Monday, November 18, 2019

Building a DCC sound car

It's been ages since I posted anything new on this blog.  I have been busy building my layout over the last couple of years and already have decoders in nearly all of my locomotives.    Here is something new that I finished recently.

I actually started this project a few years ago.  I got it working but was not satisfied with the way the sound cut out whenever good electric contact between the wheels and the rails was lost.   After purchasing some TCS KA1 keep alive modules and some better quality metal wheel sets I wanted to try to finish it up.

The car I am using for this project is an Atlas 4 bay ACF covered hopper.   The decoder is an older version of Soundtraxx.  I built this speaker sound box from scraps of styrene to be placed over one of the high points between the bays of the hopper.  This really helps amplify the sound.

I cut out the between bay areas on the bottom of the car, one for the speaker box and two to make room for the decoder.  The axle contacts were made from .010 brass strip with brass screws used to hold the trucks in place.

Here is some detail on how I did the wheel pickups.  The Atlas metal wheels were later replaced with BLMA metal wheels which worked much better.

This does not roll as freely as it would without the axle wipers but this car will be right behind the power so should be OK.

After carefully cutting and removing the heat shrink, and then removing the metal heat sink shown here on the right, I found the places to connect the Keep Alive circuit wires.

That a heat sink that needs to be put back after the wires are connected.

Here is a close up photo of the TCS KA1 Keep Alive module connections to the decoder.  After soldering the wires from the KA1 to the Soundtraxx decoder, the white plastic heat shrink was re-install and secured with scotch tape.
After getting the decoder and speaker inside the car the KA1 will fit over the decoder if the 6 capacitors are bent out flat as shown in this photo.
And here is the car with everything inside.  It's a tight fit but the lid will fit.

A demonstration of the sound is on this Youtube video.


  1. Excellent work sir! Was this started before sound in n scale got so popular? Just a tip but I've found that sealing the speaker enclosure really helps amplify the sound.

    1. Thanks. By sealing do you mean the opening on the bottom ?

  2. Don't know if you will get sent a notice if a comment is made. Could find no email or other way to get in touch.

    I'm wondering if you are still operating the blog and if not why not. Just concerned as this last year as taken a toll on everyone.

    I've taken the liberty of copying all your posts as they seem like they could be valuable. Especially to someone like me just starting out in DCC and N Scale.

    Hope all is well and that you were taking a long vacation. You can reach me at (remove the at and use the symbol) jwallin at

    1. Hi and sorry for the late replay. I am fine, thank you for your concern. I don't get any notification of a new comment until I check the blog myself. The reason there have not been any new posts is that I have retired from doing installs for others and so do not have much new material to post on. I am still active in the hobby building and operating a layout and trying to finish getting decoders into my last few locos that don't have them. My E-mail address is