not used a Lenz before I wondered if you have the same symptom. I assumed that the rest of the layout would just carry on operating when in PROG mode hence the reason for the Programming track?

    Cheers

    Peter

    • Hi Peter,

      I’ve finally rewired my 4PDT switch, after a slight glitch, and had chance to test my system. The answer is yes, my layout behaves exaxtly as you describe. When I set this up I was under the impression, like you, that the rest of the layout would probably behave as normal. Seems I was wrong. However, The main reason for doing this was to have a piece of track on the layout that could be used as part of the running track or as a programming track. This saves having part of the layout which can only be used as a progamming track. In this sense the switch does what it was intended to do. It allows you to drive engines onto a programming track.

      I hope that clears things up!

      Cheers,

      Ian

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