MQTT WiFi controlled mains halogen dimmer that can be controlled by rotary controller or from home automation (OpenHab) by PIC and ESP8266. The 300W halogen lamp is dimmed on the primary side of a round (conventional) transformer. The dimming electronics are decoupled from the mains for easy debugging. The zerocross signal is taken from the secondary side of a small transformer that also supplies the circuit with about 3.7V (old phone charger).
The mains part with the triac is now built on perfboard. Works fine. A small reallife test showed that it also works on the 300W halogen transformer. Had to pull an extra nullwire as it wasn't present at this location.