how many functions do i need in a decoder

[tommy2tap]

i have an atlas rs3, the old white and yellow box(#7070) and an older spectrum gp30. i just just made the jump to dcc. i want to start with motor controller decoders and possibly add sound later. would the addition of a sound decoder require 3 seperate funtions on the motor decoder to access engine,bell,andhorn sounds or just 1 to get all three from the sound decoder. i'm new to dcc and want to enjoy it as much as possible but still not quite sure about the details. i have a first generation prodigy system i picked up for almost nothing just to get started, plan on going digitrax in the next 18 months or so HOPEFULLY. any advice guys? besides ditching the prodigy now.. 

[jrbernier]

Tom,

  Basic decoders have an F0F & F0R function for the front and rear headlight.  Sound decoders will have the bell/whistle/prime mover built in.  Most sound decoders use F0 to turn on the headlights, F1 to ring the bell, and F2 to blow the whistle.  Beyond that, it depends on the brand/model of decoder.  Note that there are 'function outputs' and 'funcion keys'.  Function keys can be re-mapped to do turn on/off various function outputs.  Each decoder will have a manual explaining the output functions and what function keys control them.  Most newer decoders support function re-mapping.

  Your Prodigy will work with these decoders - Sound is not a function of the command station.

Jim

[MisterBeasley]

The "functions" on a decoder refer to the number of outputs the decoder has.  Sound is not considered an ""output" for this count.

As Jim said, the standard 2-function decoder has 2 outputs, generally used for the front and rear headlights.  4-function and 6-function decoders have extra outputs for ditch lights, Mars lights and rotary beacons.  The extra functions are almost always used for lights, although I think someone makes electrically-operated couplers that might use them.

[rrinker]

 The sound functions in a sound decoder are independent of any extra control outputs used for lights. Most sound decoders have at least 4 light functions in addition to all the sounds, F0F and F0R for the front and read headlights, plus two others for ditch lights or other uses. There will be that plus the 12 or more sound functions.

                --Randy

 

[simon1966]

Hi, is it Tom?

About decoders.  If you start with a non-sound decoder then the number of functions that you need will be determined by the lighting needs of the loco.   Most decoders will have the minimum of 2 for the front and read headlight.  For the generation of locomotive you are using, that may be sufficient.   Additional functions could be used to independently light number boards, or the cab.  On more modern diesels. you might want ditch lights or rotary beacons, things like that.   However for the most part a 2 function decoder will give you the motor control and the two headlights.

When it comes time for sound you have 2 choices of approach.  The first is to replace the motor decoder altogether with a Sound/Motor decoder.  The sounds don't count as functions, so the number of functions will again be determined by the lighting effects you want.  Most sound decoders will have 4 functions as standard, so most likely more than enough for your needs.

The second approach is to keep the motor decoder installed and add a sound only decoder, such as a Digitrax sound bug.  This introduces some complexity, splicing wires together and then correctly setting up and running 2 decoders to work nice together.

Personally I would opt to replace the motor decoder, you can then use that decoder somewhere else.

 

In either case, adding sound to these locos is going to be a bit of a challenge.  Both locomotives are going to require that you hard wire the decoders.  The RS3 is going to be fairly tight quarters for a decoder, let alone a speaker and sound decoder.   if the Spectrum is one of the split frame era models, it can be converted to DCC, but there will be very little room inside without some frame modification for the speaker.

I just converted a pair of Yellow box Atlas locos, one made by Kato, the other a Roco, and they both proved to be great candidates for DCC.  Hard wire jobs for sure, but very smooth running locos.