home hacks

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Motion Light In Dark Stairwell Brightens Trips To The Basement

March 8, 2015 by 34 Comments

WARNNG: Walking around in the dark could be dangerous to your health! You may bump into something or worse, take a tumble down the stairs. Safety conscious [Ganesh] has come up with a solution for us folks too lazy to manually turn on a light. It’s a simple light controlled by a motion sensor that anyone can put together.

The meat and potatoes of the build is an off-the-shelf motion sensor, the same kind that is used in a home security system. We humans emit infrared energy and that is just what this sensor ‘sees’. The motion sensor is powered by 12 VDC and has a pair of DC output leads that are used to control a relay. [Ganesh] used an standard hobby relay board with built in power spike protection diode and transistor to supply the current required to trip the relay. Closing the relay sends mains power to the AC light bulb. Both the triggering threshold and the ‘on’ time are controlled by potentiometers integrated with the motion sensor.

Check the video out after the break of the device working its magic and lighting the way to [Ganesh’s] basement dungeon…

Continue reading “Motion Light In Dark Stairwell Brightens Trips To The Basement” →

A Secret Door To The Mines Of Moria

March 7, 2015 by 9 Comments

What home movie theater is complete without a secret entrance? [Eclipse_007] had the brilliant idea to make this Lord of The Rings themed hidden door, akin to the entrance way to the Mines of Moria.

It’s a custom door panel filled to the brim with LED lights on the underside. The front panel is a large piece of plexi-glass with a vinyl coating on one side. [Eclipse_007] painstakingly cut the design out of the vinyl coating, all by hand. Once installed the door just looks like another part of the wall. But when touched, the door lights up and then swings open, revealing the movie theater. Plans are already in the works to make it voice controlled to open when the password is spoken.

As one reddit user puts it:

That is probably the coolest thing I have ever seen.

I’m trying to imagine an estate agent introducing your house… two bathrooms, double glazing, five bedrooms, the Westgate of Moria which opens into a basement movie theater when you say Mellon, and a stylish modern kitchen…

Continue reading “A Secret Door To The Mines Of Moria” →

Reverse Engineering Wireless Temperature Probes

March 1, 2015 by 13 Comments

[bhunting] lives right up against the Rockies, and for a while he’s wanted to measure the temperature variations against the inside of his house against the temperature swings outside. The sensible way to do this would be to put a few wireless temperature-logging probes around the house, and log all that data with a computer. A temperature sensor, microcontroller, wireless module, battery, case, and miscellaneous parts meant each node in the sensor grid would cost about $10. The other day, [bhunting] came across the exact same thing in the clearance bin of Walmart – $10 for a wireless temperature sensor, and the only thing he would have to do is reverse engineer the protocol.

These wireless temperature sensors are exactly what you would expect for a cheap piece of Chinese electronics found in the clearance bin at Walmart. There’s a small radio operating at 433MHz, a temperature sensor, and a microcontroller under a blob of epoxy. The microcontroller and transmitter board in the temperature sensor were only attached by a ribbon cable, and each of the lines were labeled. After finding power and ground, [bhunting] took a scope to the wires that provided the data to the radio and took a look at it with a logic analyzer.

After a bit of work, [bhunting] was able to figure out how the temperature sensor sent data back to the base station, and with a bit of surgery to one of these base stations, he had a way to read the temperature data with an Arduino. From there, it’s just a data logging problem that’s easily solved with Excel, and [bhunting] has exactly what he originally wanted, thanks to a find in the Walmart clearance bin.

Control board for a Wi-Fi enabled thermostat

Controlling Central Heating Via Wi-Fi

February 27, 2015 by 11 Comments

If you’ve ever lived in a building with manually controlled central heating, you’ll probably understand [Martin]’s motivation for this hack. These heating systems often have old fashioned valves to control the radiator. No Nest support, no thermostat, just a knob you turn.

To solve this problem, [Martin] built a Wi-Fi enabled thermostat. This impressive build brings together a custom PCB based on the ESP8266 Wi-Fi microcontroller and a mobile-friendly web UI based on the Open Thermostat Scheduler. The project’s web server is fully self-contained on the ESP8266.

To replace that manual value, [Martin] used a thermoelectric actuator from a Swiss company called HERZ. This is driven by a relay, which is controlled by the ESP8266 microcontroller. Based on the schedule and the measured temperature, the actuator lets fluid flow through the radiator and heat the room.

As a bonus, the device supports NTP for getting the time, MQTT for publishing real-time data, and ThingSpeak for logging and graphing historic data. The source code and design files are available under a Creative Commons license.

A protoboard layout for an ATtiny85 door chime

AES-CMAC On An ATtiny85

February 20, 2015 by 35 Comments

[Blancmange] built a custom door chime using an ATtiny85. Unlike most commercial products out there, this one actually tries to be secure, using AES-CMAC for message signing.

The hardware is pretty simple, and a protoboard layout is shown in the image above. It uses the ATtiny85 for control, with an LM380N audio amplifier, and a low cost 315 MHz receiver.

The more impressive part of the build is the firmware. Using AVR assembly, [Blancmange] managed to fit everything into the 8 Kbytes of flash on the ATtiny85. This includes an implementation of AES-CMAC, an AES cypher based message authentication code. The transmitting device signs the request with a key shared between both devices, and the receiver verifies that the message is from a trusted transmitter.

Fortunately, the assembly code is very well commented. If you’ve ever wanted to take a look into some complex ASM assembly, this is a great project to check out. The source code has been released into the public domain, so the rest of us can implement crypto on this cheap microcontroller with much less effort.

Automatic Garage Door Opener Works For Your Cat

February 17, 2015 by 14 Comments

Using an Arduino or Raspberry Pi to perform a task in the real world is certainly a project we’ve seen here before, and certainly most of these projects help to make up the nebulous “Internet of Things” that’s all the rage these days. Once in a while though, a project comes along that really catches our eye, as is the case with [Jamie’s] meticulously documented automatic garage door opener.

This garage door opener uses an ATMega328 to connect the internet to the garage door. A reed switch is installed which lets the device sense the position of the door, which is relayed back to the internet. [Jamie] wrote an Android app that can open and close the door and give the user the information on the door’s status. One really interesting feature is the ability to “crack” the garage door. This is done by triggering the garage door opener twice with a delay in between. From the video after the break we’d say this is how [Jamie’s] cat gets in and out.

We love seeing projects that are extremely well documented so that anyone who wants to make one can easily figure out how. Internet-connected garage door openers have been featured in other unique ways before too, but we’ve also seen ways to automatically open blinds or chicken coops!

RasPi Garage Door

A Raspberry Pi Garage Door Opener

February 15, 2015 by 32 Comments

We can never seem to get enough garage door hacks around here. [Tanner’s] project is the most recent entry into this category. He’s managed to hook up a Raspberry Pi to his garage door opener. This greatly extends his range to… well anywhere with an Internet connection.

His hack is relatively simple. He started with the garage door opener remote. He removed the momentary switch that was normally used to active the door. He bridged the electrical connection to create a circuit that was always closed. This meant that as long as the remote had power, the switch would be activated. Now all [Tanner] had to do was remove the battery and hook up the power connectors to his Raspberry Pi. Since the remote works on 3.3V and draws little current, he is able to power the remote directly from the Pi. The Pi just has to turn its pin high momentarily to activate the remote.

The ability to toggle the state of your garage door from anywhere in the world also comes with paranoia. [Tanner] wanted to be able to tell if the door is up, down, or stopped somewhere in the middle while he was away from home. He also wanted to use as little equipment as possible. Since he already had an IP camera in the garage, he decided to use computer vision to do the detection.

He printed off two large, black shapes onto ordinary white computer paper. One was taped to the top of the door and one to the bottom. A custom script runs on the Pi that grabs the latest image from the camera and uses OpenCV to detect the shapes. If both shapes are visible, then the script can assume the door is closed. Otherwise, it’s likely open. This makes it easier for [Tanner] to know if the door is opened or closed without having to check the camera himself.

Can’t get enough garage door hacks? Try these on for size. Continue reading “A Raspberry Pi Garage Door Opener” →