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Comment by benoliver999 | Hacker News Reader

I do think I could use an upgrade though, my induction hub just clicks on and off PWM style. Not great for a steady heat.

Having read this article I noticed that they aren't all like this.

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It may be that your cookware is no good. For safety reasons all control systems for induction appliances have a feature to automatically turn off when they detect that the generated field is not being received by a large enough target surface, since otherwise it would be a fire risk. Try changing cookware, you may find the issue goes away.

It's across all my cookware. Pans, cast iron, the coffee maker, the kettle.

If I put it on full power, then it's a continuous blast of energy and it never clicks off. That's great for boiling water but not much else.

If I put it on 70%, it goes on full power for 7 seconds, then stops for 3, then back on for 7 etc etc.

Are you sure you don’t have a normal electric stove?

Yes, it won't work without a pan on it. Doesn't work with aluminium. Is relatively cold to the touch despite having just been used to boil a kettle. Says 'Induction Hob' on it.

An induction cooktop with bang-bang control? I guess that is definitely something to look out for and avoid: https://www.avforums.com/threads/are-there-different-types-o...

It's a smeg if anyone reads this and cares. Probably quite cheap; the previous owner put it in to help sell the house

Can absolutely recommend the upgrade, these stoves are far superior to PWM style "2000W or off" ones. I can even melt chocolate without a water bath on mine, they can keep temperatures as low as 55°C / 131°F steadily no problem. :D

I just have to be pedantic and say that what you are describing is the very opposite of PWM, which runs at high frequencies (e.g. 30kHz), varying the duty cycle over the tiny slice of time. The only problem with good PWM is audible harmonics, usually only children can hear them.

I disagree. The definition of what is high and what is low frequency depends on what you are comparing.

If you are comparing electric capacitances of electric circuits vs the thermal capacitance of a macroscopic object, 1 Hz might be a high enough frequency for doing pwm.

Also, the 'exact opposite' would simply be a gas hob. Yeah you might not call something that clicks on and off every 10 seconds 'PWM' but it's not that far removed

> I just have to be pedantic and say that what you are describing is the very opposite of PWM, which runs at high frequencies (e.g. 30kHz), varying the duty cycle over the tiny slice of time.

Yes, this is correct. What parent is describing is generally referred to as bang-bang control [1].

[1] https://en.m.wikipedia.org/wiki/Bang–bang_control

Those whines drive me crazy and I’m 34! Do any induction cooktops not have that terrible whine? At least with the duxtop portable induction I had to return it because the whine was so bad.

Which leads to the question : which ones do not have a whine? Does the breville? Or which? It’s not something any reviews I’ve seen talk about

They can work at frequencies and with electronic designs that are far out into the ultrasonic range.

You may want to check out those that apparently can handle non-magnetic cookware; those apparently run on higher frequencies to make up for the weaker magnetic effect.

Cool! What are examples of this? It’s really hard to find the data sheets for these. Or at least I couldn’t

Ah, you're right, thank you! I just reused the words of the parent :D

To be even more pedantic, the grandparent could absolutely be describing PWM - PWM is pulse width modulation - it means that there's a fundamental frequency, and within each cycle the stove is "on" for a period and "off" for the rest. The "on" period length is varied (modulated) based on the power requirement.

What "PWM" doesn't define is the fundamental frequency. It could be 0.1 Hz or 10 MHz. Just because the fundamental frequency is slow doesn't make it not PWM.

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