Märklin Digital is totally compatible with 3-rail model railroads and AC or DC motors. It's true that the Märklin system is a 3-rail AC system, but the Digital control materials are independent of Märklin's method of HO model railroading and will work with most model railroad systems.

The main Digital controller (Control Unit #6021) is not exclusive to either AC or DC current, nor is it limited to 2-rail or 3-rail operation. The 6021 is powered by 16 volts of constant AC current, but that does not limit it to AC motors. The current on the track and the signal from the Control Unit is used by all of Märklin's Digital decoders.

It is the Digital decoder which is unique to AC or DC current. None of Märklin's decoders are limited to a specific track system, but the decoders must be chosen to match the motor type in the locomotive. It is possible, for instance, to operate AC and DC motors on a layout with just the Central Unit (6021) sending code to both type of locomotives.

With AC motors on 3-rail track you should use the following decoders:

6080 - for most HO locomotives with AC motors, range of 80 addresses/one auxiliary function.

6603 - DELTA decoder with 15 addresses/no function control.

6095 - 1 Gauge decoder which can be set to either AC or DC, 80 addresses/five functions.

With DC motors on 3-rail track you should use the following decoders:

6081 - for most HO locomotives with DC motors; full range of 80 addresses/one auxiliary function.

66913 - Smallest decoder originally made for HO with DC motors and limited space; 15 addresses/no function. Size = 14mm x 18mm.

65853 - Maxi decoder for DC ironless core "can" motors; 15 addresses/no function control. Also suitable for 3-rail O gauge locomotives.

6095 - 1 Gauge decoder which can be set to either AC or DC, 80 addresses/five functions. Also suitable for 3-rail O gauge locomotives, but requires more space.

61253 - DC decoder orignially used for the Märklin Köf HO model.

64001 - DC decoder orignially used for the Märklin Glaskasten HO model. This decoder has an extra output for lighting coaches through current conducting couplers.

211410 - HO decoder for the 3611 and 3614 which has a Faulhauber can motor. This decoder is a unique shape designed to fit into the loco's tender.

673470 - HO decoder for the 3711 which has a Faulhauber can motor. This decoder has a unique shape designed to fit into the locos tender.

Accessory Control

Accessories which require constant current such as motor powered items, and lights would use the k84 decoder. The k84 (6084) contains additional relays for switching current. Each k84 contains four double throw single pole digitally controlled switches.