I’ve always had a fascination for electronics. I once had a massive 12v setup in my garage that controlled lights, the radio and even the inverter for a TV.

MQTT controlled PC power switch

Today my electronics are a bit smaller. So far I have worked with Sonoff devices and ESP8266 boards.

I use the Sonoff devices to monitor my homelab power draw in real time and remotely turn off the large power draws if they aren’t needed.

The ESP8266 devices take a bit more work. My first dabble into them involved setting up a WiFi connection and MQTT client on the device to connect to Adafruit. From there I could then send an MQTT command to trigger code to close a circuit (effectively turn an led on).

I used this simple design to trigger my computer to turn off. I had a photodiode leftover from my University electronics so I wired it into my PC motherboard. I then just had to enclose the photodiode and the LED next to each other. When the LED turns on the motherboard switch is closed, sending either a power on, power off or hard shutdown command.

MQTT blind motor

Following on from my MQTT adventures I decided to build a circuit based off this design.

I then wired everything together, placed it all in its 3D printed case and tried it out.

I’m not 100% satisfied with it. The 3D printed cog may be off as the chain can slip sometimes so it requires a lot of pressure. But it may just be down to the motor not having enough power as the motor may just not have the torque.