Do you like your cup of tea to be cooled down to exactly 54 C, have a love for machining, and possess more than a little bit of a mad inventor bent? If so, then you have a lot in common with [Chronova Engineering]. In this video, we see him making a fully mechanical chime-ringing tea-temperature indicator – something we’d be tempted to do in silicon, but that’s admittedly pedestrian in comparison.
The (long) video starts off with making a DIY bimetallic strip out of titanium and brass, which it pretty fun. After some math, it is tested in a cup of hot water to ballpark the deflection. Fast-forward through twenty minutes of machining, and you get to the reveal: a tippy cup that drops a bearing onto a bell when the deflection backs off enough to indicate that the set temperature has been reached. Rube Goldberg would have been proud.
OK, so this is bonkers enough. But would you believe a bimetallic strip can be used as a voltage regulator? How many other wacky uses for this niche tech do you know?
Thanks [Itay] for the tip!
That “niche tech” I think is so widespread that most if not every single appliance contains at least one. Yes, bonkers. Would you believe it ?
Most resettable thermal cutoffs use a bimetallic component. How wacky.
It’s not wacky. A bimetallic switch is most reliable though, say compared to some chip or discrete transistor circuit. Some mains transient and the protection circuit is out and leaves the circuit unprotected. It’s cheaper too. I really appreciate and prefer such simple switch.
You could use it to automatically snuff out a candle after a given period of time
The thermostat in my house as well as my car uses a bimetal strip. It’s hardly wacky. Agreed this thing is cool, but it could have equally been built in the 1920s.
I’ve seen coiled bimetallic strips used to operate the on/off valve for centrifugally-pumped hydraulic fan clutches for radiator fans. Old ones had long lifetimes and stable operating characteristics, but new ones have such poor quality control that most of them are defective or unsuitable out of the box, either never disengaging (loud) or never engaging (ineffective).
Properly operating, they’re hard to beat: pulling multiple horsepower off of your engine belting is rather more effective than merely hundreds of watts of electric fan cooling.
For the unaware:
“Deflection (engineering)
In structural engineering, deflection is the degree to which a part of a long structural element (such as beam) is deformed laterally (in the direction transverse to its longitudinal axis) under a load. It may be quantified in terms of an angle (angular displacement) or a distance (linear displacement). A longitudinal deformation (in the direction of the axis) is called elongation.”