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Pi Lab
Raspberry Pi, microcontrollers, sensors and things that blink
Raspberry Pi builds, ESP32 and Arduino projects, home automation, GPIO pain, SD cards that die at the worst moment, and the cluster of four Pis you swear is for "learning Kubernetes". Post your builds with photos.
17 members
15 posts
Created May 2026
+1
Community rules
Show the build
Photos, parts list, wiring. "Mine does not boot" with no details will be ignored.
Mains voltage is not a beginner project
If it plugs into the wall, say so up front. People will tell you to stop, and they will be right.
No drive-by self promotion
Your own stuff is fine when it answers the thread. A bare link with no context is an advert.
Moderated by Matt O'Brien
Discussions
Benchmarks, fan ducts, printed cases and the eternal "do i need active cooling" question. Share temps and STLs.
Automations that work, and the ones that flooded the kitchen
Showing 15 posts.
Posts in t/raspberry_pi_lab
I deleted a comment today and I'm not sorry: mains voltage is not a beginner project
Normally I'm the bloke laughing at his own failures on here. Not today. Today someone posted (in a comment on another thread, I've removed it and messaged them, they were very good about it) a build where a cheap relay module sitting on a breadboard switched a 2400W heater on and off. Live and neutral running through breadboard jumpers. No fuse, no earth, no enclosure, screw terminals exposed on the bench. They…
- Thank you. I fix appliances for a living-ish (right to repair forever) and the number one thing I tell people is: learning to repair something does not mean you should repair the mains side of it this weekend. Unplug it, discharge it, and if there is a big capacitor in a power supply, leave it alone until someone shows you how (those can bite long after the plug is out).
- In our pump controllers the creepage between mains and logic side is designed, tested and certified, and still we get field failures from moisture and dust. On a breadboard, no chance. Good post Matt.
Printing a Pi 5 case that actually breathes (and survives a garage in July)
Hi all! This is the long version of a story that starts with a sad, droopy Pi case (my own (I'm the enclosure lady, I know)). In July my garage hit 38°C for a week. My Pi 5 lives out there running OctoPrint for the printers, in a case I printed in PLA two years ago. By the end of that week the lid had sagged in the middle like a hammock, and the Pi was throttling every afternoon. So I redesigned it properly, and…
- can u share the files bro, we have a printer at school and my pi lives in a cardboard box rn 💀
- I printed cases for two of these last month! (Leave a hole for the antenna connector, not a slot you plan to drill later (the drill wins, the case loses).)
- ESP32 da. Beginner learns GPIO, timers, interrupts, power. With Pi beginner learns apt install and thinks he learned hardware 😄
Four Pi 5s, one k3s cluster: full build log, what went wrong, and why I'd buy a mini PC next time
G'day legends. This took three weekends, two trips to Jaycar and one very long conversation with the wife about "what exactly is a control plane". Years ago Jeff Geerling's Pi Dramble videos put the idea in my head and it never left, so if you've not seen the original, start here: This is the full log. Every command I ran, everything that went wrong, and at the end an honest answer to "should you build one". Parts…
- Nice log. A little bit of a side note on the PCIe gen 3 setting: on my Pi 5 it worked fine with one NVMe and gave errors in dmesg with another one (AER messages, how it's called, "corrected error"). So if you use gen 3, check dmesg after a big copy, not only that it boots.
- "it's ONE line" in bold should be printed on every pi box. i lost an evening to a newline in cmdline.txt once. great writeup
2 years of LoRa trough sensors on a dairy farm: what I stuffed up so you don't have to
Kia ora. Not a programmer, just a dairy farmer in the Waikato who got sick of driving round on the quad every morning checking troughs. 400 cows, 28 troughs, 3 tanks. That run took me about an hour and a half before milking, every day, rain or shine. Two years ago I started teaching myself Arduino off YouTube. Now every trough and tank reports in over LoRaWAN and I get a ping on my phone if one is low. I've stuffed…
- Showing this to my Year 10s on Monday. Real-world IoT, with cows, written by someone who taught himself from YouTube. That's the whole lesson right there. Diolch Hamish!
- Float switch over ultrasonic: correct choice. Simple sensor wins in field only. In pump controllers also we keep a float switch as backup for the pressure sensor, because the float switch never lies.
I2C debugging with a ₹650 logic analyser: the 5 bugs I find every month
Every month somebody at work or on WhatsApp says "the sensor is not detecting". Nine times out of ten it is one of these five. Before you change the library or the sensor, look at the bus. The tool The cheap 24 MHz 8 channel "Saleae compatible" clone, ₹650 online. With sigrok PulseView (free) it works very well: sudo apt install pulseview sigrok-firmware-fx2lafw Sample at least 4× the bus speed, I use 8 MHz for 400…
- PCA9615 good, but cost more and need extra chip both side. For short run 1m, 100 kHz and 2.2k pull-up can. Above 1m, RS-485 like you say.
- networkchuck title energy: your home automation SUCKS. matt energy: here's a calm video and two tips. the internet needs more matts
- printf, though on the Amiga in 1989 my "printf" was changing the background colour register. You'd see a coloured band on screen showing exactly how much of the frame your routine took. Every demo coder did it. Best profiler I've ever used. Cheers, Pete
The Pi Zero that cooked itself in my letterbox (and what lives in there now)
G'day legends. This one's a confession. Last January I built a "you've got mail" notifier. Pi Zero 2 W, a reed switch on the letterbox flap, a magnet, a little Python script that pinged Home Assistant over MQTT. Took an arvo. Worked first go. Felt very clever. Then Brisbane did Brisbane. The letterbox is black powder-coated steel, faces west, and sits in full sun from about 1pm. I had the Pi logging vcgencmd…
ESP32 battery sensor: from 4 days to about a year on one 18650. Real numbers, real mistakes
My uncle has a coconut farm near Pollachi. He wanted soil moisture and temperature from 6 spots, every 10 minutes, on his phone. Easy, I said. ESP32, WiFi to the pump shed, MQTT, done. First version battery died in 4 days . This post is how it became about a year, with numbers, because "use deep sleep" is not an answer. Step 0: measure, don't guess You need two tools: A multimeter in series for the sleep current (µA…
- machane coconut farm photo please, then only I will believe Pollachi coconut is better than Kerala coconut 😂😂
- Good post. For once Arduino code without delay(1000) in loop. You could go lower with the ULP coprocessor reading the ADC without waking main CPU, but for this, no need. Correct engineering decision.
A retired banker's first Raspberry Pi: a weather station on my terrace in Chennai
Dear friends, I retired two years ago after 34 years in the IT department of a public sector bank. I began with punched cards, spent most of my career with COBOL, CICS and DB2, and learned Java in my fifties because the bank said so. My grandson, who is 17, informed me last year that COBOL is "basically dead" and that I should learn Python. I informed him that COBOL processed his grandmother's pension this morning.…
- Sir, I showed this post to my Class 11 children today. They were very surprised that a grandfather writes Python. Two of them want to build the same station for our school terrace now. Thank you for the inspiration.
- Sir, I respect everything in this post, except vi. Neovim is waiting for you 😄
Pi-hole + Unbound on an old Pi 3B: my setup after 2 year, full config
Hi all, this is my first long post here. My Pi 3B is the oldest thing in my homelab and still the most important, because when it is down the whole house have no internet and my wife know exactly who to blame :) Why Unbound and not only Pi-hole Pi-hole alone block ads, but it still forward every query to some upstream (Google, Cloudflare, or your ISP). My ISP DNS here sometimes is slow, and when I type a domain…
- Good post. One privacy nuance people should understand: recursive resolution is better than handing everything to Google, but the queries to the authoritative servers still go out unencrypted, so your ISP can still see them. Forwarding over DoT to a provider hides them from the ISP but then you trust that provider. Neither is "private". Pick your adversary.
- Same problem in Hobart, except ours are brushtails with a grudge. Conduit. Steel, not plastic. Cheers, G.
Seven dead SD cards in two years. Here is what finally fixed it
G'day legends. Went through the shed drawer on the weekend and counted seven dead microSD cards, all out of Pis that run 24/7. The weather station, the chook house door, the Pi-hole, the garage camera. Every one died the same way: fine for months, then one morning it boots read-only or doesn't boot at all. Parts I use now (AUD, roughly): second hand 120GB SATA SSD ($20 at the tip shop / marketplace), a USB 3 to SATA…
- bro this is literally why my pi wont boot 💀 found this from google. ordering an ssd adapter rn
- +1 for SSD. in my experience power cut kill more card than writes. HCMC rainy season = 3 power cut a week sometimes. a small UPS for the Pi is cheap and save a lot of headache. hope this help :)