The Digitrax DS44 is new in late 2001. It is a smaller brother of the DS54. Two reasons why I decided to get this decoder instead of the DS54. First, it is cheaper. Second, it is available! I had the DS54 on backorder for almost 6 months and I got tired of waiting. The DS44 is cheaper because it is less capable than the DS54. Also, the DS44 is only meant to be used for stall motor switch machines, such as the Circuitron Tortoise. This is what I use.

The DS44 is quite simple to install and operate. The two wires on the right of the photo are the ones providing the power and control to the unit. I attached them to the bus feed wires running under the layout. I attach the decoder with some velcro to the L-girder benchwork. The wires on the left of the photo are the ones that get connected to the Tortoise switch machines to control the position of the turnouts.

The diagram below shows how one of the four outputs of the decoder is connected to one Tortoise. I use a 1.68k Ohm resistor (actually a 1k Ohm and a 680 Ohm resistor in series) to perform a voltage drop. This voltage drop makes the Tortoise move slower, which is what I like. Besides that being more prototypical, it is also far less noisy in the room. For a crossover (where two turnouts are moved simultaneously) I put the Tortoises in parallel with each other and the resistor is changed to just a 680 Ohm value.

References

• Tony's Train Exchange excellent evaluation of the decoder.
• Digitrax DS44 decoder instructions.