Decoder Buddy Mini

The Decoder Buddy Mini was developed to fit into smaller steam and diesel applications.  There has also been interest in HOn3 and S-Gauge applications.

This mother board does not include the 21 Pin Decoder.

This mother board requires soldering.

This printed circuit board is NOT INTENDED FOR USE IN A DC SYSTEM.  However, if the decoder you are using supports DC operation it should work.

The Mini comes with three different sets of standard resistors 2.2K, 1K and “0” Ohm.  The dealers and distributors stock 1K versions unless otherwise stated.

I can substitute / supply 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 output pads
  • One set of stay alive pads (U+, GND and if necessary, a third control wire) If using an ESU ‘Power Pack’ we recommend A10 as mentioned below.
  • Two logic outputs to control a Power Pack, smoke unit(s) or servo. The two logic output pads are 5 volt outputs with no resistors and controlled by A10 and A6 as labeled.
  • One pair of speaker pads
  • The correct headlight orientation is shown on the Mini.

 

Resistors for use with LED lighting. The “0” ohm resistors accommodate previously installed LEDs with resistors in line and “12-volt LEDs”.  It is IMPORTANT to realize that resistors must be used when LEDs are connected to the four lighting outputs of the “0” Ohm or the Tiny!!!  Resistors may be soldered in line when purchased or the included resistors may be soldered inline upon installation.

Resistors for use with incandescent bulb lighting. Remember there are different incandescent lamp voltage requirements and current draw that must be taken into consideration also.  A single or two separate bulbs may work but multiple bulbs can be problematic.  The “0” ohm resistors should provide the voltage and current necessary for incandescent bulbs.  A ½ watt resistor at the very least should be used to reduce the voltage to the bulb and heat is a major consideration in this installation.  I strongly recommend LEDs.

Resistors included on the Mini are standard and 1K.  Values of the smd resistors appear in a white circle on the package for both standard smd resistor values.

 

Decoder Buddy Mini Size

Width x Length x Height
0.65”  x  1.35”   x   0.35”
17 mm x 35 mm x 9 mm

Height may vary slightly depending on decoder.

Minimum measured height is 0.35” by trimming the 21-pin connector pins flush with the top of the decoder‘s 21-pin connector.

Light Test Board

With the abundance of lighting functions and wanting to see and check them before I placed the shell on the frame, I decided I needed a way to see what was happening!  I went to work and prototyped a small connector board with LEDs so I could put the frame on the test track and test the motor, speaker and lighting functions before assembling the locomotive.  The Light Test Board is also a good diagnostic tool to see if the decoder and motherboard are behaving properly!

The Light Test Board works with the 8 output Original Decoder Buddy, and both the 12 output V5 and V5B.

Decoder Buddy solder pads for different manufacturer's 21 pin decoders

I’ve been getting a number of questions about the nomenclature on the pads of the small connector board. It is a little confusing at first. Here is a table that should straighten out the pad labels.

The first column has the pinouts from the 21-pin connector. The second column has the pad labels on the original Decoder Buddy’s small connector board. The third column has the pad labels on the V5 Decoder Buddy’s small connector board. The rest of the columns are the output labels of the different manufacturers 21-pin decoders. This chart should clear up any questions or confusion. If not, feel free to contact me