Yes, there have been loads of people doing similar things! ESPHome already has a tutorial covering exactly this!

I’m writing this up because the approach that I ended up taking was not the intended/planned approach.

The Geiger Counter

I originally pulled the trigger on this particular version because it had a built in screen attached to a micro controller.

I naïvely thought that I’d be able to get a simple UART from the 4 pins next to the microcontroller or maybe even get data directly off of the micro USB port.

Millimeter Wave technology has recently hit “mass consumer product adoption” price points. A casual search for “human presence sensor” on Ali Express will turn up a seemingly endless number of sub $40 devices that can detect movement far more accurately than any old PIR sensor.

Each listing is fairly generic; there’s no explicit manufacturer details but they all use the same marketing images:

As the photos below will show, neither device is super well marked with a model number so I’ll just refer to each by either the color of the enclosure or by the radar sensor inside.

PC (power) remote control

While doing research for a potential project, I stumbled onto a device that fit’s so squarely into that “it’s so simple and obvious, why didn’t I think tof that?!” category that I immediately placed an order for a few.

That device?

A simple WiFi equipped micro controller that gets wired between the power button on a PC and the motherboard. This makes it possible to remotely control and monitor the power state of any PC!

For the longest time, I had a dedicated raspberry pi with a GPS module acting as the ntp server for my home network. I chose to use a dedicated host for this because my router - at the time - did not have a serial port that I could leverage.

Background

Long story made very short: the amplifier inside my ancient 2.1 desktop speakers died and I couldn’t find anything “off the shelf” that would serve as a suitable replacement and integrate well with Home Assistant.

So if you can’t buy it, you have to build it! And as it turns out, there’s a whole community of audiophiles that have published designs on all the usual places you’d find free designs for makers. Similarly, there’s a few companies that seems to specialize in audio electronics aimed specifically at people that are building their own speaker systems and just want someone else to handle the electronics and software.