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Decoder Buddy Main Board and Connector Board Version 5

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Your Price:
$12.99 (You save $3.01)
0.10 LBS
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Product Description

This new board makes for super-easy 21 pin decoder installs from vendors such as Digitrax, ESU, SoundTraxx, and TCS!


Now a 21-pin-friendly board replaces the standard DCC 8-pin loco motherboard and easily allows taking full advantage of all the functions and features of the latest new feature-rich decoders. The benefits of this new Decoder Buddy (DB) board include:

1. Popular 21-pin decoders from TCS, SoundTraxx, ESU and Digitrax easily fit in Decoder Buddy‘s 21-pin socket

2. 10-pin socket and plug with wire-outs for 21-pin decoder functions

3. 10-pin plug fully removable for easy separation of loco shell and chassis

4. On board resistors for LED lighting provided


5. Specifiable resistors for function outputs available on request


6. On board soldering pads for stay alive


7. Older 8-pin loco motherboard weaknesses solved with Decoder Buddy


Fits Most HO Scale Locomotives

It has a small footprint of

2.20" x 0.67" x 0.35"


56 mm x 17 mm x 0.9 mm

which makes for easier DCC decoder installation in the some of the tightest locomotives!


Connections for 8 Lighting Functions

 Depending on your DCC decoder manufacturer up to 8 lighting functions are available with amply sized soldering pads for your LED leads for easy decoder installation


 Specifiable resistors for function outputs available on request make retrofits of retrofits or bulb use even easier


Connections for a Stay Alive of Your Choice

Two pads are available for connecting a stay alive to keep your model trains running smoothly



















Decoder Buddy Information

This product is versatile in terms of direction of the placement of the board and mounting in various configurations. It can easily replace a QSI board, a Dual Mode decoder board or be mounted directly on the electric motor or frame with Kapton tape. (It is recommended that a piece of Kapton tape be placed on the bottom of the mother board to assure electrical isolation from the electric motor or frame.)


This mother board does not include the 21 Pin Decoder.


This mother board and connector board require soldering.


These printed circuit boards are NOT FOR USE IN A DC SYSTEM.


The on board resistors are sized for LEDs. (2.2K)

Now I have added Decoder Buddys with 0 ohm, 750 ohm and custom specified resistors for function outputs. These may be requested by the email link.


The mother board includes;

One 21 Pin Decoder receptacle,

Two pairs of track input pads,

One pair of motor input pads,

One pair of stay alive pads (U+ and GND),

Two pairs of speaker pads wired in parallel,

Resistors for use with LED lighting. (on board 2.2K) (Also available with 0 ohm, 750 ohm and custom specified resistors for function outputs. this accommodates incandescent lamps or bulbs.)


The connector board contains pads for eight pairs of lighting function connections. U+ or the blue wire has eight connected pads for the common power source. The negative (-) discrete function pads are all labeled to indicate their connection to the functions available in the decoder.

If you require incandescent lamps there are procedures that require soldering and allow for incandescent lamp use or different Decoder Buddys made specifically the application. Remember there are different incandescent lamp voltages and current draw that have to be taken into consideration also.

The lighting connector was designed so that the shell of the diesel locomotive can be easily separated from the frame without unsoldering wires. This does require that the headlight and rear lights be mounted in the shell of the locomotive and that the diesel has a removable dynamic brake shell.

Decoder Buddy installed, speakers installed, decoder installed, and the motor is tested and ready.
Decoder Buddy installed, speakers installed, decoder installed, and the motor is tested and ready.

Width x Length x Height


O.67” x 2.20” x 0.35”


17 mm x 56 mm x 9 mm


Height may vary slightly

depending on decoder.



                  Original            V5 

Pin #       Decoder       Decoder     LokSound     LokSound     SoundTraxx    TCS     Digitrax**           

                   Buddy           Buddy              V4                      V5                  T2 & E2


  1                                         A10                                              A10

  2                                         A7                                                A7

  3                A6                   A6                     A6                     A6                                               F6*           F6

  4               A4                   A4                     A4                     A4                        Fx6              F4             F4

  5                                         A12                                              A12

  6                                        A11                                               A11

  7               F0r                 F0r                    F0r                   F0r                       F0r               F0r          F0r

  8               F0f                 F0f                   F0f                    F0f                       F0f               F0f         F0F

 13               A3                    A3                      A3                     A3                        Fx5                F3            F3

 14              A2                    A2                      A2                    A2                        Fx4               F2            F2

 15               A1                     A1                      A1                     A1                         Fx3                F1             F1

 17              A5                    A5                      A5                     A5                                                F5*           F5


* Note: TCS functions 5 and 6 are not programmable, and will only output constant bright lights.

** Unavailable for comment


An added benefit of Decoder Buddy beyond easy DCC decoder installation is YOU CHOOSE lighting functions. Upgrade the motherboard that came with your locomotive for all the lighting functions available in your 21 pin decoder! Ditch lights, blinking ditch lights, numberboard lights, step lights, ground lights, class lights, the list goes on.



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