TrackLink V1 - Prototype for Dragon Railway Locomotive

Specifications

• Input Voltage: 5V–11V
• Microcontroller: ESP32-S3-MINI
  • Connectivity: WiFi, BLE, and ESPNOW
• Motor Driver: 2× DRV8212 brushed motor drivers
• Max Motor Current: 4A peak

• LED Driver: ULN2003 transistor array
  • LED Voltage: 5V (regulated via AMS117 LDO)
  • Max LED Current: Up to 500mA (suitable for LEDs; cannot drive solenoids)
• Servo Output: 2x (can also be used for neopixels)
• Audio Output: MAX98357 I2S amplifier

Additional Information

• Code for BLE control is available on GitHub : TrainControl_BLE

Design Intent

The TrackLink V1 was specifically designed to test the following components:

• MAX98357 I2S Amplifier: Evaluated for its sound quality (also to see if it even works).
• DRV8212 Motor Drivers: Tested to drive N20 motors of various voltage and RPM specifications with Dragon Railway locomotives.

This board served to test the performance of these components under real-world conditions.

Conclusion for Dragon Railway Locomotives

1. Motor Selection

   • The 3V N20 motor performs adequately with a single Li-ion cell (4.2V). One DRV8212 motor driver is sufficient to drive up to four motors, making the second driver unnecessary.

2. Amplifier Performance

   • The MAX98357 I2S amplifier has great sound quality, better than analog amplifiers (obviously) that are more susceptible to noise.

3. Voltage Range

   • A voltage range of 5V is sufficient since the motor operates effectively at low voltages.

4. Proposed Improvements for V2

   • Remove AMS117 5V LDO: When using single cell 5V LDO is not required, this will improve efficiency and reduce thermal issues.
   • Integrated LED Resistors: Current-limiting resistors will be added directly to the PCB, using a fixed resistance of 100Ω for simplicity. LED brightness will be controlled in software.
   • Battery Management and Protection: Add a proper charging circuit and reverse polarity protection for extra safety, especially for our beginner users.
   • Power Switch: Include a proper power switch with digital power-off functionality to prevent battery drain when the device is idle.

Final Thoughts

The testing phase for TrackLink V1 has been completed. While there are areas for improvement, the design itself has no hardware errors. This version is shared for educational purposes, as a reference for designers working on similar projects.

If you have questions or suggestions, feel free to share your feedback!