Magnetic Levitation Using An Induction Cooktop

Adding another item on the list of things you probably shouldn’t be trying at home, we got [Brainiac75] giving magnetic levitation a shot using an unmodified induction cooktop and aluminium foil. Although not ferromagnetic, it turns out that aluminium can be made to do interesting things in the magnetic field created by the powerful electromagnet that underlies the induction principle.

Interestingly, although there’s a detection circuit in these units that should detect the presence of an appropriate (ferromagnetic) object, it appears that even a thin sheet of aluminium foil can completely deceive it. The effect is that of a force pushing the foil away from the cooktop’s surface, with foil areas that remain close enough to the ferrite bars on the electromagnet even heating up enough to begin melting the aluminium.

After a bit of fun with various shapes and types of aluminium objects, the video moves on to a scientific explanation of what’s going on. The surface resistivity of the foil is similar enough to ferromagnetic cookware that it fools the sensor, after which the skin effect of aluminium induces a current. This then does the typical Lorentz force things.

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Cooking With Magnets And 3D Printing

Have you ever wondered how induction cooking works? A rotating magnetic field — electrically or mechanically — induces eddy currents in aluminum and that generates heat. When [3D Sage] learned this, he decided to try to 3D print some mechanical rigs to spin magnets so he could try cooking with them.

We doubt at all that this is practical, but we have to admit it is fun and there are some pretty impressive 3D prints in the video, too. The cook surface, by the way, is tiny, so you won’t be prepping a holiday meal on it. But there’s something super charming about the tiny breakfast on a plate produced by a printed magnetic “stove.” We would be interested to know how much power this setup consumed and how much heat was produced compared to, say, just using a big resistor to heat things up.

We’ve heard that induction heating is efficient, but this setup is a bit unconventional. If cooking things isn’t your bag, you can use induction for soldering, too.

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Ceramic stove (credit: Felix Reimann)

Same Taste With Less Energy: Optimizing The Way We Cook Food

Preparing food is the fourth most energy-intensive activity in a household. While there has been a lot of effort on the first three — space heating, water heating, and electrical appliances — most houses still use stoves and ovens that are not too dissimilar to those from half a century ago.

More recent technologies that make cooking more efficient and pleasant have been developed, such as induction heating. Other well-known and common appliances are secretly power savers: microwaves and electric kettles. In addition, pressure cookers enable the shortening of cooking times, and for those who like dishes that take hours to simmer, vacuum-insulated pans can be a real energy-saver.

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DIY Induction Soldering Iron

[Kasyan TV] shows us how to make a really simple DIY induction soldering iron complete with DIY soldering tips.

This is a pretty cool project. Most of us are used to temperature controlled ceramic heating elements, but there are other ways to get those irons up to temperature. Using scraps from older, presumably broken, soldering irons and some pieces of copper and iron along with a thermocouple for temperature management, [Kasyan TV] manages to throw together an Inductively heated soldering iron. To insulate the coil from the iron they use Kapton tape. The video goes on to show how to make your own induction iron, although missing is a power supply. We are sure a quick eBay search for an induction heater module should bring up something suitable to power the iron, or you could just wait and watch the their next video that will go over power supplies. The soldering tips are simply made from thick copper wire sculpted into the correct shape.

There are advantages to using a soldering iron like this, for example they are pretty durable and will take a knock or two, Our concern is that magnetically sensitive parts may not be happy, and the iron might destroy what you are trying to build. Either way we’ve put the video below the break, so take a look.

Hackaday has featured a few different DIY soldering irons and some pretty cool DIY Soldering Stations over the years. What is your soldering iron of choice and why?

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Reactor Forge Promises Induction Heating For All

Ever want to try your hand at black smithing? Building a forge is expensive and tricky — especially if you live in an apartment! But we’re all tech nerds here — it’s way cooler to use induction heating to heat up your metal for forging. Fire is for cavemen! [Josh Campbell] is working on a kit to bring induction heating to the masses — he calls it the Reactor Forge.

The kit hasn’t launched yet, but you can follow his progress on his GitHub. Induction heating works by magnetically inducing current into the metal, where resistance turns the current into heat without physical contact. The Reactor Forge [Josh] has built runs off of a 220V circuit, and in the following demonstration, heats up a 6″ section of 1/2″ steel bar.

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A Small, 1000W Induction Heater

[Proto G] built a small, desktop induction heater that is capable of making small castings, melting small amounts of metal, and functioning as one of the best solder pots we’ve ever seen.

The induction heater is built from a custom Zero Voltage Switching (ZVS) driver and powered by a small 48V, 1000W power supply. While this makes for an exceptionally small induction heater, it’s still very capable. In the video below, it only takes a few seconds to heat a screwdriver up to a temperature that will melt solder.

While an induction heating machine is essentially useless for irons unless you have a few antique, unpowered, blowtorch-powered soldering irons, it does make for a great solder pot. [Proto G] replaced the working coil in his induction heater with litz wire. The actual solder pot is made out of steel conduit wrapped with aerogel-infused fiberglass insulation. Compared to his old solder pot, this machine heats up instantly, and is more than capable of wetting a few wire connections.

The future plan for this inductive heater is to make a few more attachments for different metals, and a [Proto G] has a few aerogel blankets he could use to make some small metal castings.

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3D Printering: Induction Heating

Every filament-based 3D printer you’ll find today heats plastic with resistive heaters – either heater cartridges or big ‘ol power resistors. It’s efficient, but that will only get you so far. Given these heaters can suck down only so many Watts, they can only heat up so fast. That’s a problem, and if you’re trying to make a fast printer, it’s also a limitation.

Instead of dumping 12 or 24 VDC into a resistive heater, induction heaters passes high-frequency AC through a wire that’s inductively coupled to a core. It’s also very efficient, but it’s also very fast. No high-temperature insulation is required, and if it’s designed right, there’s less thermal mass. All great properties for fast heating of plastic.

A few years ago, [SB] over on the RepRap blog designed an induction heater for a Master’s project. The hot end was a normal brass nozzle attached to a mild steel sleeve. A laminated core was attached to the hot end, and an induction coil wrapped around the core. It worked, but there wasn’t any real progress for turning this into a proper nozzle and hot end. It was, after all, just a project.

Finally, after several years, people are squirting plastic out of an induction heated nozzle. [Z], or [Bulent Unalmis], posted a project to the RepRap forums where he is extruding plastic that has been heated with an induction heater. It’s a direct drive system, and mechanically, it’s a simpler system than the fancy hot ends we’re using now.

Electronically, it’s much more complex. While the electronics for a resistive heater are just a beefy power supply and a MOSFET, [Z] is using 160 kHz AC at 30 V. That’s a much more difficult circuit to stuff on a printer controller board.

This could be viewed as just a way of getting around the common 24V limitation of common controller boards; shove more power into a resistor, and it’s going to heat faster. This may not be the answer to hot ends that heat up quicker, but at the very least it’s a very neat project, and something we’d like to see more of.

You can see [Z]’s video demo of his inductive hot end below. Thanks [Matt] for the tip.

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