Torch your home for $4. (with schematic)

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This smoke detector is particularly interesting because it doesn't use the normal dedicated control chip, but instead uses what appears to be a very cheap and common microcontroller.
I was reminded about this unit when Mike of the channel mikeselectricstuff mentioned he'd found a Chinese component supplier selling microcontrollers for 3 cents each (minimum of just 10). Better still, they do actually have an English manual and downloadable development environment. Sadly there doesn't appear to be a programming algorithm for the common universal programmers.
Here's a link to Dave's video:-
And a link to Mike's excellent channel:-
(It's really worth subscribing to.)
The microcontrollers are OTP devices (One Time Programmable) so you would wreck one with every version of the software you tested. But hey, they're 3 cents each. And for the final production run they would just be a common cheap component on the PCB.
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