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When you don't know how much power your air conditioner draws, it's easy to leave it running without feeling too guilty. And then the electricity bill comes...

An IoT RGBW LED controlled via MQTT with integrated motion and illuminance sensor.

Air conditioners consume a fair amount of electricity. As such, forgetting to turn one off before leaving one's home can result in an expensive electricity bill. This is a Wi-Fi enabled controller for air condtioners, which can turn the unit on or off according to MQTT messages. It is built around an Wemos D1 mini and interfaces with the AC using an IR LED.

I got my hands on a 600W 12V inverter so I decided to experiment with generating my own electricity.

This is an IoT ceiling light controller which includes an HC-SR501 PIR motion sensor. It is built around a Wemos D1 mini (ESP8266 breakout board), which controls a homemade TRIAC breakout board. TRIACs provide the advantage of switching devices on and off silently, as opposed to a mechanical relay.

Smartwatches can be rather expensive and tend to be known for their poor battery life. On the other hand, Xiaomi's Mi band 2 is cheap and its battery lasts for up to 20 days. However, the Mi band 2 is mainly limited to fitness tracking functions, at least without the appropriate apps.

Few would argue that having lights turned on in a room without occupant is a waste of electricity. Ideally, lights and other appliances like air conditioners would only be turned on when someone is around. This project is a NodeJS application that gathers data about the occupancy of an apartment and manages appliances accordingly.

I've been using&nbsp;<a href="https://www.home-assistant.io/" rel="noopener noreferrer nofollow">Home Assistant</a>&nbsp;to control my home IoT devices for a while. Although it fulfills all my needs, I wanted to make my own system so as to get a fully customized smart home control panel and learn how to build such an application in the process.