Märklin decoders

The Märklin locomotive decoders are a set of the components of the Märklin Digital system for controlling model trains.

The decoders are inserted into the locomotives and were made to be small enough to replace the original reversing mechanism found in Märklin locomotives.

First Generation

The initial decoders were based on a Motorola chip and were sold under the catalog number as follows: c80 6080 (for AC) c81 6081 (for DC) c90 6090 (for 1 Gauge - i.e. with higher current outputs)

These provided the following outputs: - Forward and reverse - Light function (on only when moving forwards) - Light function (on only when moving backwards)

In addition, the decoders would also work in the traditional analog environment where in the AC rail current varied in voltage and a 20V current spike would toggle the direction of travel. The light output function only worked in digital mode.

The decoder produces 14 speed steps in each direction. The speed of the locomotive is regulated by pulse width modulation. That is the track current is switched on and off rapidly and the time for which the current is switched on is proportional to the speed step. Thus speed step 3 has the power switched off for longer than it is switched on and conversely step 13 has it switched on for longer than it is switched off. This results in different locomotive speeds and allows the speed of each locomotive to be controlled.

Later a newer version of the Motorola protocol was used and so the first series are known as Old Motorola and the new series are known as New Motorola.

The newer version actually introduced an additional 13 speed steps between the original 14 thus providing 27 effect speed steps. Since the controllers and computer interface could not be changed to express the 27 steps, the new speed steps were achieved by switching between the original 14 in different sequences. For example going from speed step 4 to 5 actually produced a speed between 4 and 5 - termed 4+. If one went from speed step 6 to 5 one would instead get the original speed step 5.

Delta

The new Motorola decoders were also used in the range of cheaper digital systems called Delta. The decoder was designated c95 and sold under catalog number 6095. These decoders also varied over time. The Delta system was designed to work with just 4 different addresses. As a result, the Delta decoders could only be set to one of the four addresses. These decoders could also be used in the 'normal' digital environment.

The decoder has a DIP Switch that is used to set the address of the decoder. Commands sent out via the rails reach all the locomotives on the track and each decoder only responds to commands that match its own address. The address of the decoder could be set to any number between 1 and 80 allowing up to 80 locomotives to be controlled independently.

c91

The c91 decoder was a better performing decoder that added the ability to control the acceleration and maximum speed by adjusting two small pots on the decoder. The catalog number is 60901

In 2004 Märklin introduced their second generation of decoders - the mFx decoder. The decoders themselves are produced by ESU.

The mFx decoder supports up to 128 speed steps and they also support multiple function outputs so that lights, smoke units etc can be controlled. Some also include support for producing sound via a small speaker that is also mounted inside the locomotive.

Modern decoders can have numerous settings programmed to configure factors such as the acceleration, speed curves, lighting effects etc.