Re: [Phys-L] Singing Kettle

[brian whatcott <betwys1@sbcglobal.net>]

Congratulations to Jeffrey for identifying a fruitful line of 
investigation. As it happened, my wife returned from a European trip two 
hours later, and almost immediately asked, "What's wrong with the 
kettle?    The power light is turning on and off."

In self defense, I should say that I am left handed, so the dim 
indicator light faces the wall when I handle the kettle.
I examined the clockwork, after defeating the anti-tamper precautions: 
fixing screws with a three-lobe indentation for a kind of three legged 
philips screw-driver, which I rendered amenable to the efforts of a 
straight-edge screwdriver, using a dremel.
The design layout was sparsely elegant - except the two pole switch was 
carried on long copper fingers, one of which was noticeably discolored 
and heating one of the several overheat thermostats enough to push the 
contact out of contact with the cooked fixed contact support.    After 
ordering a replacement on line - as most things are obtained, lately - I 
did what I could to renew my handiman cred by fixing the old one.

Thanks for spotting the issue Jeffrey!

Brian W



On 10/24/2018 2:06 PM, Jeffrey Schnick wrote:
> It would be easy to rule out a thermostat or heat-sensitive electrical fault by monitoring the current.
>
> > -----Original Message-----
> > From: Phys-l <phys-l-bounces@mail.phys-l.org> On Behalf Of brian whatcott
> > Sent: Wednesday, October 24, 2018 2:58 PM
> > To: prefered phys-l address <phys-l@phys-l.org>
> > Subject: [Phys-L] Singing Kettle
> >
> > We use an electric water kettle, made by Hamilton Beach; its capacity is
> > 1.7 liters, electrified through its fixed base plate supplying 1.5kilowatts. The
> > shape is a truncated parabola of revolution, focus up.
> > When half filled, it shows a distinct acoustic pattern when the heating
> > produces gas bubbles. The sound oscillates on a 10 second periodic time,
> > from silence to a quiet pink noise and back, never louder than 60 dBm. I
> > suppose there is a positive feedback loop of some kind.    Care to hazard a
> > guess?
> >
> > Brian W
> >
> >
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