What I think you're asking about is a light board. There are decoders (both sound and regular) that are made to "drop in" and take the place of the light board. Soundtraxx makes sound ones, so if you have say an Atlas GP you can get a lightboard replacement decoder and remove the Atlas lightboard and install the Soundtraxx one. Just need to attach a speaker (I use a 1/2" speaker with enclosure) and you're all set.
All decoders come with a circuit board. The wires are attached to it. Since the decoder isn't part of the normal stock engine you have to use the wires to connect it. Cutting the wires to the proper length is allowed and taping, gluing, etc. to keep the wires neat is also allowed.
I guess the neatness of an installation depends on your abilities and how picky the installer is.
I have hard wired DCC & sound decoders but I have been an electronic technician for many years so, for me it was easy. One install I made up my own pc board for tie points which made installing in a steam loco tender much easier. Your mileage may vary. You have to be specific about what scale, what brand/type of loco, steam or diesel. Many locos that are not DCC ready may need the motor isolated to start with.
Search Google for DCC information. There is a lot of info. Search this forum for DCC install to start with. Get some basic knowledge about DCC first. Store the results in your PC for future use.
Do a search for DCC sound decoders. There are many possibilities.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
alloboard wrote:and you installed a DCC decoder how do you wire a sound decoder into the locomotive.
Hmm. Not clear from your post. Do you mean you already put in a two function DCC decoder for motor and lights and you want to add a purely sound decoder to this setup? Or are you thinking of removing your DCC decoder and installing a typical (3 function) sound decoder (i.e. motor, light, sound)?
In any case, adding any decoder where there is no circuit board is called hardwiring, and there is nothing particularly hard about it, other than that you have to know what wire connects to which decoder lead and you will have to use some shrink tubing etc. Depending on the loco, you may have to isolate the motor and add some leads to the truck pickups from the tracks, and perhaps some wires to the motor contacts. There are plenty of examples already posted of this proceedure, but ask again if you are stuck.
Your desire to add a circuit board and then a decoder to it is a waste of time.
WOW why are you complicateing a simple instal? 99% of my decoders and all my sound decoders are hard wired. The decoder becomes the circuit board. If your worried about lights just add a resistor to the yellow and green wires.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!