Smoke alarm printer power shutdown

thingiverse

Do at your own risk project, as I didn't conduct thorough research on all the hardware. For example, the smoke alarm is tripling the voltage input and sending 8v into the 3v relay trigger, and I'm unsure what the relay trigger chip range is specified to run at. A variation of the HenryArnold smoke sensor power killer. Hopefully, there will be smoke before the printer catches on fire, and this setup should shut down the power supplies. Fairly simple configuration: a smoke alarm that outputs some voltage to trigger a relay which interrupts the power supplies on circuit. Although this works, I'm a bit confused about what's happening with the voltage output. I input 3.3v into the smoke alarm, but it appears to be stepping up the voltage to 9.x volts. 6/16/19: Installed two relays to add latching function. I tried a couple of relays that claimed to be latching but they worked by toggling on and off with a flip flop chip. It might be possible to simplify this circuit just using a single-double pole relay powered directly from the smoke alarm, but I didn't test it as I wasn't aware of the current output capability of the alarm. I connected the smoke alarm to one of these IoT relays: https://www.amazon.com/Iot-Relay-Enclosed-High-Power-Raspberry/dp/B00WV7GMA2 The smoke detector used is First Alert BRK 3120B, available at https://www.amazon.com (search for "B00O8MVW44") Small relays used inside the smoke alarm: https://www.amazon.com/gp/product/B07L6JXGXV/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1 5v to 3.3v regulator: https://www.amazon.com/gp/product/B074FDLCLB/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1