About 30 KHz. Varies, but hundreds of watts.
See .
He publishes his circuits.
He was a founder of Fluxeon: .
Joe Gwinn
I don't know that one in detail, but I would guess 50-200kHz and under 1kW. And at a Q up to 10 or so, probably.
Reactive power is a huge performance factor for induction heating: it's how much distance you can have between coil and work, and what kind of materials you can heat. Same performance factor as wireless charging and whatnot, and for the same reason -- you need to resonate out all the leakage inductance between coil and work.
Low Q is basically only for tight fitting coils and ferrous metals up to (or maybe a little bit beyond) Curie temperature. Great for loosening bolts, not so great for say, brazing carbide.
And not nearly enough power for, say, case hardening, or levitation melting, if you want to get into specialized applications.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
On a sunny day (Sat, 1 Aug 2020 16:32:35 -0400) it happened bitrex wrote in :
Yea, I have one like that from ebay, used for many experiments. Even baking eggs.
Those things have a nice clean sinewave output.
Useful for many things:
I'd second these things. The only goofy part is if the input voltage gets too low (maybe 10 or even 11 volts) they latch up. So, if you try to run it off a 12 volt lead acid battery, you have a good chance of the thing running poorly on a weak battery or with power cables that are too thin. It's obvious when it latches up too- the output stops and the heatsinks get burning hot real fast. They normally run cool enough to touch. The copper inductor will heat up fast if you have no load as well.
Frequency depends on the size of the object to be heated, and if one is trying to heat only the surface, or to go deeper.
The INIMD-700A mentioned above is for loosening bolts and expanding bearing races in an auto repair shop, so its frequency will be lowish. Was it 50 KHz? I think I saw that somewhere.
Yes to all. Neon John recommended a book from the industrial world on all such things:
"Elements of Induction Heating -- Design, Control, and Applications", S. Zinn and S. L. Semiatin, EPRI, ASM International, 1988, 35 pages, ISBN 0-87170-308-4. This book was commissioned by EPRI.
This cost $35 on Amazon in 2017; the price is more like $100 now, and I assume that it's now out of print. My copy is from the Fifth Printing in March 1998.
Joe Gwinn
Neon John used to be a regular here. He moved into an assisted-living place back in February and hasn't posted since. Hope he's OK.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
In an optimized application, yes -- I highly doubt they are so discerning, and they certainly can't afford to run the frequency too low ( "Elements of Induction Heating -- Design, Control, and Applications",
Yup, very informative.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
I do remember when he posted, and then (if I recall) his health started to fail, and he retired. I don't know if he is OK. Does anybody know?
Joe Gwinn
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