Technology Connections
6 HN recommenders · recommended in 8 months, 2020–2025
11:11 · 3.2M views · Jan 15, 2020
Technology Connections explains how old-fashioned non-electronic rice cookers work, using a magnet and spring switch tripped by the Curie point. It shows the thermodynamics and magnetism behind a simple appliance.
HN recommends it as a delightful breakdown of the cleverness in dumb appliances and an entry point to the channel.
8 comments from Hacker News
Have I got the channel for you! Technology Connections: [LINK] . My introduction was his rice-cooker video: this video .
The science behind a rice cooker is fascinatingly clever, yet painfully simple. In short, boiling water temperature plateaus due to the latent heat of vaporization. When the water is gone the temperature of the pot starts to rise. The rice cooker uses this principle to control the switch. The switch is held by magnet. When the pot finishes boiling the heat rises and exceeds the curie point of the magnet, which means the magnet ceases to be magnetic, and the (no longer) magnetic switch is released turning the rice cooker off. Here’s a great video explaining how it works. this video
I have a basic rice cooker and I absolutely love it. Perfect rice every time without having to think too hard about measurements or the time, as the measurements are stamped on the bowl (fill rice here, fill water here) and it will always switch to warming mode at exactly the right time. I wouldn't bother getting a fancy computerized model, the old thermostatic ones are pretty much perfect. Technology Connections video on old-style rice cookers: this video We have that exact same kettle, its wonderful.
I started using the old-fashioned analogue rice cooker after watching Technology Connection's video on how they work. The principle is clever: liquids at boiling point stay at boiling point, since any additional heat energy is used to change their state from liquid to gas. When the temperature does rise above 100°C, that means there is no liquid left in the cooker, and so rice must be done. It then switches off the high heat and runs in "warm" mode. 1. this video
> weight/balance mechanism in a traditional "dumb" rice cooker These are far more interesting than that. Technology Connections YouTube channel did a great breakdown of how they really work: this video