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Monitoring my home's air quality (CO2, PM2.5, Temp/Humidity) with AirGradient's DIY sensor

A few months ago, I found this Hacker News post about the AirGradient DIY Air Quality Monitor. I had already been considering buying an AirThings Wave Plus sensor to monitor my home's CO2 levels, but the high price and limited 'ownership' of the data coming from it turned me off.

AirGradient DIY Air Quality Sensor - Focus Stacked by Jeff Geerling

So I built two AirGradient DIY air quality monitor boards (see above), and integrated them into my Prometheus + Grafana home monitoring setup I've been using to monitor other things in my house:

AirGradient DIY Grafana Dashboard for CO2 PM2.5 Temperature Humidity monitoring

Review: Sennheiser MKE 200 supercardioid on-camera mic

Sennheiser MKE 200 mini shotgun microphone

The Sennheiser MKE 200 is a compact shotgun microphone, and it's a small and cheap way to improve the sound you get for vlogging, or b-roll footage over the built in mic on your camera or phone.

I bought this microphone for use making my YouTube videos, and I'm not getting any compensation for this review. I just wanted to see if it would be a good 'run and gun' mic for some of my work, and to share my thoughts here.

After using it for a few weeks, I'm happy with the mic, but it didn't blow me away.

There are three things to consider with the MKE 200: size, price, and performance.

I hope you're most interested because of the size and price. I hate to be the bearer of bad news, but if you're main interest is performance, you'll need to increase your budget and the size of your equipment carrying case—and maybe hire a boom operator!

Microphones and physics

Why is that?

Time Card and PTP on a Raspberry Pi Compute Module 4

Ahmad Byagowi, the project lead for Open Compute Project's Time Appliance, reached out to me a couple weeks ago and asked if I'd be willing to test the new Time Card Facebook had announced in mid-August on a Raspberry Pi Compute Module 4. Since I have a sort of obsession with plugging anything and everything into a Pi to see what works and what doesn't, I took him up on the offer.

The official specs had PCI Express Gen 3 on a x4 slot as a requirement, but it seems the Gen 3 designation is a little loose—the card and its driver should work fine on an older Gen 2 bus—like the one the Raspberry Pi Compute Module 4 exposes if you use the official IO Board:

Raspberry Pi Compute Module 4 IO Board PCI Express Slot

The slot is x1, but you can plug in any width card using an adapter like this one or by hacking an open end into it with a razor saw or dremel tool.

Modeling my Grandpa with 3D Photogrammetry

Today I released a video about how—and why—I 3D Printed my Grandpa and put him on my bottle of ketchup. Watch it here.

I sculpted a bust of my Grandpa in high school, gave it to my grandparents, got it back after he died and my Grandma moved out of her house (I wrote a tribute to my 'Grandpa Charlie'), and I kept on moving it around my office because I didn't have room for it:

Grandpa bust - terracotta by Jeff Geerling in 2001 - original statue
Grandpa by Jeff Geerling, terracotta, 2001.

I decided it had to go, but asked my extended family if anyone wanted the statue (thinking it would be sad to destroy it). One enterprising cousin suggested he could 'copy' the statue in smaller form using photogrammetry:

I made a custom ceiling mount for my camera

I shoot the 'A-roll' for my YouTube videos with a Sony a6000 and a small Glide Gear TMP 75 smartphone teleprompter:

Tripod setup with teleprompter and Sony a6000

Until recently, I had these mounted on a tripod just off the back corner of my desk:

Tripod in the way

Some people mount semi-permanent camera rigs on a pole on their desks (example), but my adjustable-height desk (by UPLIFT) is not rock solid, so sometimes when I'm typing or accidentally bump the desk, anything mounted to the desktop wobbles.

For lights, monitors, etc., a little wobble isn't a problem. But even with image stabilization in my camera, the wobble becomes noticeable if I have the camera physically attached to my desk.

Why build a Raspberry Pi Cluster?

Raspberry Pi Cluster next to a banana for scale

After I posted my Raspberry Pi Blade server video last week, lots of commenters asked what you'd do with a Pi cluster. Many asked out of curiosity, while others seemed to shudder at the very idea of a Pi cluster, because obviously a cheap PC would perform better... right?

Before we go any further, I'd say probably 90 percent of my readers shouldn't build a Pi cluster.

But some of you should. Why?

Well, the first thing I have to clear up is what a Pi cluster isn't.

Note: This blog post corresponds to my YouTube video of the same name: Why would you build a Raspberry Pi Cluster?. Go watch the video on YouTube if you'd rather watch the video instead of reading this post!