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Cooker throttles when water boils

  1. Oct 19, 2012 #1
    Hello everybody!

    I'd like the cookers to reduce and adjust their power automatically when the liquid in the pan starts to boil, or the oil in the frying pan. Induction cookers, and some others, react quickly enough for it.

    Maybe they exist already? I suggested it to a Spanish company in 1996.

    I imagine the sensor could listen to the noise injected by the pan or frying pan in the cooker. Something like a wire could transmit the mechanical noise from the hot area to the vibration sensor working at cool temperature.

    Then, electronics could first filter the high frequencies or sharp transitions associated with bubbles, then either count the bubbles per time unit or evaluate the strength of the bubble noise, to inform the regulator circuit.

    Marc Schaefer, aka Enthalpy
     
  2. jcsd
  3. Oct 19, 2012 #2
    Interesting concept - a audible/vibration feedback for cooktop...... like a preheat and it goes to 50% power when activated?

    Doable...
     
  4. Oct 20, 2012 #3

    mfb

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    I don't think vibrations are a good idea - you can get the first bubbles on the bottom long before the whole thing boils (and before convection establishes), and you can get noise from other sources.

    What about a simple thermistor (temperature-dependent resistor)? For water only, you can measure the absolute temperature. If all boiling things should be considered, measure the time-derivative of the temperature: If the temperature curve flattens, reduce power.
     
  5. Oct 21, 2012 #4
    Whether water boils gently or too strongly, it will be at +100°C equally, so its temperature tells nothing at all... And the top plate of the cooker, which is a bad heat conductor in induction or in infrared cookers, doesn't even represent the pan's temperature.

    That's why the temperature is the wrong choice.

    As for bubble noise, humans can analyze it from a distance, so the cooker having first-hand signals must achieve it. It needs some trials to define the proper signal treatment.
     
  6. Oct 21, 2012 #5
    I bought an induction hob with a constant temp setting for frying or boiling in 2000 or thereabouts.

    The instructions say that the control system works on temperature.

    It works well.
     
  7. Oct 21, 2012 #6
    OK then, leave other people developing the one based on noise.
     
  8. Oct 21, 2012 #7

    mfb

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    This is just a rough approximation. Temperature measurements are very precise.

    And what about the boiling water nearby?
    Humans have an excellent pattern recognition - better than modern computer software.
     
  9. Oct 21, 2012 #8
    Actually, I was not in any way trying to detract from your idea. If you have genuinely invented a new way to control the cooking I would be the first to congratulate you.

    My comment should let you know that there is a market out there for any method that works and is cost effictive.

    That, sir, is valuable commercial information.

    However I would also observe that your method of discussion invites opposition.

    If you were to ameliorate your style I suggest you would learn more and be listened to more.

    go well
     
  10. Oct 21, 2012 #9

    sophiecentaur

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    You could, alternatively, use a sealed top on the pan and detect a sudden increase in pressure as the liquid boils. Trouble with that is the requirement for telemetry. A temperature sense / control could be made much more sophisticated by looking at the rate of temperature increase and an actual contact thermometer. I believe I have seen a sort of sprung temperature sensor in the middle of the ring on an ancient cooker.

    You often want maximum power for a while, until the liquid reaches a specific temperature and then to back off before boiling sets in so more machine intelligence could help. However, I must say, since I started using a gas ring, all this is much less of a problem.

    Btw, something I want to see is a stirring mechanism for liquids in a microwave oven - that would also stop unwanted local boiling.
     
  11. Oct 21, 2012 #10
    Perhaps the makers of non metallic ceramic guns, so beloved of spy stories, could turn their hands to something more useful and produce a clockwork one?

    I have the money waiting to buy one.

    :wink:
     
  12. Oct 21, 2012 #11

    sophiecentaur

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    I did consider gluing an anchor point in the roof of the oven and hanging a paddle from it. As the bowl rotates, the contents would get a mild stirring. But I like the James Bond solution more.
     
  13. Nov 11, 2012 #12
    As a sensor for boiling water or oil, I thought naturally of piezo sensors for acceleration or force, but a pickup microphone as on an electric guitar is an interesting option.
     
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