Move Over, Google Nest: Open Source Thermostat Is Heating Up the Internet of Things

In the wake of Google’s purchase of connected devices interest Nest, the gents at [Spark] set about to making one in roughly a day and for a fraction of the cost it took Nest to build their initial offering. [Spark]’s aim is to put connected devices within reach of the average consumer, and The Next Big Thing within the reach of the average entrepreneur.

The brain is, of course, [Spark]’s own Spark Core wi-fi dev board. The display is made of three adafruit 8×8 LED matrices driven over I²C. Also on the bus is a combination temperature and humidity sensor, the Honeywell HumidIcon. They added some status LEDs for the furnace and the fan, and a Panasonic PIR motion detector to judge whether you are home. The attractive enclosure is made of two CNC-milled wood rings. The face plate, mounting plate, and connection from the twistable wood ring to the potentiometer is laser-cut acrylic.

[Spark]’s intent is for this, like the Nest, to be a learning thermostat for the purpose of increasing energy efficiency over time, so they’ve built a web interface with a very simple UI. The interface also displays historical data, which is always nice. This project is entirely open source and totally awesome.

If you have an old Android phone lying around, you could make this open source Android thermostat.

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Wireless Thermostat

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The thermostat in [Tom’s] 100-year-old house is two floors up from where the furnace is located, so a broken wire in the wall was just the catalyst needed to design a wireless thermostat.

The system is based on a customized PCB [Tom] designed called the Magic Mote. The board contains an MSP430 microcontroller, a low power NRF24l01+ wireless transceiver, and various sensor interfaces. The wireless thermostat project uses two of these boards; one monitors the temperature on the second floor and the other controls the furnace in the basement.

The temperature sensing is done using a DHT22/AM2303 temperature and humidity sensor, which is a convenient choice, since the part is calibrated and handles the analog digital conversion; you just need one digital pin to retrieve the temp/humidity data. To control the furnace, [Tom] used the local 24VAC and a latching relay to drive the heater signal. The 24VAC also powers the board, so a door-bell transformer steps the voltage down to something more usable; about 11VAC or so, which is then rectified, filtered, and regulated down to what the control electronics like to see (3.3V/5V).

This project is actually still in the early stages of what [Tom] has planned; a network of sensors and appliances with a beagle bone base station. We can’t wait to see what’s next for this project; maybe we’ll even see some voice control, like in this epic Siri controlled home automation project.

[via Dangerous Prototypes]

DIY Pellet Fed Boiler is Hot Stuff

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[Firewalker] has designed a great pellet burning boiler (translated). Wood and biomass pellets have gained popularity over the last few years. While freestanding stoves are the most popular method of burning the pellets, [Firewalker] went a different route. He’s converted a boiler from what we assume was oil to pellet power. An Arduino controls the show, but don’t hold it against him. [Firewalker] is just using the Arduino as an AVR carrier board.The software is all written in C using AVR studio. The controller’s user interface is pretty simple. A two-line character based LCD provides status information, while input is via buttons. Once the system is all set up, thermostats are the final human/machine interface.

Burning pellets requires a bit of prep. A cleanup of the burn chamber must be performed before each burn. The AVR is programmed to handle this. Once the chamber is clean, new pellets are fed in via an auger system. The burner is monitored with a standard flame sensor. When the fire is up the pellets feed in until the boiler gets up to temp. Then the system enters a standby mode where it feeds in just enough pellets to maintain the flame. When the thermostats stop calling for heat, the whole system shuts down, ready for the next burn.

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Rolling your own furnace controller

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[Viktor’s] found an opportunity to put his embedded design skills to use when the furnace controller in his building went out. He admits it would have been much easier to just purchase a replacement, but not nearly as fun. Instead he built this furnace controller based on a PIC 18F4550.

First off, you may find it strange that we’re calling this a furnace controller and not a thermostat. But a study of the hardware schematic reveals that the device doesn’t have the ability to sense temperature. It merely switches the furnace on and off based on a time schedule. We guess this is for an apartment building where measuring the temperature at one central point doesn’t suffice?

At any rate, the build is clean and the UI looks quite easy to use. Inside there’s a board-mounted 12V relay which controls the furnace. The schedule is saved to the EEPROM of the microcontroller and time is kept by a battery-backed DS1307.

We’d love to see this extended in the future. Some possibilities would be adding internet connectivity and implementing a mesh network of temperature sensors which would give feedback to the main unit.

Open source Android thermostat

Put that old Android phone to good use by mounting it on the wall as a smart thermostat. This open source hardware and software project lets you replace your home’s thermostat with an Android device which adds Internet connectivity and all that comes with the increase in computing power.

The brunt of the hardware work is taken care of by using an IOIO board which makes it easy to interface any Android device with the simple hardware which switches your HVAC equipment. We’ve been waiting for the launch of the new IOIO design and if it comes in at a lower price as has been rumored that makes this project in the price range of the least expensive of programmable thermostats (assuming you already have an Android device to devote to it). Simply etch your own board to host the relays and voltage rectifier and you’re in business.

There is a client and server app, both free in the Play Store. The server runs on the wall-mounted device with the client offering control via a network connection. The features of the system are shown off quite well in the video after the break.

This sounds like a perfect use for that phone you ripped out of the pages of a magazine.

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Getting a Nest thermostat to work in Europe

[Julian] was really excited to get his hands on a Nest learning thermostat. It’s round, modern design will make it a showpiece in his home, but he knew there would be a few hiccups when trying to take advantage of its online features. That’s because [Julian] lives in Spain, and Nest is only configured to work in North America. But as you can see above, he did a bit of hacking to get it displaying his actual location.

The Nest is web-connected and phones home to the company’s server to handle configuration. Since they’ve made the decision to only support a portion of the world [Julian] had to do a little bit of digging to bend it to his will. He used Wireshark to sniff the packets it was sending. The calls to the company’s server use SSL, but the device also contacts the Weather Underground for data and this is not encrypted. So he was able to intercept that with his router and inject custom information. It’s not a full solution, but he’s part way there.

We’d really like to see what is possible with this device so please send us a link to any Nest hacks of your own.

Quieting an inexpensive bench power supply

[Mike] just purchased this Atten APS3005S bench power supply for around $80. It does the job, but boy is it noisy! We were pretty surprised to hear it fire up in the video after the break. To make matters worse, the noise is persistent since the fan never shuts off. Having worked with other bench supplies he knew that a common feature included in many models is temperature controlled case fans. He set out to quiet the fan and implement a temperature switch.

For this project [Mike] had the benefit of looking at a nearly identical model that does have temperature switching. He discovered that the board on this one has a through-hole zero ohm resistor populated in place of a thermostat switch. That switch closes the connection at or above 45 degree Celsius, thereby turning on the cooling fan. Bridging the traces with a zero ohm resistor to save on production costs is what caused the fan to run continuously. After replacing the resistor with a KSD-01F and swapping out the stock fan for a high-quality version [Mike] has takes a noise maker and turned it into a device that’s kind to the ears.

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