How to make a reliable test track in your Märklin workshop

Updated 2012-08-18

The roller stands from different suppliers are very nice, but I like to make things myself, and spend the money I save on locomotives and so on.
For my work desk I have made a simple powered workshop C-track.

The twisted pair of wires is the power supply from my layout.
I have glued in two connectors and installed an LED, to indicate that the track is powered.  The LED is connected via a bridge rectifier and a 1500 ohm resistor.
For power supply outside the track, I have made some long wires, with a Märklin plug in one and and small insulated crocodile jaw in the other. I have four of these; a red and a brown (in the photo), and a yellow and a black one.

Running a locomotive outside the track is also possible, for example a four axel steamer.  In this case, the locomotive is connected to ground with the brown wire and gets the power from the front roller.

To do this, I have made five rollers. Five normal "2x2 knob" Lego bricks, cut off the knobs and install four roller bearings. The bearing outer diameter is 9 mm, the inner is 4 mm. Using 3 mm screws, some adjustment is possible.  Small washers are installed behind the bearings on one side of the brick, to achieve the correct track width.
I had to make some grooves in the Lego bricks, between the bearing, to give space for the wheel flanges.  For the same reason I had to cut off a part of the inner washers as well.

Two of the rollers have an electric connection for the pick-up shoe.  The ground connection is always made with the brown wire in the above photo, directly to the locomotive.

To run a locomotive with bogies is no problem either:

In this case the locomotive picks up it's power supply from the C-track. Electric connection to the rollers are not required.  A locomotive with two powered bogies requires of course four rollers and separate power supply.

As mentioned, the test track is connected to my test layout, a double oval. The outer oval may be switched from normal track to programming track.
The workshop track is connected to the outer oval, which means that also the workshop track may be either a normal track or a programming track.
The workshop track is connected via a Märklin k83 decoder and signal relay (a k84 decoder also works perfect), so I can cut the power when e.g. soldering on a locomotive.

Normal running of the two loops: upper left icon
Programming track operation: lower right icon
Workshop track on/off: icon no. 2 from the lower right corner.