Give the Clapper a Hand

While “The Clapper” probably first conjures images of low-budget commercials, it was still a useful way to remotely switch lights and other things around the house. But if the lights you want to switch weren’t plugged into the wall, like a ceiling fan, for example, The Clapper was not going to help you. To add some functionality to this infamous device, [Robin] built one from scratch that has all the extra features built in that you could ever want.

First, the new Clapper attaches to the light switch directly, favoring mechanical action of the switch itself rather than an electromechanical relay which requires wiring. With this setup, it would be easy to install even if you rent an apartment and can’t do things like rewire outlets and it has the advantage of being able to switch any device, even if it doesn’t plug into the wall. There’s also a built-in microphone to listen for claps, but since it’s open-source you could program it to actuate the switch when it hears any sound. It also includes the ability to be wired in to a home automation system as well.

If the reason you’ve stayed out of the home automation game is that you live in a rental and can’t make the necessary modifications to your home, [Robin]’s Clapper might be just the thing you need to finally automate your living space. All the files are available on the project site, including the 3D printing plans and the project code. Once you get started in home automation, though, there’s a lot more you can do with it.

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The Electrical Outlet and How It Got That Way

Right now, if you happen to be in Noth America, chances are pretty good that there’s at least one little face staring at you. Look around and you’ll spy it, probably about 15 inches up from the floor on a nearby wall. It’s the ubiquitous wall outlet, with three holes arranged in a way that can’t help but stimulate the facial recognition firmware of our mammalian brain.

No matter where you go you’ll find those outlets and similar ones, all engineered for specific tasks. But why do they look the way they do? And what’s going on electrically and mechanically behind that familiar plastic face? It’s a topic we’ve touched on before with Jenny List’s take on international mains standards. Now it’s time to take a look inside the common North American wall socket, and how it got that way.

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Why Won’t This Darn Thing Charge?

What is more fun than plugging in your phone and coming back to find your battery on empty? Stepping on a LEGO block with bare feet or arriving hungry at a restaurant after closing probably qualify. [Alex Sidorenko] won’t clean your floors or order you a pizza, but he can help you understand why cheap chargers won’t always power expensive devices. He also shows how to build an adapter to make them work despite themselves.

The cheapest smart device chargers take electricity from your home or car and convert it to five volts of direct current. That voltage sits on the power rails of a USB socket until you plug in a cable. If you’re fortunate, you might get a measly fuse.

Smart device manufacturers don’t make money when you buy an off-brand charger, and they can’t speak to the current protection of them, so they started to add features on their own chargers to protect their components and profit margins. In the case of dedicated chargers, a simple resistor across the data lines tells your phone it is acceptable power. Other devices are more finicky, but [Alex Sidorenko] shows how they work and provides Eagle files to build whatever flavor you want. Just be positive that your power supply is worthy of the reliability these boards promise to the device.

Now you know why connecting a homemade benchtop power supply to a USB cable seems good on paper but doesn’t always get the job done. Always be safe when you make your own power supplies.

Push Big Red Button, Receive Power.

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 is connected to a button, an opto-isolated TRIAC AC power switch, and a ‘pilot’ light indicating power. After a half hour, the ATtiny triggers the opto-isolator and turns off the outlet, so [Sayer] must push the button if he wants to keep working. He notes you can quickly double-tap the button for a simple timer reset.

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Careful Testing Reveals USB Cable Duds

What’s worse than powering up your latest build for the first time only to have absolutely nothing happen? OK, maybe it’s not as bad as releasing the Magic Smoke, but it’s still pretty bewildering to have none of your blinky lights blink like they’re supposed to.

What you do at that point is largely a matter of your troubleshooting style, and when [Scott M. Baker]’s Raspberry Pi jukebox build failed to chooch, he returned to first principles and checked the power cable. That turned out to be the culprit, but instead of giving up there, he did a thorough series of load tests on multiple USB cables to see which ones were suspect, with interesting results.

[Scott] originally used a cable with a USB-A on one end and a 3.5-mm barrel plug on the other with a switch in between, under the assumption that the plug on the Pi end would be more robust, as well as to have a power switch for the jukebox. Testing that cable using an adjustable DC load would prove that the cable was unfit for Pi duty, dropping the voltage to under 2 volts at a measly 500-mA load. Other cables proved much better under load, even those with USB mini jacks and even one with a 5.5-mm barrel. But the larger barrel-plug cable also proved to be a stinker when it was paired with an inline switch. In the video below, [Scott] walks through not only the testing process, but also gives a quick tour of his homebrew DC load.

The lesson is clear: not all USB cables are created equal, so caveat hacker. And if you’ve got a yen to check the cables in your junk bin like [Scott] did, this full-featured smart DC load might be just the thing.

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Finding ESP8266 Inside Big-Box Store IoT Plugs

When we buy new shiny toys, we usually open them up to at least have a look. [Scott Gibson] does the same, apparently. He found an ESP8266 module inside the EcoPlug brand WiFi-controlled wall switches.

The original device was intended to be controlled by a (crappy) app. He sniffed the UDP packets enough to send the on-off signals to an unmodified device, but where’s the fun in that? [Scott] gave it an upgrade by replacing the ESP8266’s firmware with his own and now he’s got a much more capable remote switch, one that speaks MQTT like the rest of his home automation system.

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Hacking a $20 WiFi Smart Plug

The Kankun smart plug is an inexpensive device that lets you switch an outlet on and off over wifi. The smart plug only works with an Android or IOS app that ships with the device, which limits its usefulness to turning things on and off from your phone.

In an attempt to make this device more useful, [LinuxGeek] probed the device with nmap and discovered that it runs OpenWRT. After trying various common default passwords he discovered the login was root/admin. While [LinuxGeek] hasn’t sniffed the protocol yet, others have hacked it a bit further. The plug apparently uses UDP packets to communicate with the Android app, but the packets are unfortunately encrypted.

Rather than hack at the protocol, they wrote code that toggles the GPIO pin from a CGI script and developed a small Windows application that hits the CGI script for simple control from a computer. There’s also a Google+ group where more information and a couple other hacks for these plugs are posted. For $20 (from AliExpress) and with a bit of hacking, this smart plug could be a great way to add wireless control to a home automation system.