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 … Continue reading MQTT WiFi Turnout Controller