Repurposing Components from a Broken Air Purifier | May 03 2026, 15:00

The air purifier broke down, so I bought a used one with a new cartridge for the price of a replacement cartridge plus $40. I completely disassembled the old one, extracted the reusable components, and figured out how it works. Just like in school 🙂

Inside, it comprises:

– an ESP32-WROOM-32D controller. But a part of the board responsible for voltage burned out, so it’s trash now.

– a CO sensor MQ-7 (unfortunately soldered to the board, but can be desoldered). Though, it needs a heating cycle for correct operation. First 5V (60 sec) for sensor cleaning, then 1.5V (90 sec) for measurement. But, it can also be used elsewhere.

– Plantower PMS9103M — a high-precision laser sensor for measuring airborne particulate matter concentrations (PM1.0, PM2.5, PM10). Can be connected to Arduino, specification available.

– a microwave motion sensor (radar), model RCWL-0516. Can be connected to Arduino, very simple interface. Detects motion up to 5-7 meters around within 360 degrees.

– 200W Snowfan YY225H310B motor. Also quite simple to connect, but it requires 310V DC plus 15V for speed control. But that’s all.

– a Hall sensor (magnet)

The motor is the most valuable part. It’s priced at $100 on eBay. Though, it should probably be tested first to see if it hasn’t burned out.

Silence for Cents: Exploring the SwissBrand 120-Pack Mouth Tape | April 24 2026, 18:25

If your other half needs to be silenced temporarily, you can buy a kit for 120 silencings from us, averaging just under six cents per silence

Yuki’s Mysterious Bi-Annual Behavior Shifts | April 09 2026, 14:31

Yuki’s “ooooh” mode is activated again (April 7, 2026). It usually lasts a few days in April and October.

Previous occurrences were –

– October 15-20, 2025

– April 11, 2025

– April 1-4, 2024

– February 2, 2023,

– October 27, 2022,

– March 15, 2022

Behavior changes during this period include:

1) He might sing songs for hours on end. For instance, at six in the morning.

2) Suddenly, he likes to go for walks. Usually, he does not. Even though he always has access to the yard, he specifically needs to go on a walk. He might go to the door and knock on it with his paw. Usually, at the word “walk,” he rushes to the third floor.

Now, he looks into your mouth when you’re talking to him. Always seems to be waiting for something, possibly expecting the question of whether he wants to go for a walk. He knocks on the window and the front door with his paw.

And yes, he starts wanting to walk at around six in the morning, and then again soon after returning from a walk.

3) On the walk, he sticks his nose in the grass every five minutes, and it’s hard to pull him away. Usually, this is rare, but now it’s constant.

4) He might sit and watch the sunset for half an hour.

5) Unstable appetite, occasionally. You put meat on top of his food, and he doesn’t even look at it.

Nadezhda’s Firsts: Oil Painting and Piano | March 12 2026, 18:55

Last week, Nadezhda Shulga painted an oil painting for the first time in her life and played the piano with one hand for the first time in her life! Nadya, well done!!! She asked me so many times to paint nature, that she eventually went ahead and painted it herself.

Harnessing Productivity: Personal Techniques That May Just Work for You | February 17 2026, 22:21

I formulated for myself how I manage to get a lot done (actually, I don’t). It’s not a fact that it will work for others. But still, here are the points:

1. Do what you like. You need to do what your heart is in at the moment. If you force yourself, efficiency drops tenfold.

2. Sports anger as a catalyst. You need to treat failure not as a tragedy, but as a personal insult from the task. Anger is the quickest way to enter a state of hyper-focus, turning “didn’t work out” into “oh really, now watch me”.

3. Seamless switching. As soon as energy in one task has waned or the task is done — leap to the next funnel that beckons right now. It might not always be work-related. For instance, I might play the piano, draw, program, write a book, or do work.

4. Completing. Take a chunk that you can chew and bring it to a plus-minus norm. Don’t drop it midway, while there’s still momentum. Finish and refine – that’s a task for the next “high”.

5. If you can’t break through a wall — don’t smash your head against it. Mark the point of stopping, say “I’ll remember you” and retreat to return with a different tool or a different mood. The main thing is to keep this “open gestalt” in active memory and not tuck it away for too long.

6. An external promise is sacred. If you promised a deadline by Monday, personal comfort (like sleep on Saturday) is sacrificed. This pain teaches you to filter promises in the future. Your word must have physical weight.

7. The plus one principle. Always do a bit more than expected of you. How much more is a question of context, resources, desire, but the delta should be tangible.

8. The principle of useful output. Any product of activity should be in a form that can be delivered. The English word for this is ‘deliverable’. Simply getting to grips with something is not a product. But understanding it and documenting it in Confluence is a product. A letter, an article, code – anything.

9. “You gotta, Fedya, you gotta.” Perform mandatory ceremonies and necessary bureaucracy as an inevitable evil that simply has to be done anyway. Need to pass some stupid training every six months? Allocate an hour for it and suffer through.

10. Have the best tools for the task. If you don’t have them, strive to possess them and learn to use them.

Three more principles, which seem unteachable but are very helpful:

0. Don’t get irritated and don’t irritate others.

1. The ability to instantly separate the important from the junk, and the urgent from the hustle. This is an intuition that only develops with years “in the field”. And total curiosity – the ability to find excitement in any topic. This applies to everything – including who to talk to and when to go to the store.

2. If you’re bored — it means you just haven’t dug deep enough. Interest is a matter of immersion scale and having the right people, books, YouTube videos, etc. Eventually, there simply are no topics that seem boring.

3. Lifetime learning principle. Any project is a legal excuse to become smarter at someone else’s expense. Look for what ignites you in routine and what you’ve long wanted to learn. See a task that would be more elegantly solved with a script in Haskell, a language you’ve never seen before? Then today, we are learning Haskell. True, enthusiasm should not bury the deadline. You need to deliver results, even if the experiment completely fails. Promise foundation first, then decorate with the new skill.

These principles have a downside. For instance, I progress very slowly in playing the piano because good progress requires two other principles that don’t “get along” with my principles above:

1. The “one more lap” principle. If you sat down, and got tired after an hour, you need to spend two more, and then you can get up.

2. The “clenched teeth – go” principle. If you’ve taken on learning something, do it regularly, preferably at the same time, and if necessary, through “I don’t want to”.