My DIY Soldering Station Build

Built a T12 cartridge soldering station for about $25 in parts. The T12 system has a thermocouple integrated into the tip, which gives direct feedback and far better temperature control than a thermostat-in-the-handle design.

The control board uses an STM32F103 (Blue Pill module) with a zero-crossing detector, TRIAC for AC power control, and a thermocouple amplifier for the T12 cartridge. The PID loop runs at 10Hz — slow enough that the thermal mass of the tip averages out noise but fast enough to prevent overshoot.

I compared tip temperature accuracy against a type-K thermocouple stuck to the tip: within ±5°C at all setpoints from 200-450°C. Commercial stations claim ±2°C but they're comparing against their own calibration. The real-world performance of this build is indistinguishable from a $200 Hakko FX-951.