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Posts tagged #electronics on Dynamo Geeks: 18 posts from the community, most useful first.

18 posts

Posts tagged #electronics

  1. Article

    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…

    Matt O'Brien43likes10comments

  4. Experience

    The BOR level nobody set: why our controllers reset when the farmer's motor starts

    Field returns from farms in Tiruppur district. Controllers resetting at random, and some of them came back with the settings corrupted: pressure set point became 0, or the pump type changed by itself. Bench test: perfect, 2 weeks, zero resets. "Lab bench power supply never shows this. Farm shows it on day one only." I say this sentence to every new engineer now. Going to site One farm, 200 m of cable from the…

    Karthikeyan S12likes6comments

  5. Article

    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…

    Gwen Albright10likes9comments

  7. Article

    Keyboard number 4: a split on my own PCB, and the 36 diodes I soldered backwards

    After three keyboards built from kits, I wanted to design one myself. Keyboard number 4 is a 36 key split (3 rows of 5 plus 3 thumb keys per half), on my own PCB, with an RP2040. It works now. The way it works is a little bit embarrassing, so I will tell you. The design Schematic and PCB in KiCad 8. Two identical reversible halves, so I only order one design Controller: an RP2040 board in the Pro Micro footprint,…

    Daan Visser27likes10comments

  8. Article

    ESP32 module placement: why your WiFi range is 3 meter

    Every week customers send me ESP32 board for review before production. 7 of 10 have the same problem. They say "WiFi range very bad, maybe ESP32 is bad". ESP32 is fine. Layout is bad. 1. Antenna at board edge, nothing under it The PCB antenna on the module (the zigzag part) must be at the edge of your board, or better, hanging out past the edge. Under the antenna: no copper on any layer . No ground pour, no traces,…

    Leo Chen 陈立12likes10comments

  9. Article

    Raising a daughter in Hsinchu while the news talks about blockades

    I am a process integration engineer at a foundry in Hsinchu. I will not say which one and I will not say anything about work, customers or yields, please do not ask. I want to write about something else: what it is like to live here, in the middle of a topic that people far away discuss like a strategy game. The ships on TV My daughter is 7. During the large drills, the news shows maps with red arrows around our…

    C.M. Huang 黃志明46likes15comments

  11. Article

    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…

    Karthikeyan S26likes8comments

  12. Experience

    Typhoon week at the fab: the city stops, the fab does not

    We had our first strong typhoon of the season last week. Some colleagues abroad asked me "do you get the day off?" and the answer is complicated, so I want to write about it from the inside. I cannot say anything about my company, the tools, the yields or the customers, so please do not ask. I will only write about the people. How a typhoon day works here When a typhoon is coming, each city and county government…

    C.M. Huang 黃志明30likes12comments

  13. Experience

    1981, a ZX81, 1K of RAM and the RAM pack wobble

    Back in 1981 my dad came home with a ZX81. I was 13. It had 1K of memory. Not one gigabyte, not one megabyte, one kilobyte: about the size of this paragraph. It plugged into the telly and you saved your programs to a cassette recorder, at roughly 250 bits a second, give or take, with a screech that made the dog leave the room. The keyboard was a flat membrane you pressed like a lift button. In FAST mode the screen…

    Peter Hughes6likes9comments

  15. Article

    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…

    Karthikeyan S37likes12comments

  16. Article

    Recapping an Amiga 1200 and evicting a Varta: a weekend log

    Back in 1993 I bought my A1200 from a little shop on London Road in Sheffield with money I had been told was for a new boiler. The boiler waited. The Amiga did not. Thirty-odd years later it had started doing two things that every A1200 owner learns to dread: the sound had gone thin and quiet on one channel, and when I opened it up there was a faint fishy smell. If you know, you know. This is my log of putting that…

    Peter Hughes13likes11comments

  17. Article

    This 65W charger died in 6 days. How not to buy the same one

    Quick one, because I'm still mad. 📦 Bought a 65W "GaN" USB-C charger off a marketplace listing for $22. Two ports, tiny, 4.8 stars with 3,000 reviews. Day 6, my laptop stopped charging from it. Day 7 it stopped doing anything at all and it smelled like a hot hair dryer. No fire, no drama, just dead. My own money, and the seller has stopped answering. So here's what I check now, and honestly should have checked…

    Trey Robinson30likes8comments

  18. Experience

    My first computer was a kit, a soldering iron and a very patient dad (ZX81, 1981)

    Somebody asked in the chat what everyone's first computer was, and I started typing a reply and it got out of hand, so here it is as a proper post. Put the kettle on. Back in 1981 I was thirteen, and my dad worked shifts at a steelworks in Rotherham. He was not a computer man at all, but he had seen an advert for the Sinclair ZX81 in the paper and worked out, on the back of an envelope, that the kit version was…

    Peter Hughes13likes10comments

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