MQTT WiFi Turnout Controller

The circuit has a very few components:

  • TB1 & TB2 – 8 contact terminal blocks to connect to the Tortoise motors (4)
  • TB3 & TB4 – 3 contact terminal blocks for power 5 and 12v and ground
  • U1 – the ESP8266 component
  • U2 – the MCP23017 component a 16-Bit I/O Expander with Serial Interface
  • U3 & U4 – L293D Quadruple Half-H Drivers
  • C1 & C3 – 33uf 16v capacitors
  • C2 & C4 – 0.1uf capacitors

The follow schematic shows the circuit

The PCB design can be found in the RAILS-HW project onmy GitHub repository
The source code for the ESP8266 can be found in the RAILS-Micro project on my GitHub repository