I liked Henry Arnold's 3D Printer Safety Shutdown system, but I wanted to use multiple smoke detectors in my two-level enclosure. This remix includes a printed circuit board to add multiple inputs to the system.
I designed a PCB that replaces the in-line diodes. The PCB is very simple and uses 8 diodes for 8 possible inputs to the shutoff relay. The PCB uses screw terminals to attach the input and output wires, and is fastened with M3 screws.
I designed the PCB in KiCad, and submitted the attached "Smoke Alarm PCB.kicad_pcb" to OSH Park. The cost was only about $15 for three boards, which was surprisingly affordable.
DO41 Diodes - Qty 8 (ex 641-1310-1-ND from Digi-Key)
Two Position 0.10" Terminal Block - Qty 1 (ED10561-ND from Digi-Key)
Eight Position 0.10" Terminal Block - Qty 2 (ED10566-ND from Digi-Key)
I've also included two STL's for the PCB enclosure and enclosure lid. I built the enclosure with M3 heat-set inserts to hold the lid fasteners.
Finally, I designed a taller mount for the smoke alarm mounting. It's a simple spacer with a large wire outlet.
For more photos and details, check out my write-up here: https://grahamjessup.com/smoke-alarm-shutdown/