This is a project of an alternative SH72 soldering iron controller with turbo mode, two-stage sleep mode, grounding the soldering iron tip to a "-" power wire and the protection against the reverse polarity, short circuit and overvoltage.

The original circuit was taken as a basis, additional functions were implemented on the ATtiny13(A) microcontroller. Thanks to this, when upgrading the soldering iron, most of the components for this controller can be taken from the original board. 

When ordering board, you should choose the FR-4 core with a thickness of 1.2 mm.

Due to the lack of free space on the board, the programming connector was not installed. Therefore, it is necessary to program the microcontroller before installing it into the board or connect the programmer cable by soldering it to the following pins: 1 - RESET, 4 - GND, 5 - MOSI, 6 - MISO, 7 - SCK, 8 - VCC.

Warning! Be careful when powering the MCU from a programmer or external source, as the MCU power is shunted by a parallel voltage regulator (DA1, 5V)! Also during the programming of the MCU, the position sensor (SW2) should be disconnected and turbo button (SW1) should be released!

Despite the fact that the DA1 stabilizer on the original board is marked as 431, but its pinout corresponds to the 432. Based on this, the DA1 stabilizer is marked in the diagram and installed on the board as 432.

Do not install R4, R5 if original LED used.

The firmware of the microcontroller was designed in such a way as to use the factory-setted fuse bits, only the flash memory of the programs needs to be flashed in the new MCU.

At the moment, the board and MCU firmware have been developed, but not tested yet, since the boards have not arrived from the factory yet.

UPD: controller is assembled, need to test / debug

UPD: firmware behavior tested with low power (external 5V only), need to test with full power