• 7 Posts
  • 239 Comments
Joined 2 years ago
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Cake day: October 20th, 2024

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  • For a better seperarion. You examples (laptops consoles phones) all run DC, meaning they Need to turn AC to DC, needing a PCB who does it who not design it for world use? For fridges, washing machines, dryers, they run on AC, they are cheaper to make if they just don’t have a PCB and run straight on AC.

    Also note that EU kettles can run on USA network, they will just be horrible slow heaters (they are slower with about 230V/110V = ~2x)





  • This explanation is good indeed.

    Sometimes you design a circuit where the main chip runs on +3.3V reference to the chips ground at 0V, but somewhere in the proces you end up with an extension board that wants 5V below the ground. For easy of use we just call this -5V instead of renaming everything to 0, 5, and 8,3V. Renaming also has the drawback that I like to measure everything reffering to the ground of the main chip. So I personally just don’t rename and keep my reference there.

    *fixed 8.5 typo to 8.3


  • U = R x I

    volts (U, probably 19VDC) is constant. The laptop has a resistance ®. This means that the laptop has already dictated the amount of currents (I) that it pulls. You can connect an 100A charger to an phone. The phone dictates howmuch it actually pulling. There is no battery damage/harm in doing so.

    If you charge a battery at full-speed, It can heat up. This is in the long term bad for (Lithium) batteries. That’s where the myth might come from?

    *fixed formula order


  • For USB-C: Tiny little side note here, there are some cheap small-size adapters that overheat. Some adapters thotle down, but some rare ones just blink power on and off, which is bad for lithium batteries.

    Search a good brand, preferably reviewed, and GAN-type. Spend a bit more than the cheapest. Check if it has the right protocol (probably Power Delivery at some voltage) to make sure it charges at a normal speed.

    For a DC charger like OP asked. Match polarity, match Voltage. And at least match the current/watage to make sure you can charge in a reasonable amount of time





  • Nice write up!

    We went with Nuki (I wanted something european). It’s not a replacement, but rather a smart-key. Has been rock solid connectivity and locking, and it’s wired in but has a 6month battery on board. When using a wifi connection they can be controlled over MQTT with Home Assistant

    The downside is that finger print don’t work well in the rain, but it also has numbers.

    We also has a few delivery drivers get confused what button is the doorbell. But that was fixed with a bell sticker icon on the doorbel