Turnout Slow Motion Switch Machine Breakout Board Assembly Guide

Table of contents
  1. Turnout Slow Motion Switch Machine Breakout Board Assembly Guide
    1. Introduction
    2. Assembly and Component Placement
    3. Tools Required
    4. Safety Precautions
    5. Testing and Verification
      1. Visual Inspection
      2. Functional Testing
    6. Troubleshooting
    7. Appendences
      1. Specifications
      2. How It Works
      3. Connections
      4. Protection
      5. References

Introduction

The Turnout Slow Motion Switch Machine Breakout Board, used in conjunction with the LCC LCC Fusion Node Card, Turnout Card, and a slow-motion motor based switch machine, provides both motor control and turnout point position sensing, while also handling frog polarity switching. The board leverages dual mechanical relays to reliably switch the frog between Rail A and Rail B, based on the turnout’s position. Each relay is responsible for controlling one frog, ensuring proper electrical connection as the turnout moves between the Thrown and Closed positions.

By interfacing directly with the Turnout Card, this breakout board provides a seamless way to control the turnout motor direction and manage frog polarity automatically, making it ideal for complex layout control and automation.

flowchart LR; 
can["CAN Network"];
subgraph layout ["Train Layout"];
n["Node Card"]; 
c["Turnout Card"];
direction LR;
can <--> |"LCC Event <br/> (on/off/speed"| n;
n <--> |"GPIO Signal <br/> (high/low)"| c;
c <--> |"Motor Control <br/> (Bi-Directional, 9V/12 V)"| bb[Turnout <br/> Slow Motion Switch Machine<br/> Breakout Board];
bb --> |"Motor Control <br/>(Bi-Directional, 9V12 V)"| m("Slow Motion Switch Machine <br/> (2x)");
bb --> |"Frog Power<br/> (Rail A/B)"| frog["Frog (2x)"];
tbus["TRACK BUS"] --> bb;
abus["ACC POWER <br/> (GND)"] --> bb;
end;
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class bb lSalmonStyle;
classDef lightGrayStyle fill:#d3d3d3,stroke:#333,stroke-width:2px,font-size:24px;
class layout lightGrayStyle;

Usage:

This breakout board is for use with 2-wire slow motion switch machines. Wiring examples:

Manufacturer Product Breakout Board to Switch Machine Connects Motor Resistor Bypass Turnout Card Motor Voltage Selection Frog Polarity Points Status1 Comments
Micro-Mark® Switch Tender Switch Machine 83201 Connect 1 to one connection
Connect 2 to other connection		 No 12 V Breakout Board Breakout Board 83201 Wiring (PDF)
Increase R1 to slow switch machine
Rapido Trains Inc RailCrew Switch Machine Connect 1 to Red wire
Connect 2 to Black wire		 Bypass 12 V Breakout Board, or
RailCrew Switch Machine		 Breakout Board RailCrew Wiring (PDF)
DCCconcepts Cobalt Omega, Cobalt iP Analog, or Cobalt Classic Point Motor Connect 1 to S2-L & S3-C connections
Connect 2 to S2-C & S3-R connections		 Bypass 9V, 12 V Breakout Board, or
Cobalt Classic Omega Point Motor, Cobalt iP Analog, or Cobalt Classic Point Motor		 Breakout Board Cobalt Omega Wiring (PDF)
Cobalt iP Analog
Cobalt Classic Wiring (PDF)
Since motor control lines are bidirectional, wire to switch machine for both directions
Walters® Walters Controls Switch Machine 942-101 Connect 1 to one IN connection
Connect 2 to other IN connection		 Bypass 12 V Breakout Board, or
942-101 Switch Machine		 Breakout Board 942-101 Wiring (PDF)
Configures for Polarity Route Option in support of bidirectional current
Model Railroad Control Systems MP4, MP5, MP10 Connect 1 to M1 connection
Connect 2 to M2 connection		 Bypass 9V, 12 V Breakout Board, or
MRCS MP4, MP5, MP10		 Breakout Board MP4 Wiring (PDF)
MP5 Wiring (PDF)
MP10 Wiring (PDF)
For MP1 & MP5, use Turnout Twin Coils Switch Machine Breakout Board
  1. To produce LCC Events, the breakout board is must be used since the switch machine itself is not integrated with LCC.
## Terminology

For other terms, please refer to the full Terminology Guide.

Assembly and Component Placement

This section combines both the component specifications and the assembly instructions to ensure a smooth assembly process. Below is a comprehensive list of components, their placement on the PCB, and orientation details to assist you during assembly.

High-Level Steps for Assembly:

Print PCB Turnout Slow Motion Switch Machine Breakout Board PCB
Print
Component Identifier Count Type Value Package Purpose Orientation
Capacitors            
C1, C3 2 Capacitor-Ceramic 47uF, 50 V 1206 X7R Used to smooth voltage/current changes from relay Slow_Motions None
C2, C4 2 Capacitor-Ceramic 0.1uF, 50 V 1206 X7R Used to reduce voltage spikes from relay coils None
C5, C9 2 Capacitor-Polymer Solid 100µF, 35 V 6.3x5.8mm SMD Used by 5V voltage regulator for input filtering. Anode positioned toward PCB top edge
C6, C10 2 Capacitor-Ceramic 0.33 uF, 50 V 1206 X7R Used by 5V voltage regulator for input filtering. None
C7, C11 2 Capacitor-Ceramic 22uF, 50 V 1206 X7R Used by 5V voltage regulator for output filtering. None
C8, C12 2 Capacitor-Ceramic 0.1 uF, 50 V 1206 X7R Used by 5V voltage regulator for output filtering. None
Diodes            
D1 - D6 6 Diode-Schottky SS310 SMD Circuit protection against flyback from motors and coils. Position cathode end (white line) to PCB top edge
D7 - D8 2 Diode-Schottky SS310 SMD Forces bidirectional motor current to flow only one way to LM7805 voltage regulator Position cathode end (white line) to PCB left edge
Fuses & Protection            
F1, F2 2 Fuse-PTC Polymer JK30, 3A, 16 V (or more) 5.1mm pitch, PTH Protects from sustained overcurrent conditions on frog None
Connectors            
J1 1 JST XH Socket 2P, 2.54mm PTH or Spring Term Connector to turnout frog Position connection outward
J2, J3 2 JST XH Socket 2P, 2.54mm PTH or Spring Term Connector to motor(s) Position connection outward
J4 1 JST XH Socket 2P, 2.54mm PTH or Spring Term Connector to track power rails (Rail A and Rail B) Position connection outward
J5 1 RJ45 socket 8P8C PTH Network cable (CAT5/6) connection from Turnout Card. Fits only one way
Selectors            
JP1, JP2 2 Male Header 2-Pin PTH Used to bypass current limiting resistor (R1,R2) to the motor. None
Resistors            
R1, R2 2 Resistor 220Ω 1206 SMD Limit current to motor, adjust value based on stall motor requirements. None
Relays            
K1, K2 2 Relay DPST, Non-Latching (Stable) TQ2-5V (PTH) Controls track Rail A and Rail B to frog and Point Sense line to ground Position IC’s small dimple in corner (pin 1) towards PCB top edge
Voltage Regulators            
VR1, VR2 2 Voltage Regulator LM7805CV TO-220, SMD Provides 5V power to NE555 timer and servo motor(s). Position heat sink towards PCB top edge

Tools Required

List of recommended tools.

Safety Precautions

Testing and Verification

Visual Inspection

  1. Initial Check: Examine the board for any obvious issues like missing components, solder bridges, or components that are misaligned or not fully seated.
  2. Solder Joint Inspection: Use a magnifying glass or a microscope to inspect solder joints. Look for cold solder joints, insufficient or excessive solder, or any shorts between pads.

Functional Testing

Troubleshooting

Appendences

Specifications

Specifications for the Turnout Slow Motion Switch Machine Breakout Board include:

Characteristic Value
Output 9V, 12 V1
Max Turnouts 2
Minimum Current ~30–180 mA2
  1. Output voltage is determined by the motor output voltage selection found on the Turnout Card.
  2. About 30mA when relay has been set to switch frog polarity. Max of 180mA when switch machine is moving the points, and relay has been set.

How It Works

The ** Turnout Slow Motion Switch Machine Breakout Board ** is designed to interface with the ** Turnout Card ** to control slow-motion stall motors for managing turnout points, while also controlling the frog polarity based on turnout position. The board enables bidirectional motor control and uses relays to switch the frog between Rail A and Rail B of the track bus, ensuring proper electrical continuity as the turnout moves between the Thrown and Closed positions.

  1. Inputs and Outputs Connections:

    • Input (Control Signals):
      • The board receives control signals from the Turnout Card via two input lines that handle the bidirectional motor control. Based on the Turnout Card motor output selection, motor control signals are 9V or 12 V outputs that set the motor’s direction to move the turnout points to either Thrown or Closed.
    • Motor Output:
      • Two motor output terminals connect directly to the slow-motion stall motor. The motor is driven in one direction or the other depending on the polarity of the control signals.
      • The board includes current limiting resistors to control current to the motors. Use the motor’s documentation to determine the correct amount of current to the motor.
      • The board also includes optional protection using polyfuse (resettable, PPTCs) on the motor control lines to protect against overcurrent conditions that could damage the driver circuitry.

  2. Bidirectional Motor Control:

    • The Turnout Card controls the motor direction. Depending on the control signal:
      • One polarity drives the motor in the direction to set the turnout to the Thrown position.
      • The reverse polarity drives the motor in the direction to set the turnout to the Closed position.
    • As the control signals are received from the LCC Fusion Node Card firmware, the Turnout Card MCP23017 GPIO switches between high and low states and uses a TC4428 to drive the motor, moving the turnout points to the required position.

  3. Relays for Frog Polarity Control:

    • The Turnout Slow Motion Switch Machine Breakout Board uses a mechanical relay to control the frog polarity. The relay switches the frog’s connection between Rail A and Rail B based on the position of the turnout.
    • This ensures that the frog always has the correct polarity based on the turnout’s position, providing smooth operation and preventing short circuits as the train moves through the turnout.

Connections

The purpose of the Turnout Servo Switch Machine Breakout Board and its connectors is to facilitate quick and easy connections between the Turnout Card and a turnout controlled by a servo.

Component Designator **Connector Label ** Connector Type Connection Number Description
J1 ACC GND JST XH, Spring Terminal GND Connection to the layouts accessory bus or dedicated power supply (not to DCC). GND must connected to the same ground plane as the LCC Fusion Node Card.
J2 FROGS JST XH, Spring Terminal 1, 2 Connection to power turnout frogs
J3, J4 MOTOR 1 / MOTOR 2 JST XH, Spring Terminal 1, 2 Connection to switch machine. Note the current is bidirectional.
J5 TRACK BUS JST XH, Spring Terminal A, B Connections to the layout track bus for Rail A and Rail B. Used to power the frog when. If necessary, switch the connections to match the frog to the correct rail.
J6 TURNOUT CARD RJ45 Socket 1 - 8 Refer to Turnout Card’s connection table for the function of each pin

Protection

Protected Component Protection Component Function Specifications Location
Entire Circuit PPTC Polyfuse Protects from sustained overcurrent conditions by increasing resistance when the current exceeds 0.25A (250 mA). Resets once the fault condition is cleared. Hold Current: 0.25A
Trip Current: 0.5A		 In series with the motor’s Vcc line. Adjust the fuse type to match the max current expected by the stall motor.
Track Power PPTC Polyfuse Protects from sustained overcurrent conditions by increasing resistance. Resets once the fault condition is cleared. Fuse Rating: Based on max track current (typically 0.5-3.5A depending on track power). In series with the track power supply, between the power source and the track.
Relay Coils, Stall Motors Flyback Diode Protects the circuit from high-voltage spikes caused by inductive loads (relay coils, stall motors) when switching off. Diode Type: Schottky
Max Current: Min 0.5A
Reverse Voltage: Min 12 V		 Across the relay coil or stall motor terminals (one diode for each direction in bidirectional motor circuits).
LM7805CV Regulator Capacitors (Input/Output) Stabilizes voltage and reduces noise on the input and output of the voltage regulator. Input Cap: 0.33µF
Output Cap: 0.1µF		 Input cap across the input pin and GND. Output cap across the output pin and GND.
Stall Motor Current-Limiting Resistor Limits the current flowing through the stall motor to prevent damage or overheating. Resistor value is determined by the stall motor’s voltage and current rating. In series with the stall motor, resistor size based on motor specifications.
Entire Circuit Reverse Polarity Protects the entire circuit against reverse polarity by becoming forward-biased when the power supply is connected backward, effectively short-circuiting the supply and blowing the fuse to protect the circuit. Diode Type: Schottky
Max Current: Min 0.5A
Reverse Voltage: Min 12 V		 In series with ACC GND

References

Last updated on: May 10, 2025 © 2025 Pat Fleming