Sunday, February 6, 2011

Building a decoder tester

I have always found it useful to have a "simulated locomotive" with an actual motor to test decoders.  Back when I started working with DCC, I threw something together from the junk box and ended up using that for many years.

In 2010 that one finally fell apart and I set out to make a nicer one and here it is.

Here's a peek inside.   To keep things simple I mounted all of the components on the top half of the two part plastic project box.  The size of the box is 5-1/2" x 3" x 1-1/2".

The cord that comes out of the box has a Cinch Jones connector on it that I can plug into these two receptacles on my layout control panel.  The layout uses a Digitrax Chief System.

I also have an old Digitrax Big Boy system mounted on a board that I use on the work bench and this decoder tester can also be plugged into that.

Here's a drawing and a parts list along with where I found them.

Besides marking the color for the binding posts, the banana plug sockets are for any special leads needed to connect to board type decoders.

  1. The nickel plated binding posts are Grayhill 29-100 BLK which I purchase from Allied Electronics.  Their part number is 948-7392.  At $4.79 each, this was the most expensive part of the project.
  2. E-Z Hook 9284-5R is a set of banana plug jacks that I found at Fry's Electronics for about $6.00.  The Fry's part number is 18206.  The full set had 10 jacks with colors matching the wires on a decoder.  I did not use the violet or brown ones but if you are working with HO scale decoders that would be something to consider.
  3. Motor assembly from Kato E8 or PA locomotive.  I used this one because the mount was easy to attach to the inside of the box with Walthers Goo.  A striped pattern was printed on adhesive labels and attached to the flywheels to the motors rotation would be easy to view through the windows.
  4. Three yellow LED's taken from Atlas locomotives when they were upgraded to bright white LED's.  One each for the white, yellow, and green (F1).

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