TS100 mini soldering iron

The TS100 soldering iron is an open source hardware by Miniware, which releases the schematics and software.  It has a decent construction; it comes with one tip but no power adapter.  The input voltage range is 12 to 24V, for power of 17W to 65W.  The interesting feature is that custom software can be loaded.  Ralim/ts100 on Github is an alternate firmware with more features.

The processor is STM32F103T8U6, 72MHz M3 core with 64K Flash and 20K SRAM, 2 12-b ADC.  It includes a 3-axis digital accelerometer for motion and orientation detection, 96x16 OLED display, a temperature sensor, TMP36 and two push buttons.  It has a barrel connector (5.5mm x 2.5mm) for power and a micro USB connector for firmware update.  The tip contains a thermocouple (reported to be type K); TMP36 provides the cold junction compensation.  The circuit design seems decent; it does not aim for the lowest cost possible.  For the price of about $50, it should not need to skimp on the circuitry.  I would estimate the bill of material costs do not exceed $20.  With 12V input, it takes about 30s to heat up to 300C; with 19V input (40W) from a laptop power adapter, it takes about 12s.

With the right firmware, it does make a nice soldering station.  The tip temperature is settable up to 450C.  The iron goes to sleep on a timer and wakes up on motion.   It can be made portable with a LiPo pack; the cutoff voltage is settable based on number of cells.  Because of the small size, a stand can be made out of a paper clip.