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Cake day: July 2nd, 2023

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  • 470uf should be fine - bigger is almost always better, except if you sacrifice higher ESR for it in an application that requires lower ESR. It’s pretty common to combine a large cap with higher ESR (like an Electrolytic or tantalum) with low ESR ceramic caps. That way the large cap can handle the high speed bulk C while the smaller cap can handle the high speed stuff and switching edges.

    Did you make sure the cap you picked out was rated for the voltage you are working with? For hobbyist stuff it’s usually a good idea to heavily derate voltages, to avoid blowing things up. For example, if I was working with a 24V power supply, I wouldn’t nab a 25V cap; I would spring for a 35V (or even a 50V if I’m feeling particularly paranoid). You’ll see derating like this commonly in commercial applications, and extremely frequently in military/aerospace applications.

    As a rule of thumb you should always derate by at least 20%, then increase to 100% depending on how much ripple or switching the cap will see. For this application I’d probably want to derate to at least 50%


  • Caps are definitely the first thing to try. To add on, the higher your frequency, the smaller caps you’ll need. At 10kHz you’ll need around 200uF of decoupling but at 50kHz you’d only need around 40uF. The smaller capacitance means you can find caps with better ESR, or just fit into a smaller space in general.

    The drawback of higher frequency is that you’ll be charging and discharging the gate of the MOSFET more often, which could mean heating it up and hitting thermal limits quicker. There’s also a tradeoff within the MOSFET itself between low on-resistance and lower required gate charge - for slow switching you can find a FET with low Rds and high gate charge since youd be switching less often, but for very high frequency applications the amount of energy you put into charging and discharging the FET (mostly since the FET will spend a longer time in its linear region) can outweigh the savings of the lower resistance. Yay tradeoffs!



  • draz@lemmy.worldtoADHD@lemmy.worldWhats your current hyperfocus?
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    1 year ago

    You’d be surprised! I have a few smaller Lego sets (and I have tons of spare from childhood), and the quality of some knockoffs is basically identical to the real deal. Trust me when I say the knockoffs have figured it out in 2023. The real differentiator comes in packaging and quality control. It’s not uncommon for a set to have a few missing or incorrect bricks, which you need to order or replace from your own collection. In the end ABS is ABS and this molding tech is literally 50+ years old; there’s nothing holy about Legos process.

    If you do a quick search you’ll also find tons of people complaining about sore thumbs and fingers, particularly after putting together large sets. There’s plenty to flame the knockoffs about, but this ain’t it


  • For the past two weeks it’s been Legos. I always wanted to build big kits as a kid, but they’re way way too expensive, even for me today now that I’m making decent money. Well lo and behold, there are tons of knockoff Lego manufacturers, many of whom will just sell you 100% ripped off sets for dirt cheap. I just put the final piece on the new Rivendell set today, and I’m going to start the millennium falcon UCS here soon. Unfortunately, it’ll have to wait until my thumbs heal up from all the damage - placing tons of bricks really chews up the tips of your thumbs and index fingers