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Open-Source Thermostat For $70

Spark has developed an open-source thermostat that cost just $70 to make, and it did so within a single day. That’s nothing to snub your nose at.


The open source thermostat.
Image Credit:

Before I provide further details about the thermostat, it’s worth noting that the primary reason the project was done so quickly and affordably is that it was an open source project. The team was able to simply integrate an existing open-source technology into their thermostat without any patent-related issues. That technology was the Spark Core, which is a development board that gives it WiFi capability.

Open source technology like this can be improved upon by anyone, so the expertise applied to it isn’t just limited to that of a few engineers on a proprietary technology’s research and development team. It can also be redistributed for free, so that everyone can enjoy it.

The thermostat, which was built from 10:00 AM to 3:00 AM by 3.5 engineers (one went to bed early) using wood and acrylic indicates the fan and heater settings via LEDs, and allows you to control them by turning a ring.

As for the development of the hardware:

“In our case, that means sensors for temperature and humidity, plus a motion sensor to figure out whether you’re home, and relays to control the furnace and the fan. We also need a display so you can see the current temperature, and an enclosure to protect the messy bits.” Then they said, they did some “breadboarding” to create an early prototype.

According to

They chose the Spark Core as the “connected brain,” and showed the temperature on Adafruit LED matrices. The display interface was a I2C bus. The primary sensor was a Honeywell Humidicon temperature and humidity sensor.

The thermostat is also equipped with a Panasonic PIR motion detector.

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Written By

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:


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