This is a quick overview of the fixed DCC decoder by TrainModules, a Hungarian manufacturer that has been distributed by Conrad in Germany for more than a year.
This decoder is what I call a hybrid decoder. It can send either impulses (e.g. for electromagnetic switch motors) or permanent power (e.g. for signals or motorized switches).

(part of a series where I will review similar decoders from other brands)

Train Modules DCC Accessory decoder

Form factor

The main feature of “TrainModules” modules is that they are very small (using SMD components) and fit well under “electronically crouded” layouts. This module is no exception, with a size of  62 x 58 mm (2.4″ x 2.3″).
Also a common point for TM modules: the board is not protected by a casing, and none is available (to my knowledge).

Connectivity

The decoder can control 4 devices with 2 outputs, or 8 individual outputs (standard on this type of decoder).
It has a 2 separates power inputs, one for the DCC signal, and another for actually providing power to the devices. This is a standard features on many accessory decoders now, it allows draining as little “precious” DCC power as possible, by actually powering the attached devices with a separate circuit (e.g. a cheap 16V power supply).

Features and programmation

The module address can be programmed either by CV editor or by the usual “press program button then send order on the desired address” method.

The module allows more precise programming via CVs. Above all, this allows using each independent output as either a permanent or an impulse output. Impulse outputs can even be modified for a certain amount of time in milliseconds.

The absence of Railcom, however, means CV editing has to be done on the programming track (no easy reprogramming the module – except the addresses – once it has been installed).

Reliability

I wouldn’t call the module unreliable – I am not a professional tester, but I noticed two annoying issues after using those modules for months:

  • The DCC polarity seems to matter for programming (no idea why)
  • Some orders aren’t executed if your are sending order too close one to another. In my case, I had to set my PC to only send orders with 500ms delays between each to achieve reasonable reliability. This may be due to the fact, however, that I have connected “heavy” load switch motors to the decoders. They may be more reliable with low-power (or short) devices attached.

Until I can find why I have had issues, I will be using those decoders only for non-critical accessories (i.e. everything but switches).

Conclusion

All in all, this is a good versatile decoder to place under a layout. The fact that it can be used for impulse and permanent outputs is a plus: it is practical to be able to use the same decoder for – say – 2 switches and 2 red/green signals at the same time.

I am not sure why I am noticing some reliability issues, and would welcome feedback from other users.

Update 2014-02-08 on reliability:
It seems this decoder has problems with switching high load devices (e.g. coil turnouts) in fast sequence. When switching all 4 turnouts through my PC software (Train Controller Gold), through my ECOS II, I noticed the 3rd and 4th turnouts fail to change position in about 50% of the case. It seems the decoder tries to switch all turnouts simultaneously and cannot handle the load. 

Based on this experienced, I would not personaly recommend this decoder, especially to people using automation (whereby high speed sequences of changing a lot of turnout positions are usual).

CriteriaNoteComment
Price per connected device
(1 std device=2 outputs)
7.50 €Based on unit price in Germany (2012/11)
Connectivity5 / 5Incl. separate power circuit
Fonction as impulse decoder
& perm.decoder
5 / 5Programmable for each output.
Programming2.5 / 5Button for address + CVs for additional options. No Railcom.
Reliability2 / 52 issues noticed on my layout.
Form factor4 / 5Very compact, no protection of the board.
TOTAL3.7 / 5

External links

Usual review disclaimer:
Reviews are personal opinions based on my own experience. They are limited to the specific use I choose to make of the reviewed devices, and the specific hardware version I have at hand. I am not a technician, nor a model railroad expert; these reviews aren’t intend as a quality judgment on the device.