SDG #358 AxxSolder - Open Source JBC Soldering System

AxxSolder is an open source soldering station controller designed to drive JBC C115, C210 and C245 cartridges, published on GitHub with the PCB, firmware and mechanical CAD. The same board serves the portable unit reviewed here, with a TFT, an encoder, two preset buttons and a small metal rest that triggers standby, or a bench version that mounts on a genuine JBC cradle. Power comes from USB-C Power Delivery or a DC input, and an earth terminal grounds the tip. A fully assembled unit is sold on Tindie for $145 and the bare PCB for $10, and the design is on PCBWay’s shared projects page for PCB, assembly and 3D printed housing orders.

The schematic uses a high side gate driver and N channel MOSFET on the heater, a switching regulator feeding a 3.3 V LDO, a USB PD controller, and an STM32 with separate analogue stages for current feedback and the thermocouple. Two points in the thermocouple amplifier deserve attention: a high gain chopper stabilised op amp with no feedback capacitor to limit its bandwidth, and a capacitor directly on the op amp output, which risks oscillation without a series resistor.

The station negotiated 20 V from a 300 W USB-C supply but limited itself to 100 W; from a 24 V bench supply it heated far faster, drawing about 5.5 A, and put around 75 W into a coin test. Firmware 3.3.1 was loaded over USB in DFU mode using STM32CubeProgrammer. The menu includes standby and sleep timers, a power limit, multi point calibration, an extractor output and a serial debug stream for PID tuning. Suggested improvements are a long press to store presets and menu access without a power cycle, and since the portable rest is easily knocked, the cradle version suits a bench better.