Technology Connections is generally awesome, but this particular video was even more fascinating than its usual.
Instead of a bimetallic switch like discussed earlier in this same HN thread, there's a lump of metal in contact with the pot, which stops being responsive to a magnet at a certain temperature (past its curie point) and that's what triggers the switch from "cook" to "keep warm" (and yes, of course it all works due to the huge latent heat of water).
So they came up with an alloy whose curie point is just above water's boiling point, and thanks to that, the circuit, nah, the whole thing is comically simple - just a shunt, a spring, a big resistor and the heating element (and ok a led or 2). The weight of the pot is also acting against the spring, ensuring you can't actually select "cook" if the pot isn't there. This is so brilliant.
Instead of a bimetallic switch like discussed earlier in this same HN thread, there's a lump of metal in contact with the pot, which stops being responsive to a magnet at a certain temperature (past its curie point) and that's what triggers the switch from "cook" to "keep warm" (and yes, of course it all works due to the huge latent heat of water).
So they came up with an alloy whose curie point is just above water's boiling point, and thanks to that, the circuit, nah, the whole thing is comically simple - just a shunt, a spring, a big resistor and the heating element (and ok a led or 2). The weight of the pot is also acting against the spring, ensuring you can't actually select "cook" if the pot isn't there. This is so brilliant.