At the 1992 Nüremberg Toy Fair Märklin introduced DELTA as its newest program. The DELTA system was a hit at the fair, and one toy newsletter in Germany said it was one of only three things worth seeing at that year's fair.

DELTA is simply a command control system that eliminates complicated wiring and yet achieves multi-train operation with just two wires to the track. But, you say, so is Märklin Digital. Why introduce another product to do the same thing? There is a segment of the model railroading hobby that Digital has a hard time satisfying. That is the beginner, or the modeler with a small layout with a couple of engines. After reading this review of the DELTA program I think you will also be enthused about the possibilities of this new program.

The system consists of three parts:

1. The controller
2. The locomotive module
3. DELTA Pilot

1. The DELTA Control No. 6604

This is a blue control box about the same size as the 10 watt transformers for conventional Märklin electric trains. The controller has a red selection knob on the top with six positions. The two outside selections are STOP positions and are used to shut down the entire system in case of an emergency. The right hand stop allows the controller to serve as a booster in the Digital program and the left hand stop will reset all running locos to speed zero when the transformer knob is reversed three times in succession.

The four middle selections are numbered pictures of the four types of locos that can be controlled with a multi-train system. Picture 1 is a steam loco, picture 2 is a diesel loco, picture 3 a railcar, and picture 4 is an electric loco. On the back of the DELTA Control unit there are three wires which connect to a conventional 16 volt AC transformer/controller and four sockets for attaching the DELTA Pilot unit and the feeder track wires. The brown and red sockets are labeled for the feeder wires and the other two sockets are numbered I and II for the Delta Pilot. The three wires to the transformer connect to the red and brown sockets where the feeder tracks normally connect and provide the ground and variable speed; the yellow wire connects to the yellow accessory socket to provide constant power to the DELTA Control.

The controller connects to a standard transformer for operating 16 volt AC trains. It does not connect to a digital transformer or the Märklin lighting transformer, you must have the variable speed control knob to operate the locos. This is one of the advantages for the current operator of a small layout. They can add the DELTA Control to their system and use the existing transformer for train control. The DELTA Control/Delta Pilot combination have a maximum of 5 locos which they can operate simultaneously, and so it is necessary to connect the DELTA Control to MärklinÍs 30 VA transformer.

When the DELTA Control knob points to one of the four loco pictures, the transformer speed control knob will control that specific loco. Once the speed and direction are set, the control knob can be rotated to select another loco, and the transformer will then operate that loco without interfering with the first one. As you rotate the knob past other loco pictures that may be in operation the system will not adversely affect those locos. The knob must be at a specific selection for about 1 or 2 seconds before the transformer can take control of a loco. This makes it possible to rotate the knob from picture 1 to picture 4 without making locos 2 and 3 accelerate or decelerate.

The speed control knob on the transformer is used to reverse the loco in the same manner as with conventional locos. A brief counter-clockwise twist to the left past 0 (zero) will reverse the loco with the same smooth action as locos equipped with digital decoders or electronic reverse units.

NOTE: The DELTA Control unit will not control conventional locos. The transformer needs to be connected directly to the feeder track to operate locos not equipped with the DELTA modules. The DELTA Control will, however, control Märklin Digital locos whose addresses are set to correspond to the four on the control unit as shown in the next section.

Conventional AC transformers - control all Märklin AC trains
DELTA Control unit - controls DELTA and Digital equipped locos
Digital AC Control units - control DELTA and Digital equipped locos

2. DELTA Module No. 6603

The module is factory installed in the DELTA locomotives with pre-set addresses that correspond to the appropriate pictures on the DELTA Control unit. These locos and the starter sets are all listed below and are available through any authorized Märklin dealer. The module is also available separately for retrofitting into conventional locos. The separate module, however, is available only through the authorized digital dealers, and the warranty on the module is valid only when installed by one of MärklinÍs digital dealers.

The DELTA module looks very much like MärklinÍs digital c82 decoder. It is quite small and has no address dip switches or function wires like the digital AC decoders. DELTA addresses are set with solder bridges at four locations on the module. This allows for more than the four basic addresses controlled by the 6604 controller. It also allows for address changes so a person could operate four of the same type of loco (such as steam) on the DELTA system. Each of the modules in the four steam locos would need to be different, so they could respond to the four selections on the DELTA Control unit. A person operating this type of layout would probably also want some way to identify the four different steam locos on the controller so they would know which loco is being controlled. A simple self-adhesive label with the class of the loco would suffice.

In order to keep the cost reasonable on the modules, there was no function added to them. Lights are either wired directly to the power inputs or they connect to DELTA module which reverses the lights with the direction of travel. Some locos and railcars even offer red marker lights, but there is no smoke or TELEX offered in any of the DELTA locos at the present time. The original locos equipped with the DELTA modules were:

3331 Class 140 red electric with reversing lights and close couplers in NEM pockets (address 24)
3374 Class 216 cream and blue diesel with close couplers (address 72)
3396 Class 86 tank loco with reversing lights and RELEX couplers, but no TELEX (address 78)
3428 Class 515 red railcar with reversing lights and red marker lights and close couplers (address 60)
- Class 89 tank loco in starter set 2916 (address 78)
- Class 81 tank loco in starter set 2964 (address 78)
3. DELTA Pilot No. 6605

The DELTA Pilot allows for a second person to control a single train with a walk-around (wired) hand held control unit. The Pilot attaches to a DELTA Control unit with two wires about 1 meter long. It will only control a single loco with the address set at 80. This can be a DELTA loco set by connecting all solder bridges or setting all DIP switches to "on". On digital locos set the dip switches with 1-3-5-7 on.

DELTA Starter Sets

In 1992 Märklin introduced two new starter sets which included locos equipped with the DELTA module. Starter sets do not include the DELTA Control unit, since there is only one loco in the set. Its not necessary to use a multi-train control unit until you have more than one loco. Customers purchasing the starter sets get the more powerful 30VA transformer and a loco with smooth action reversing similar to the 3300 series with electronic reverse units. When they graduate up to multi-train operation, they can then purchase the additional locos which are available with DELTA modules, or have modules retrofitted into any existing conventional loco, and they would also need to acquire the DELTA Control unit. Some initial purchases may be made for the entire package to get mult-train control immediately. But the important thing to remember, is that this larger purchase is at the discretion of the buyer, they are not forced into it with large starter sets. People can still start small and increase the size of the layout and number of locos at their own speed. The two starter sets were:

2916 Freight Train Set with M Track Oval - This set included a class 89 tank loco with DELTA module installed, 4 freight cars, bridge and pillars.

2964 Freight Train Set with M Track Layout - This set included a class 81 tank loco with DELTA module installed, 4 larger freight cars such as the crane car and lumber car, extra track and 2 turnouts.

Märklin has continued to issue DELTA Starter Sets each year. The most beautiful being the two anniversary sets in 1995 commemorating 60 years of HO model trains and 150 years of railroading in Württemburg.