Category Archives: ac

Down the DIY Rabbit Hole with a Shop AC Installation

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There’s a fine line between a successful DIY project and one that ends in heartbreak. It’s subjective too; aside from projects that end up with fire trucks or ambulances in the driveway, what one DIYer would consider a disaster might be considered a great learning opportunity to someone else.

We’re pretty sure [Cressel] looks at his recent DIY mini-split AC installation for his shop as a series of teachable moments. Most folks leave HVAC work to the pros, but when you run a popular YouTube channel where you make your own lathe from scratch, you might be persuaded to give …read more

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A Dramatic Demo of AC Versus DC Switching

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Switches seem to be the simplest of electrical components – just two pieces of metal that can be positioned to either touch each other or not. As such it would seem that it shouldn’t matter whether a switch is used for AC or DC. While that’s an easy and understandable assumption, it can also be a dangerous one, as this demo of AC and DC switching dramatically reveals.

Using a very simple test setup, consisting of an electric heater for a load, a variac to control the voltage, and a homemade switch, [John Ward] walks us through the details of …read more

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Scrapped Motors Don’t Care About Direction

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Spinners built into games of chance like roulette or tabletop board games stop on a random number after being given a good spin. There is no trick, but they eventually rest because of friction, no matter how hard your siblings wind up for a game-winning turn. What if the spinning continued forever and there was no programming because there was no controller? [Ludic Science] shows us his method of making a perpetual spinner with nothing fancier than a scrapped hard disk drive motor and a transformer. His video can also be seen below the break.

Fair warning: this involves mains …read more

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Push Big Red Button, Receive Power.

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As with the age-old panic after realizing you have left an oven on, a candle lit, and so on, a soldering tool left on is a potentially serious hazard. Hackaday.io user [Nick Sayer] had gotten used to his Hakko soldering iron’s auto shut-off and missed that feature on his de-soldering gun of the same make. So, what was he to do but nip that problem in the bud?

Instead of modding the tool itself, he built an AC plug that will shut itself off after a half hour. Inside a metal project box — grounded, of course — an ATtiny85 …read more

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Cryptanalyse Your Air Con

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Infrared remote controls are simple and ubiquitous. Emulating them with the aid of a microcontroller is a common project that hackers use to control equipment as diverse as televisions, cable boxes, and home stereos. Some air conditioners can be a little more complicated, however, but [Ken]’s here to help.

The root of the problem is that the air conditioner remote was using a non-obvious checksum to verify if commands received were valid. To determine the function generating the checksum, [Ken] decided to bust out the tools of differential cryptanalysis. This involves carefully varying the input to a cryptographic function and …read more

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Snitch On Your AC Devices With Stolen Power

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Low power devices are always intriguing, as they open up possibilities for applications with the need to operate remotely, or for very long periods without attention. There are all manner of techniques for powering such devices, too, such as using solar panels, super capacitors, or other fancy devices. The Micro Power Snitch is one such device, which can report wirelessly on your AC-powered appliances.

The device is built around a tiny ARM microcontroller and an RFM69 radio module. The entire circuit is run by leeching power from an AC current transformer, wrapped around one of the power lines of an …read more

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Skin (Effect) in the Game

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We love to pretend like our components are perfect. Resistors don’t have capacitance or inductance. Wires conduct electricity perfectly. The reality, though, is far from this. It is easy to realize that wire will have some small resistance. For the kind of wire lengths you usually encounter, ignoring it is acceptable. If you start running lots of wire or you are carrying a lot of current, you might need to worry about it. Really long wires also take some time to get a signal from one end to the other, but you have to have a very long wire to …read more

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How Do They Synchronize Power Stations With The Grid?

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There are probably times in every Hackaday reader’s life at which you see something and realise that the technology behind it is something you have always taken for granted but have never considered quite how it works. Where this is being written there was such a moment at the weekend, an acquaintance on an amateur radio field day posted a picture of three portable gas-powered alternators connected together and running in synchronization. In this case the alternators in question were fancy new ones with automatic electronic synchronization built-in, but it left the question: how do they do that? How do …read more

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What Voltage for the All-DC House?

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The war of the currents was fairly decisively won by AC. After all, whether you’ve got 110 V or 230 V coming out of your wall sockets, 50 Hz or 60 Hz, the whole world agrees that the frequency of oscillation should be strictly greater than zero. Technically, AC won out because of three intertwined facts. It was more economical to have a few big power plants rather than hundreds of thousands of tiny ones. This meant that power had to be transmitted over relatively long distances, which calls for higher voltages. And at the time, the AC transformer was …read more

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