Quiet Airtags

I didn’t post several years ago about the GPSes I installed on our farm vehicles. It felt like painting a target on my back. It took quite a bit of figuring out to set up Particle.io‘s early asset trackers. They’ve since created a dedicated preprogrammed and well polished device, seeing an opportunity in the success of the early hobbyist version I suppose. I never posted my setup, code, or experience but let’s just say it worked well for a few years, for very cheap. Unfortunately, the 2G network they relied on was eventually retired, and that forced me reconsider options.

And well, an obvious contender these days are Airtags. I bought a few for testing, and they quickly became the obvious choice. I replaced bulky cellular GPSes with them and folded them into home monitoring. Watching for geofences, battery status, and last contact.

While I can’t wire them directly to the vehicle’s battery, their battery does seem to last a good year (Vermont winters wear them down faster). And they come with several huge advantages over GPSes.

  • A mesh network of people’s iPhones has a lot better coverage than cellular in a rural area. Cell phones will report them when they finally get to a tower or some wifi.
  • They aren’t subject to tree or cloud cover.
  • They are tiny! I went through great lengths to paint and find a place for bulky GPS boxes. Airtags on the other hand will live anywhere.
  • They are cheap, and have no recurring cost (except the cell battery once a year).

These advantages led me to significantly lower the bar to what I stick them on. It’s no longer reserved for the expensive vehicles. If it costs money and isn’t fastened to the ground, it gets an Airtag.

Of course when used as theft tracking, their chirping is problematic. And so I finally bit the bullet and gave them the surgery they need to make them quiet. And it was very very trivial, I should have done this much earlier.

Open them up, I used a stronger blade than the exacto for prying. Note the 3 sharpie dots to point tabs.

I simply snipped the 2 wires going to the speaker

Still works!

Beefed up Sensoring

A friend bought a couple of Sensirion SEN54s and I helped him get one working, and ended up buying the extra from him. It had been a few years since I researched what sensors were out there that worked well with Raspberry Pis, and were more on the industrial side than the hobbyist side. I was immediately enthused by Sensirion’s documentation, and their sensor looked top notch. My friend did all the homework on reading specs and comparing with others, it was really a no brainer.

With this SEN54 we’ve gained:

  • accurate humidity (the previous sensor was worthless)
  • VOC
  • PM1.0
  • PM2.5
  • PM4.0
  • PM10.0

It’ll be interesting to see the patterns. I’m honestly a little worried about what the particles will reveal seeing as we’re running 2 wood stoves in the house for half of the year. Reassuringly, the first few readings show we’re in the green, but then Nicole opened the stove to let out a bunch of grilled cheese sandwiches and the readings skyrocketed well above WHO guidelines for particles.

But those are only delicious cheese particles finding their way into your nostrils, surely that can’t have and adverse health effect. Jokes aside it’s interesting to see how much of a tail this benign event has. I’ll be really curious to discover more, I really have no idea what I’m looking at yet.

I am very glad to see the Pis become established as industry capable devices. It’s honestly remarkable what I’ve thrown at them over the years while they kept serving their purpose.

Crutch Guitar

That’s right, crutch guitar. I got swept into the world of cigar box guitars trying to make Robin’s broken leg somewhat fun.

Downloads

crutch_guitar.stl

crutch_guitar.skp

Pics

The bridge

On the back I added some metal nuts to act as washers so the string ends wouldn’t eat into the plastic.

The head could be adjusted a little but it’s good enough to play with the concept.

It sounds and works a lot better than I thought it would. And Robin’s way into it. Although I underestimated how hard it would be to play it without frets. It’s very much a different cat, people online make it look easy :).