Solenoids And Servos For Self Actuated Switches

January 18, 2018 by Brian Benchoff 56 Comments

The new hotness in home automation is WiFi controlled light switches. Sure, we’ve had computer-controlled home lighting for literally forty years with X10 modules, but now we have VC money pouring into hardware, and someone needs to make a buck. A few years ago, [Alex] installed WiFi switches in a few devices in his house and discovered the one downside to the Internet of Light Switches — his light switches didn’t have a satisfying manual override. Instead of cursing the darkness for want of an Internet-connected candle, [Alex] did the only sensible thing. He installed electromagnets, solenoids, and servos behind the light switches in his house.

The exact problem [Alex] is trying to solve here is stateful wall switches. With an Internet-connected lamp socket, the wall switch no longer functions. Being able to turn on a light when your phone is out of charge is something we all take for granted, and the solution is, of course, to have Internet-connected switches.

Being able to read the state of a switch and send some data off to a server is easy. For this, [Alex] used a WeMos D1 mini, a simple ESP8266-based board. The trick here, though, is stateful switches that can toggle themselves on and off. This is a mechanical build, and although self-actuated switches that can flip up and down by computer command exist, they’re horrifically expensive. Instead, [Alex] went the DIY route, first installing electromagnets behind the switches, then moving to solenoids, and finally designing a solution around four cheap hobby servos. The entire confabulation stuffed into a 2-wide electrical box consists of two switches, four hobby servos, the D1 mini, and an Adafruit servo driver board.

The software stack for this entire setup includes a NodeJS server connected to Orvibo Smart Sockets over UDP. Also on this server is a WebSocket server for browser-based clients that want to turn the lights on and off, a FauXMo server to turn the lights on and off via an Amazon Echo via WeMo emulation, and an HTTP server for other clients like [Alex]’ Pebble Watch.

This is, without question, the most baroque method of turning a lamp on and off that we’ve ever seen. Despite this astonishing complexity, [Alex] has something that is also intuitive to use and, to borrow an applhorism, ‘Just Works’. With a setup like this, anyone can flick a switch and turn a lamp on or off over the Internet, or vice-versa. This is the best Home Automation build we’ve ever seen.

You can check out [Alex]’ video demo of his build below, or his GitHub for the entire project here.

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An Introduction To Solid State Relays

September 26, 2017 by Sean Boyce 54 Comments

When we think of relays, we tend to think of those big mechanical things that make a satisfying ‘click’ when activated. As nice as they are for relay-based computers, there are times when you don’t want to deal with noise or the unreliability of moving parts. This is where solid-state relays (SSRs) are worth considering. They switch faster, silently, without bouncing or arcing, last longer, and don’t contain a big inductor.

An SSR consists of two or three standard components packed into a module (you can even build one yourself). The first component is an optocoupler which isolates your control circuit from the mains power that you are controlling. Second, a triac, silicon controlled rectifier, or MOSFET that switches the mains power using the output from the optocoupler. Finally, there is usually (but not always) a ‘zero-crossing detection circuit’. This causes the relay to wait until the current it is controlling reaches zero before shutting off. Most SSRs will similarly wait until the mains voltage crosses zero volts before switching on.

If a mechanical relay turns on or off near the peak voltage when supplying AC, there is a sudden drop or rise in current. If you have an inductive load such as an electric motor, this can cause a large transient voltage spike when you turn off the relay, as the magnetic field surrounding the inductive load collapses. Switching a relay during a peak in the mains voltage also causes an electric arc between the relay terminals, wearing them down and contributing to the mechanical failure of the relay.

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Joe Activation With A WiFi-Controlled Electrical Outlet

September 9, 2017 by John Baichtal 13 Comments

[Mike] is the only one in his house who drinks coffee, and uses a simple single-serving brewer with no auto-on feature. And since no one really wants to have to stand around making coffee in the morning, [Mike]’s solution was to IoT-ize his electrical socket.

MQTT Dash is an Android app “for nerds only ;)”

The project consists of a relay board controlled by an ESP8266-packing Adafruit Huzzah. It’s all powered by a 9V power supply with a regulator supplying the relay coil and Huzzah with 5V. [Mike]’s using CloudMQTT to communicate with the outlet.

We often see these automation projects hit a wall when it comes to adding a user-side dashboard. [Mike] is using a free Android app called MQTT Dash which allows for a number of different UI components and even had coffee maker icons already built in. It’s certainly worth a look for your own projects. [Mike] uses it to turn on the outlet for 10 minutes, and by the time he grabs half-and-half the outlet is already off again.

It turns out that connecting coffee pots to the Internet is a driving force among out readers. This one alerts the whole office when the coffee is done, while another one is controlled by Alexa. Then again, sometimes all you can do is reverse engineer the Internet of coffee.

Me Casa Es Techno Casa

September 7, 2017 by Inderpreet Singh 13 Comments

“Jarvis, make me a sandwich” is not a reality yet. Though there exist a lot of home automation products out there today, commercial solutions just don’t make the cut for the self-respecting geek. So [Matias] took the DIY route with his La CasaC Home Automation project and achieved the functionality he was after.

[Matias’] project is one of the most elaborate and large-scale DIY home automation projects we have seen in recent years. With over 200 nodes, this project took a number of years of planning and execution. The core of the design is the ever popular Raspberry Pi running OpenHAB to ease the pain of customization and integration with various protocols. To further simplify the ginormous task, the design uses RS485 to communicate between master and slave devices.

Each wall node is managed by a nearby Arduino which in turn talks to a central Arduino Mega. OpenHab takes care of the higher functions such as UI, integration with existing hardware such as the solar heater, media center control, and RFID and keypad control. Sensor data aggregation and building management is done centrally with data funneled to a separate NAS system as long-term storage.

What makes this project awesome is that [Matias] did not integrate a Raspberry Pi into his house, no! He actually integrated his entire house around the system because this build includes the construction of the house as well. Take a look at this Google Photos Gallery to see the photographic progress of the build. That is amazing!

The code and snippets are available on GitHub for your viewing pleasure though that seems the easy part. If this inspired you, then also take a look at the Raspberry Pi Home Automation of a Gingerbread House if you’d like to try it out before fully committing.

Have Alexa Open Your Garage Door

September 3, 2017 by John Baichtal 17 Comments

[yoyotechKnows] built an Alexa-controlled garage door opener after his Liftmaster stopped working. Now all he has to do is holler at his mobile phone and he can raise and lower his garage doors at will.

His project is based around a Photon WiFi kit, with a pair of LCC 120 digital relays triggering the two doors, reed switches, and a serial-equipped LCD to display door status, with Alexa, IFTTT, and OpenHab to process the commands. You can find his code in the project writeup.

Currently he has a LCD display informing him of the status of each door, hot glued a reed switch to keep track of whether each one is closed. This might seem a little bit extraneous since he can also just look at the doors from within the garage. However, he’s thinking about putting the display inside his house. But couldn’t he just ask Alexa?

We love us our home automation here at Hackaday, with everything from swimming pools to chicken coops rigged for app control and datalogging.

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Turning On Your Amplifier With A Raspberry Pi

August 27, 2017 by Jenny List 17 Comments

Life is good if you are a couch potato music enthusiast. Bluetooth audio allows the playing of all your music from your smartphone, and apps to control your hi-fi give you complete control over your listening experience.

Not quite so for [Daniel Landau] though. His Cambridge Audio amplifier isn’t quite the latest generation, and he didn’t possess a handy way to turn it on and off without resorting to its infrared remote control. It has a proprietary interface of some kind, but nothing wireless to which he could talk from his mobile device.

His solution is fairly straightforward, which in itself says something about the technology available to us in the hardware world these days. He took a Raspberry Pi with the Home Assistant home automation package and the LIRC infrared subsystem installed, and had it drive an infrared LED within range of the amplifier’s receiver. Coupled with the Home Assistant app, he was then able to turn the amplifier on and off as desired. It’s a fairly simple use of the software in question, but this is the type of project upon which so much more can later be built.

Not so many years ago this comparatively easy project would have required a significant amount more hardware and effort. A few weeks ago [John Baichtal] took a look at the evolution of home automation technology, through the lens of the language surrounding the term itself.

Via Hacker News.

Home Automation: Evolution Of A Term

July 26, 2017 by John Baichtal 31 Comments

Home automation: for me the term recalls rich dudes in the ’80s who could turn off their garage lights with remote-control pads. The stereotype for that era was the more buttons your system had—even non-enabled ones—the more awesome it was, and by extension any luxury remote control had to be three times the size of any TV remote.

And it was a luxury–the hardware was expensive and most people couldn’t justify it. Kind of like the laser-disc player of home improvements. The technology was opaque to casual tinkering, it cost a lot to buy, and also was expensive to install.

The richie-rich stereotypes were reinforced with the technology seen in Bond movies and similar near-future flicks. Everything, even silly things, is motorized, with chrome and concrete everywhere. You, the hero, control everything in the house in the comfort of your acrylic half-dome chair. Kick the motorized blinds, dim the track lighting, and volume up the hi-fi!

This Moonraker-esque notion of home automation turned out to be something of a red herring, because home automation stopped being pretty forever ago; eventually it became available to everyone with a WiFi router in the form of Amazon Echo and Google Nest.

But the precise definition of the term home automation remains elusive. I mean, the essence of it. Let’s break it down.

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