Simple Induction Heater Helps with Homebrew Shrink-Fitting

Machinists have a lot of neat shop tricks, but one especially interesting one is shrink-fitting tools. Shrink-fitting achieves an interference fit between tool and holder by creating a temperature difference between the two before assembly. Once everything returns to temperature, the two parts may as well be welded together.

The …read more

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The Easiest Way To Put Your Doorbell On The Internet

Thanks to low-cost WiFi enabled microcontrollers such as the ESP8266 and ESP32, it’s never been a better time to roll your own smart home system. But that doesn’t mean it isn’t daunting for new players. If you’re looking for an easy first project, putting your old school doorbell on the …read more

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Set Your Nuts (and Bolts) Free with this Induction Heater

[Amon] built an induction heater to break stuck bolts loose. If you work on cars, machines, or anything big and metal, sooner or later you’re going to run into stuck nuts and bolts. Getting them unstuck usually involves penetrating oil, heat from a torch, and cheater bars. Heat usually works …read more

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Cooking Eggs with Magnets in Motion

It’s probably always going to be easier to just find some dry wood and make a cooking fire, but if you’re ever in a real bind and just happen to have a bunch of magnets and a treadmill motor, this DIY induction cooktop could be your key to a hot breakfast.

For those not familiar with them, induction cooktops are a real thing. The idea stretches all the way back to the turn of the last century, and involves using a strong magnetic field to induce eddy currents in the metal of a cooking vessel. As [K&J Magnetics] explains, the …read more

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Is Your Wireless Charger Working?

It’s that time of year at which the Christmas lights are coming out of storage, isn’t it. Some modern seasonal rituals: untangling half a mile of fairy lights, and replacing a pile of CR2032 cells in LED candles.

[RobBest] had a solution to the latter, owning a set of nifty rechargeable LED candles that came with their own wireless charger. Sadly the charger wasn’t working quite as intended, as the indicator light to show when it had finished its cycle was always on. How could he indicate that the induction system was in operation?

His answer was to take a …read more

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Inductive Loop Vehicle Detector Gets Modernized

Much like George Lucas and the original Star Wars films, many of us may find that our passion projects are never quite finished, especially when new technology comes around or we just want to make some improvements for their own sake. [Muris] was featured a while back for a vehicle detecting circuit, but is back with some important upgrades to his project. (Which, luckily, do not include any horrible CGI aliens.)

For starters, the entire project has been reworked from the ground up. For anyone unfamiliar with the original project, the circuit detected a vehicle via an inductive loop and …read more

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Inventing The Induction Motor

When you think of who invented the induction motor, Nikola Tesla and Galileo Ferraris should come to mind. Though that could be a case of the squeaky wheel being the one that gets the grease. Those two were the ones who fought it out just when the infrastructure for these motors was being developed. Then again, Tesla played a huge part in inventing much of the technology behind that infrastructure.

Although they claimed to have invented it independently, nothing’s ever invented in a vacuum, and there was an interesting progression of both little guys and giants that came before them; …read more

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Fail of the Week: Magnetic Flow Measurement Gone Wrong

Physics gives us the basic tools needed to understand the universe, but turning theory into something useful is how engineers make their living. Pushing on that boundary is the subject of this week’s Fail of the Week, wherein we follow the travails of making a working magnetic flowmeter (YouTube, embedded below).

Theory suggests that measuring fluid flow should be simple. After all, sticking a magnetic paddle wheel into a fluid stream and counting pulses with a reed switch or Hall sensor is pretty straightforward, right? In this case, though, [Grady] of Practical Engineering starts out with a much more complicated …read more

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