Automatic Fume Extractor

Hack a cheap smoke detector to automatically extract smoke, carbon monoxide and solder fumes!

I’m currently doing a lot of PCB assembly in work and I find the soldering fumes irritate my eyes and lungs.Using a cheap smoke detector, we can use its piezo buzzer output to drive a MOSFET switched extractor fan. This same design could be used to ventilated a room in the event of a fire or if carbon monoxide is detected!

Parts needed
Full parts list in BOM attached.

P-channel power MOSFET (IRF9530)
NPN transistor (C549C)
Battery powered smoke detector (optical or ionisation)
9-12V @1A+ power supply or suitable battery
Bridge rectifier (4x general purpose diodes)
Assorted capacitors
Assorted resistors
Assorted diodes
Perf board to assemble circuit OR purchase pre-populated PCB
Hacking the smoke detector
The IC on the board is a Shanghai Belling BL59S10. This IC contains all functions needed to detect smoke, drive the piezoelectric buzzer and handle alarm interconnections.

Combined with an IR photoelectric chamber, this IC is used todetect smoke through receiving light scattered by tiny smoke particles going into the chamber.When smoke is detected, A burst of alarm sounds are generated by an external piezoelectricbuzzer driven by the push-pull output of this IC.’”


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