LDT accessory decoders SA-DEC-4-DC & S-DEC-4-DC

SA-DEC-4-DC & S-DEC-4-DC from LDT (Littfinski): 2 sturdy accessory decoders used under the biggest model train layout in the world!

LDT (Littfinski DatenTechnik)

LDT is a (medium-sized?) manufacturer based in Germany, though their website is available in a few languages. They have a large range of DCC (and Motorola) products for digital model trains.

I suspect not so many people have heard of LDT (I hadn’t until I started shopping for trains in Germany). Why do I have those modules, and why are they worth mentioning here? Two reasons:

• The decoders are available (at least) EU wide. They are indeed sold by the German chain store Conrad Electronics, that I often mention here. This means the decoders are available through the national Conrad websites (conrad.de, conrad.nl, conrad-electronic.co.uk…) and through the global Conrad.com.
• LDT products are used under many large layouts. Including the largest & awesomest model train layout in the world: the Minatur Wunderland in Hamburg. LDT describes in details which models are used in Hamburg on this page. That sure speaks well for the reliability of the LDT modules.

Specs & pictures

The SA-DEC-4-DC & S-DEC-4-DC are two completely separate devices. They look alike, and it made sense to review them together since they share a very common purpose under our layouts:

• SA-DEC-4-DC – DCC 4x Relay decoder (German: Schaltdecoder)
  4 independently operated bi-stable relays  (for any item that needs constant power, e.g. lighting).

• S-DEC-4-DC – DCC 4x Switch decoder (German: Magnetartikeldecoder)
  For 4 double-coil switches (for standard N-Scale switches with coils and 3 wires).

Ready to use or DIY kits

Before having a look at the SA-DEC-4-DC & S-DEC-4-DC decoders, a few words about the LDT philosophy.

Most modules are available in 3 versions:

• DIY Kit – read to be soldered with the board and all needed components
• Ready to use board
• Ready to use board with plastic housing.

Obviously, the DIY kits are cheaper. Since the components are normal-sized, anyone with a bit of soldering experience should be able to build the modules successfully (20-30 minutes).

Conrad seems to only sell the first 2 versions, but you can buy the separate plastic housing if you want to:

• SA-DEC-4-DC – DCC 4x Relay decoder
  DIY Kit:  Conrad no. 212172
  Finished board: Conrad no. 212180
• S-DEC-4-DC – DCC 4x Switch decoder
  DIY Kit: Conrad no. 212113
  Finished board: Conrad no. 212121
• Plastic case LDT-01 for both models: Conrad no. 240015

Programming

Those modules are, by design, extremely simple. There are no CVs, no complicated settings. For both decoders, programming is done the old fashioned way, in a few seconds.
Just press the programming button, send an order from your command station, the module then takes the corresponding address and the 3 following (e.g. send 1, modules gets addresses 1 to 4).

Tests and impressions

The switch decoder works well with classic points (in my case, Fleischmann N).
Unfortunately, the relays on the relay decoder are a bit noisy. This is not unusual, since relays are actual mechanical devices. I use these to switch some layout lights on and off.

I have had those modules under different versions of my layout for more than 4 years. Some I had bought as DIY kits, others as ready to use modules. Those modules have always worked completely reliably, although my layout isn’t as intensively used as the Hamburg Wunderland !

Conclusion

The LDT switch and relay modules are single-purpose no fuss devices. They do little, but they do it very well. Programming couldn’t be easier, and if you can solder, the DIY kits will save you a bit of money (e.g. as of July 2014, the switch decoder for 4 switches costs about €21). Beginners can get the ready to use devices.

My personal choices have evolved. Because my layout is always evolving, I now prefer to buy universal modules. Those can be reprogrammed for any purpose (switches, lights, signals). The drawback is they are more complicated, and sometimes more expensive. I recently reviewed the advanced Qdecoder Z2-8+ which is now one of my favorites.
Despite this change of heart, LDT modules still operate many essential parts of my layout. I would still recommend them to people looking for simple & reliable DCC devices.

External links

• The official LDT page for the switch decoder (“Turnout decoder”): http://www.ldt-infocenter.com/dokuwiki/doku.php?id=en:s-dec-4
• For the relay decoder: http://www.ldt-infocenter.com/dokuwiki/doku.php?id=en:sa-dec-4
  The relay decoder is erroneously called “switch decoder” in English by LDT. Do not confuse it with the actual switch decoder, called “Turnout decoder” by LDT.

I always try to be fair and square when giving grades, see the details about the evaluation criteria here !

Reminder: I am a hobbyist and these articles only represent my personal views. I am not receiving any compensation, in any form, from the brands or stores mentioned here. The product names, marketing names, and brands mentioned here are the property of their respective owners.